Iron-nickel magnetic powder core and method for manufacturing the same

Abstract

This invention provides a composite iron-nickel magnetic powder and its preparation method. The preparation method includes the following steps: (1) mixing a phosphorus source solution with iron-nickel magnetic powder, adding magnesium trisilicate, heating and stirring, and then annealing in one step to obtain a sintered material; (2) mixing the sintered material obtained in step (1) with a passivating agent solution, heating and stirring to obtain a passivated magnetic powder, mixing the passivated magnetic powder with a solvent, adjusting the pH, adding tetraethyl orthosilicate to react, and obtaining an insulating coating powder; (3) mixing the insulating coating powder obtained in step (2) with a binder solution, drying, adding a release powder and stirring, pressing, and then annealing in two steps to obtain the iron-nickel magnetic powder core. This invention uses a method of multiple coatings and chemical generation of silicon-containing coatings to uniformly coat the surface of soft magnetic powder, resulting in good insulation and effectively improving the various soft magnetic properties of the magnetic core.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology and relates to an iron-nickel magnetic powder core and its preparation method. Background Technology

[0002] As electronic products are upgraded, the requirements for the practicality, safety and reliability of inductor components are constantly increasing, and the demand for small-size, high-power inductors is also increasing.

[0003] Metal magnetic powder is a key functional material for inductor components. Soft metal magnetic powder cores are a new type of soft magnetic functional material obtained by coating an insulating material onto the surface of alloy powder, followed by pressing, molding, and heat treatment annealing. During the preparation of the magnetic powder core, the magnetic powder particles are first insulated. Interparticle insulation significantly improves the resistivity of the magnetic powder core, thereby reducing high-frequency losses and heat generation. Furthermore, the magnetic powder also requires chemical methods to coat the surface of the metal magnetic powder particles with an insulating layer to further increase resistivity and reduce high-frequency losses.

[0004] CN109754972A discloses a soft magnetic powder for high-frequency molded inductors and its preparation method. The method involves mixing different particle sizes and types of soft magnetic metal powders, such as iron-silicon-chromium alloy powder, carbonyl iron powder, iron-silicon-aluminum alloy powder, iron-nickel alloy powder, and iron-silicon alloy powder, in a specific ratio. The mixture undergoes acid passivation, followed by insulation with a mixture of silica powder, magnesium silicate, and talc powder. Resin is then used for bonding, and finally, lubricating powder is added to obtain the soft magnetic powder. This invention produces soft magnetic inductors with high resistivity and can be used at high frequencies, but the overall effective permeability is relatively low, and the finer powder particle size results in higher costs.

[0005] CN114082942A discloses a method for preparing a metal magnetic powder core. The method involves passivating the metal magnetic powder with a weak acid and then sequentially adding it to organic and inorganic coating solutions. By adjusting the pH of the organic coating solution, dopamine hydrochloride polymerizes, forming polydopamine particles on the surface of the magnetic powder particles, which then extend to form an organic thin film. Subsequently, by adjusting the pH of the inorganic coating solution, tetraethyl orthosilicate undergoes hydrolysis and condensation, forming a SiO2 thin film on the surface of the magnetic powder particles. This results in a polydopamine and SiO2 composite thin film formed from the inside out on the surface of the magnetic powder particles. This preparation method can improve the resistivity of the magnetic powder core and effectively reduce AC losses, while also significantly improving the mechanical strength of the magnetic powder core. However, the overall applicable pressing density and effective magnetic permeability are relatively low, and the entire process is complex.

[0006] Current technologies mainly involve coating silicon-containing compounds onto the surface of magnetic powder particles. Methods include inorganic coating, organic coating, and inorganic-organic coating, aiming to reduce high-frequency eddy current losses. However, all of these methods suffer from problems such as poor coating effect, low consistency, and difficulty in process control. Summary of the Invention

[0007] The purpose of this invention is to provide an iron-nickel magnetic powder core and its preparation method. This invention uses a method of multiple coating and chemical generation of silicon-containing coatings to uniformly coat the surface of soft magnetic powder. The process is easy to control, has good insulation effect, can effectively improve the various soft magnetic properties of the magnetic core, and the process is controllable, which can meet the future needs of the electronics and electrical appliance fields.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing an iron-nickel magnetic powder core, the method comprising the following steps:

[0010] (1) The phosphorus source solution was mixed with iron-nickel magnetic powder, magnesium trisilicate was added, and the mixture was heated and stirred. After one-step annealing, a sintered material was obtained.

[0011] (2) The calcined material obtained in step (1) is mixed with the passivating agent solution, heated and stirred to obtain passivated magnetic powder, the passivated magnetic powder is mixed with solvent and the pH is adjusted, and tetraethyl orthosilicate is added to react to obtain insulating coating powder.

[0012] (3) The insulating coating powder obtained in step (2) is mixed and stirred with the binder solution, dried, and then the release powder is added and stirred. After pressing, a two-step annealing process is performed to obtain the iron-nickel magnetic powder core.

[0013] This invention employs a method of multiple coatings and chemically generating silicon-containing coatings to uniformly coat the surface of soft magnetic powder. The process is easy to control and has good insulation effect. Through secondary annealing and multiple coating processes, the resulting magnetic powder core possesses excellent soft magnetic properties such as high permeability, low loss, and high DC superposition.

[0014] Preferably, the phosphorus source in step (1) includes phosphoric acid.

[0015] Preferably, the mass ratio of the phosphorus source to the iron-nickel magnetic powder is (0.1-5):100, for example: 0.1:100, 0.5:100, 1:100, 2:100 or 5:100, etc.

[0016] Preferably, the solvent of the phosphorus source solution includes anhydrous ethanol.

[0017] Preferably, the mass ratio of magnesium trisilicate to iron-nickel magnetic powder is (0.1-5):100, for example: 0.1:100, 0.5:100, 1:100, 2:100 or 5:100, etc., and preferably (1-3):100.

[0018] In the preparation method described in this invention, under acidic conditions, magnesium trisilicate reacts with phosphate to generate magnesium phosphate and colloidal SiO2, forming a relatively complete insulating coating layer on the powder surface.

[0019] Preferably, the temperature of the heating and stirring in step (1) is 35 to 50°C, for example: 35°C, 38°C, 40°C, 45°C or 50°C.

[0020] Preferably, the heating and stirring time is 0.5 to 2 hours, for example: 0.5 hours, 0.8 hours, 1 hour, 1.5 hours or 2 hours.

[0021] Preferably, the process involves heating and stirring followed by drying.

[0022] Preferably, the drying temperature is 110-130°C, for example: 110°C, 115°C, 120°C, 125°C or 130°C.

[0023] Preferably, the atmosphere for the one-step annealing process in step (1) includes a nitrogen atmosphere.

[0024] Preferably, the temperature of the one-step annealing process is 600 to 1000°C, for example: 600°C, 700°C, 800°C, 900°C, or 1000°C.

[0025] Preferably, the annealing process takes 1 to 5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours.

[0026] Preferably, the passivating agent in step (2) includes phosphoric acid.

[0027] Preferably, the mass ratio of phosphoric acid to iron-nickel magnetic powder is (0.1-5):100, for example: 0.1:100, 0.5:100, 1:100, 2:100 or 5:100, etc.

[0028] Preferably, the solvent of the passivating agent solution includes any one or a combination of at least two of methanol, ethanol, butanol or acetone.

[0029] Preferably, the temperature of the heating and stirring in step (2) is 35 to 50°C, for example: 35°C, 38°C, 40°C, 45°C or 50°C.

[0030] Preferably, the heating and stirring time is 0.5 to 2 hours, for example: 0.5 hours, 0.8 hours, 1 hour, 1.5 hours or 2 hours.

[0031] Preferably, the process involves heating and stirring followed by drying.

[0032] Preferably, the drying temperature is 110-130°C, for example: 110°C, 115°C, 120°C, 125°C or 130°C.

[0033] Preferably, the solvent in step (2) includes anhydrous ethanol and / or deionized water, and more preferably anhydrous ethanol and deionized water.

[0034] Preferably, the pH adjuster includes ammonia.

[0035] Preferably, the pH is 7.5 to 9.5, for example: 7.5, 8, 8.5, 9 or 9.5, etc.

[0036] Preferably, the mass ratio of the tetraethyl orthosilicate to the passivating magnetic powder is (1-10):100, for example: 1:100, 2:100, 5:100, 8:100 or 10:100, etc., and preferably (1-5):100.

[0037] Under alkaline conditions, tetraethyl orthosilicate undergoes hydrolysis and condensation, forming a new SiO2 film on the surface of the magnetic powder.

[0038] Preferably, the reaction time is 0.5 to 2 hours, for example: 0.5 hours, 0.8 hours, 1 hour, 1.5 hours or 2 hours.

[0039] Preferably, the adhesive in step (3) comprises any one or a combination of at least two of epoxy resin, silicone resin or phenolic resin.

[0040] Preferably, the mass ratio of the adhesive to the insulating coating powder is (0.5-3):100, for example: 0.5:100, 1:100, 2:100 or 3:100, etc.

[0041] Preferably, the solvent of the adhesive solution includes acetone.

[0042] Preferably, the mixing time is 20 to 40 minutes, for example: 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes.

[0043] Preferably, the drying temperature in step (3) is 110 to 130°C, for example: 110°C, 115°C, 120°C, 125°C or 130°C.

[0044] Preferably, the stripping powder comprises any one or a combination of at least two of zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, or graphite powder.

[0045] Preferably, the pressure of the pressing process in step (3) is 1400-2000 MPa, for example: 1400 MPa, 1500 MPa, 1600 MPa, 1800 MPa or 2000 MPa, etc.

[0046] Preferably, the temperature of the two-step annealing process is 600-800℃, for example: 600℃, 650℃, 700℃, 750℃ or 800℃.

[0047] Preferably, the two-step annealing process takes 30 to 90 minutes, for example: 30 minutes, 40 minutes, 50 minutes, 60 minutes, or 90 minutes.

[0048] In a second aspect, the present invention provides an iron-nickel magnetic powder core, which is prepared by the method described in the first aspect.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The present invention uses a method of multiple coating and chemical generation of silicon-containing coatings to uniformly coat the surface of soft magnetic powder. The process is easy to control, has good insulation effect, can effectively improve the various soft magnetic properties of the magnetic core, and the process is controllable, which can meet the future needs of the electronics and electrical appliance fields.

[0051] (2) In an acidic environment, this invention generates a phosphate and SiO2 coating layer through the reaction of magnesium trisilicate and phosphoric acid. This effectively improves the insulation between powder particles and the overall bonding strength and toughness between film layers, thereby enhancing the reliability of the insulating layer while releasing internal stress during high-temperature annealing of the magnetic powder. A relatively complete and uniform SiO2 thin film layer is obtained through the hydrolysis and condensation of tetraethyl orthosilicate in an ammonia environment. This minimizes the adverse effects of multiple insulating layers weakening the magnetic properties of the magnetic powder, ensuring sufficient insulation, improving the overall mechanical strength of the final product, and effectively releasing internal stress caused by pressing during high-temperature annealing. Detailed Implementation

[0052] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0053] Example 1

[0054] This embodiment provides an iron-nickel magnetic powder core, and the preparation method of the iron-nickel magnetic powder core is as follows:

[0055] (1) Select iron-nickel magnetic powder with a particle size of about 200 mesh. The alloy composition by mass percentage is Ni 49.02%, Fe 50.95%, Al 0.01%, and Si 0.02%. Using the mass of iron-nickel magnetic powder as the ratio basis, first add 2% phosphoric acid, 10% anhydrous ethanol and magnetic powder and mix and stir to form a uniform slurry. Then add 1.5% magnesium trisilicate and mix. Stir at 40°C for 1 hour. Then raise the temperature to 120°C to completely evaporate the solvent and obtain dry iron-nickel magnetic powder. Then anneal the magnetic powder at 800°C for 2 hours in a nitrogen atmosphere to obtain a sintered material.

[0056] (2) Using the mass of iron-nickel magnetic powder in step (1) as the ratio basis, first add 0.2% phosphoric acid to 10% acetone solvent to form a passivating agent, then add magnetic powder and mix and stir at 40°C for 30 minutes, then raise the temperature to 120°C to evaporate the solvent and obtain dry passivation powder. Using the mass of passivation powder as the ratio basis, first add 15% anhydrous ethanol, 1% deionized water and passivation magnetic powder and mix and stir to form a uniform slurry, then add ammonia water to adjust pH=8, and finally add 2% tetraethyl orthosilicate and stir for 1 hour, then raise the temperature to 120°C to evaporate the solvent and obtain dry insulating coating powder.

[0057] (3) Using the mass of insulating powder as a proportional basis, 1% silicone resin is first added to 10% acetone solvent to form a binder solution, then insulating magnetic powder is added, and stirred for 30 minutes to obtain a uniform solution. Then, the temperature is raised to 120°C to evaporate the solution and obtain a dry binder coating powder. Using the mass of the binder coating powder as a proportional basis, 0.5% zinc stearate and magnetic powder are mixed and stirred for 30 minutes to obtain a soft magnetic metal powder that can be used to press a magnetic powder core. The soft magnetic metal powder is pressed into shape under a pressure of 1600 MPa. The pressed magnetic powder core is placed in a nitrogen atmosphere at 700°C for 60 minutes for heat treatment to obtain the iron-nickel magnetic powder core.

[0058] Example 2

[0059] This embodiment provides an iron-nickel magnetic powder core, and the preparation method of the iron-nickel magnetic powder core is as follows:

[0060] (1) Select iron-nickel magnetic powder with a particle size of about 200 mesh. The alloy composition by mass percentage is Ni 49.02%, Fe 50.95%, Al 0.01%, and Si 0.02%. Using the mass of iron-nickel magnetic powder as the ratio basis, first add 1% phosphoric acid, 10% anhydrous ethanol and magnetic powder and mix and stir to form a uniform slurry. Then add 3% magnesium trisilicate and mix. Stir at 40°C for 1 hour. Then raise the temperature to 120°C to completely evaporate the solvent and obtain dry iron-nickel magnetic powder. Then anneal the magnetic powder at 900°C for 2 hours in a nitrogen atmosphere to obtain a sintered material.

[0061] (2) Using the mass of iron-nickel magnetic powder in step (1) as the ratio basis, first add 0.1% phosphoric acid to 10% acetone solvent to form a passivating agent, then add magnetic powder and mix and stir at 40℃ for 30 min, then raise the temperature to 120℃ to evaporate the solvent and obtain dry passivation powder. Using the mass of passivation powder as the ratio basis, first add 25% anhydrous ethanol, 3% deionized water and passivation magnetic powder and mix and stir to form a uniform slurry, then add ammonia water to adjust pH=8.5, and finally add 4% tetraethyl orthosilicate, stir for 1 h, then raise the temperature to 120℃ to evaporate the solvent and obtain dry insulating coating powder.

[0062] (3) Using the mass of insulating powder as a proportional basis, 2% phenolic resin is first added to 10% acetone solvent to form a binder solution, then insulating magnetic powder is added, and stirred for 30 minutes to obtain a uniform solution. Then, the temperature is raised to 120°C to evaporate the solution and obtain a dry binder coating powder. Using the mass of the binder coating powder as a proportional basis, 0.2% zinc stearate and magnetic powder are mixed and stirred for 30 minutes to obtain a soft magnetic metal powder that can be used to press a magnetic powder core. The soft magnetic metal powder is pressed into shape under a pressure of 1800 MPa. The pressed magnetic powder core is placed in a nitrogen atmosphere at 600°C for 90 minutes for heat treatment to obtain the iron-nickel magnetic powder core.

[0063] Example 3

[0064] This embodiment provides an iron-nickel magnetic powder core, and the preparation method of the iron-nickel magnetic powder core is as follows:

[0065] (1) Select iron-nickel magnetic powder with a particle size of about 200 mesh. The alloy composition by mass percentage is Ni 49.02%, Fe 50.95%, Al 0.01%, and Si 0.02%. Using the mass of iron-nickel magnetic powder as the ratio basis, first add 4% phosphoric acid, 10% anhydrous ethanol and magnetic powder and mix and stir to form a uniform slurry. Then add 1% magnesium trisilicate and mix. Stir at 40°C for 1 hour. Then raise the temperature to 120°C to completely evaporate the solvent and obtain dry iron-nickel magnetic powder. Then anneal the magnetic powder at 800°C for 2 hours in a nitrogen atmosphere to obtain a sintered material.

[0066] (2) Using the mass of iron-nickel magnetic powder in step (1) as the ratio basis, first add 0.3% phosphoric acid to 10% methanol solvent to form a passivating agent, then add magnetic powder and mix and stir at 40℃ for 30 min, then raise the temperature to 120℃ to evaporate the solvent to obtain dry passivation powder. Using the mass of passivation powder as the ratio basis, first add 10% anhydrous ethanol, 2% deionized water and passivation magnetic powder and mix and stir to form a uniform slurry, then add ammonia water to adjust pH=8, and finally add 1% tetraethyl orthosilicate and stir for 1 h, then raise the temperature to 120℃ to evaporate the solvent to obtain dry insulating coating powder.

[0067] (3) Using the mass of insulating powder as a proportional basis, 0.8% epoxy resin is first added to 10% acetone solvent to form a binder solution, then insulating magnetic powder is added, and stirred for 30 minutes to obtain a uniform solution. Then, the temperature is raised to 120°C to evaporate the solution and obtain a dry binder coating powder. Using the mass of the binder coating powder as a proportional basis, 1% zinc stearate and magnetic powder are mixed and stirred for 30 minutes to obtain a soft magnetic metal powder that can be used to press a magnetic powder core. The soft magnetic metal powder is pressed into shape under a pressure of 1400 MPa. The pressed magnetic powder core is placed in an argon atmosphere at 800°C for 60 minutes for heat treatment to obtain the iron-nickel magnetic powder core.

[0068] Example 4

[0069] The only difference between this embodiment and Embodiment 1 is that the amount of magnesium trisilicate added is 0.5% of the mass of the iron-nickel magnetic powder; all other conditions and parameters are exactly the same as in Embodiment 1.

[0070] Example 5

[0071] The only difference between this embodiment and Embodiment 1 is that the amount of magnesium trisilicate added is 5% of the mass of the iron-nickel magnetic powder; all other conditions and parameters are exactly the same as in Embodiment 1.

[0072] Example 6

[0073] The only difference between this embodiment and Embodiment 1 is that the amount of tetraethyl orthosilicate added is 0.5% of the mass of the passivating magnetic powder; all other conditions and parameters are exactly the same as in Embodiment 1.

[0074] Example 7

[0075] The only difference between this embodiment and Embodiment 1 is that the amount of tetraethyl orthosilicate added is 8% of the mass of the passivating magnetic powder; all other conditions and parameters are exactly the same as in Embodiment 1.

[0076] Comparative Example 1

[0077] This comparative example provides an iron-nickel magnetic powder core, and the preparation method of the iron-nickel magnetic powder core is as follows:

[0078] (1) Select iron-nickel magnetic powder with a particle size of about 200 mesh. The alloy composition by mass percentage is Ni 49.02%, Fe 50.95%, Al 0.01%, and Si 0.02%. Using the mass of iron-nickel magnetic powder as the ratio basis, add 15% anhydrous ethanol, 1% deionized water and passivation magnetic powder and mix and stir to form a uniform slurry. Then add ammonia water to adjust the pH to 8. Finally, add 2% tetraethyl orthosilicate and stir for 1 hour. Then heat to 120°C to evaporate the solvent and obtain dry insulating coating powder. Then place the magnetic powder in a nitrogen atmosphere and anneal at 800°C for 2 hours to obtain a sintered material.

[0079] (2) Using the mass of iron-nickel magnetic powder in step (1) as the ratio basis, first add 0.2% phosphoric acid to 10% acetone solvent to form a passivating agent, then add magnetic powder and mix and stir at 40°C for 30 minutes, then raise the temperature to 120°C to evaporate the solvent and obtain dry passivation powder. Using the mass of passivation powder as the ratio basis, add 2% phosphoric acid, 10% anhydrous ethanol and magnetic powder and mix and stir to form a uniform slurry. Then add 1.5% magnesium trisilicate, mix and stir at 40°C for 1 hour, then raise the temperature to 120°C to completely evaporate the solvent and obtain insulating coating powder.

[0080] (3) Based on the mass of the insulating powder, 1% silicone resin was first added to 10% acetone solvent to form a binder solution, and then the insulating magnetic powder was added. The mixture was stirred for 30 minutes to obtain a uniform solution. The solution was then heated to 120°C to evaporate and obtain a dry binder coating powder. Based on the mass of the binder coating powder, 0.5% zinc stearate and magnetic powder were mixed and stirred for 30 minutes to obtain a soft magnetic metal powder that can be used to press a magnetic powder core. The soft magnetic metal powder was pressed into shape under a pressure of 1500 MPa. The pressed magnetic powder core was then heat-treated in a nitrogen atmosphere at 700°C for 60 minutes to obtain the iron-nickel magnetic powder core.

[0081] Comparative Example 2

[0082] The only difference between this comparative example and Example 1 is that no coating is performed before the first annealing step (1), while the other conditions and parameters are exactly the same as in Example 1.

[0083] Comparative Example 3

[0084] The only difference between this comparative example and Example 1 is that the coating process in step (2) is not performed, and the two-step annealing is performed directly. The other conditions and parameters are exactly the same as those in Example 1.

[0085] Performance testing:

[0086] Iron-nickel magnetic powder cores prepared in Examples 1-7 and Comparative Examples 1-3 were tested. The permeability and DC superposition performance at 100 Oe were measured under test conditions of 100 kHz and 1 V. The loss of the magnetic powder cores was measured under test conditions of 1 MHz, 50 mT, and 25 °C. The test results are shown in Table 1.

[0087] Table 1

[0088]

[0089]

[0090] As can be seen from Table 1, the iron-nickel magnetic powder cores prepared by the method of the present invention have high permeability, good DC superposition performance, and low loss, as can be obtained from Examples 1-3.

[0091] A comparison of Examples 1 and 4-5 shows that the amount of magnesium trisilicate added during the preparation of the iron-nickel magnetic powder core of the present invention affects the performance of the obtained iron-nickel magnetic powder core. Controlling the amount of magnesium trisilicate added to 1-3% of the mass of the iron-nickel magnetic powder results in better performance of the obtained iron-nickel magnetic powder core. If the amount of magnesium trisilicate added is too large, it will lead to a decrease in magnetic permeability, an increase in coercivity, and an increase in hysteresis loss. If the amount of magnesium trisilicate added is too small, it will lead to an incomplete coating layer, too low magnetic powder core resistance, and too high overall loss.

[0092] A comparison of Examples 1 and 6-7 shows that the amount of tetraethyl orthosilicate added during the preparation of the iron-nickel magnetic powder core of the present invention affects the performance of the obtained iron-nickel magnetic powder core. Controlling the amount of tetraethyl orthosilicate added to 1-5% of the mass of the iron-nickel magnetic powder results in a better performance of the obtained iron-nickel magnetic powder core. If the amount of tetraethyl orthosilicate added is too large, it will lead to excessive loss of the magnetic powder core. If the amount of tetraethyl orthosilicate added is too small, it will lead to excessively low density and effective permeability of the magnetic powder core.

[0093] Comparing Example 1 and Comparative Example 1, it can be seen that in the preparation process of the iron-nickel magnetic powder core of the present invention, the magnesium trisilicate reaction is carried out first. In an acidic environment, magnesium trisilicate reacts with phosphate to generate magnesium phosphate and colloidal SiO2, which forms a relatively complete insulating coating layer on the powder surface. The subsequent coating layer of silicon dioxide formed by the hydrolysis of tetraethyl orthosilicate is relatively thin, mainly to improve the coating consistency and uniformity. The order of the two is quite important.

[0094] As can be seen from the comparison between Example 1 and Comparative Examples 2-3, the present invention uses a method of multiple coatings and chemical generation of silicon-containing coatings to uniformly coat the surface of soft magnetic powder. The process is easy to control, the insulation effect is good, and the resulting coating layer is uniform, stable and complete, which effectively improves the performance of the magnetic powder core.

[0095] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing an iron-nickel magnetic powder core, characterized in that, The preparation method includes the following steps: (1) The phosphorus source solution is mixed with iron-nickel magnetic powder, magnesium trisilicate is added, and the mixture is heated and stirred. After one-step annealing, a sintered material is obtained. (2) The calcined material obtained in step (1) is mixed with the passivating agent solution, heated and stirred to obtain passivated magnetic powder. The passivated magnetic powder is mixed with a solvent and the pH is adjusted. Tetraethyl orthosilicate is added to react and an insulating coating powder is obtained. (3) The insulating coating powder obtained in step (2) is mixed and stirred with the binder solution, dried, and then the release powder is added and stirred. After pressing, a two-step annealing process is performed to obtain the iron-nickel magnetic powder core. The mass ratio of magnesium trisilicate to iron-nickel magnetic powder is (1~3):100; The mass ratio of the tetraethyl orthosilicate to the passivating magnetic powder is (1~5):100; The phosphorus source in step (1) includes phosphoric acid, and the temperature of heating and stirring in step (1) is 35~50℃; In an acidic environment, magnesium trisilicate and phosphoric acid react to generate phosphate and a SiO2 coating layer.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the phosphorus source to the iron-nickel magnetic powder is (0.1~5):

100.

3. The preparation method according to claim 1, characterized in that, The solvent for the phosphorus source solution includes anhydrous ethanol.

4. The preparation method according to claim 1, characterized in that, The heating and stirring time in step (1) is 0.5~2h.

5. The preparation method according to claim 1, characterized in that, After heating and stirring in step (1), the product is dried.

6. The preparation method according to claim 5, characterized in that, The drying process is carried out at a temperature of 110~130℃.

7. The preparation method according to claim 1, characterized in that, The atmosphere for the annealing process includes a nitrogen atmosphere.

8. The preparation method according to claim 1, characterized in that, The temperature for the first-step annealing process is 600~1000℃.

9. The preparation method according to claim 1, characterized in that, The annealing process takes 1 to 5 hours.

10. The preparation method according to claim 1, characterized in that, The passivating agent in step (2) includes phosphoric acid.

11. The preparation method according to claim 10, characterized in that, The mass ratio of phosphoric acid to iron-nickel magnetic powder is (0.1~5):

100.

12. The preparation method according to claim 1, characterized in that, The solvent of the passivating agent solution includes any one or a combination of at least two of methanol, ethanol, butanol or acetone.

13. The preparation method according to claim 1, characterized in that, The temperature for heating and stirring in step (2) is 35~50℃.

14. The preparation method according to claim 1, characterized in that, The heating and stirring time in step (2) is 0.5~2h.

15. The preparation method according to claim 1, characterized in that, After heating and stirring in step (2), the product is dried.

16. The preparation method according to claim 15, characterized in that, The drying process is carried out at a temperature of 110~130℃.

17. The preparation method according to claim 1, characterized in that, The solvent in step (2) includes anhydrous ethanol and / or deionized water.

18. The preparation method according to claim 1, characterized in that, The solvents used in step (2) are anhydrous ethanol and deionized water.

19. The preparation method according to claim 1, characterized in that, The pH adjuster includes ammonia.

20. The preparation method according to claim 1, characterized in that, The pH value is 7.5 to 9.

5.

21. The preparation method according to claim 1, characterized in that, The reaction time is 0.5 to 2 hours.

22. The preparation method according to claim 1, characterized in that, The adhesive in step (3) includes any one or a combination of at least two of epoxy resin, silicone resin or phenolic resin.

23. The preparation method according to claim 1, characterized in that, The mass ratio of the adhesive to the insulating coating powder is (0.5~3):

100.

24. The preparation method according to claim 1, characterized in that, The solvent for the adhesive solution includes acetone.

25. The preparation method according to claim 1, characterized in that, The mixing and stirring time is 20-40 minutes.

26. The preparation method according to claim 1, characterized in that, The drying temperature in step (3) is 110~130℃.

27. The preparation method according to claim 1, characterized in that, The stripping powder includes any one or a combination of at least two of zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, or graphite powder.

28. The preparation method according to claim 1, characterized in that, The pressure of the pressing process in step (3) is 1400~2000MPa.

29. The preparation method according to claim 1, characterized in that, The temperature for the two-step annealing process is 600~800℃.

30. The preparation method according to claim 1, characterized in that, The two-step annealing process takes 30 to 90 minutes.

31. A type of iron-nickel magnetic powder core, characterized in that, The iron-nickel magnetic powder core is prepared by the method described in any one of claims 1-30.

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