Low-chromium anti-rust iron-silicon-chromium magnetic powder core and preparation method thereof

Abstract

The application discloses a low-chromium rust-proof iron-silicon-chromium magnetic powder core and a preparation method thereof, and relates to the technical field of soft magnetic materials. The preparation method comprises the following steps: firstly, performing passivation treatment on iron-silicon-chromium alloy powder by using a diluent and a passivation agent; secondly, coating the iron-silicon-chromium alloy powder by using low-melting-point organic silicon resin and a coupling agent in sequence; and thirdly, obtaining the low-chromium rust-proof iron-silicon-chromium magnetic powder core by performing granulation, die molding and heat treatment. The iron-silicon-chromium alloy prepared by using the water-vapor combined atomization method contains a small amount of Mn elements while reducing the content of Cr, and the magnetic core density and permeability are improved under the condition that the direct-current superposition characteristics remain unchanged. After the passivation treatment is performed on the iron-silicon-chromium alloy, the low-chromium iron-silicon-chromium magnetic powder core is prepared by using the fluidized coating process and coupling coating, and the low-chromium iron-silicon-chromium magnetic powder core can achieve the same rust-proof effect as high-chromium, and can meet the development requirements of one-piece integrated inductance miniaturization, high permeability and high power.

Description

Technical Field

[0001] This invention relates to the field of soft magnetic materials technology, and in particular to a low-chromium, rust-resistant iron-silicon-chromium magnetic powder core and its preparation method. Background Technology

[0002] With the development of electronic information technology, electronic components are becoming increasingly miniaturized, mobile, and multifunctional. This necessitates that the magnetic cores of high-performance energy storage devices possess high saturation magnetic induction density, low loss, and good performance stability. Currently, metal powder cores mainly include iron powder cores, molybdenum permalloy powder cores, high flux powder cores, iron-silicon powder cores, and iron-silicon-chromium powder cores. Among these, iron-silicon-chromium powder cores possess high saturation magnetic induction intensity, excellent DC superposition characteristics, and high resistivity. These characteristics give iron-silicon-chromium alloy magnetic powder unparalleled advantages over other soft magnetic materials in many applications.

[0003] Although iron-silicon-chromium alloy magnetic powder has relatively high resistivity, its application performance can be improved through appropriate heat treatment and surface insulation treatment to further enhance its DC superposition characteristics and reduce losses. Chinese patent CN202210127929.5 discloses an insulating coating method for soft magnetic powder, which involves three coating processes on iron-silicon-chromium alloy powder to obtain powder with high insulation, but the insulation level is only 1G, which is relatively low. Furthermore, using banana oil as a solvent results in a longer evaporation time and higher toxicity compared to acetone, thus increasing production costs. In addition, iron-silicon-chromium magnetic powder cores are mainly composed of Si, Cr, and Fe. The addition of Si increases the resistivity of the material, making it suitable for higher frequencies, while Cr increases the environmental reliability of the inductor and improves its rust resistance, eliminating the need for spray coating and better complying with RoHS requirements. However, chromium, as a major raw material, generates chromium slag during production. Due to weathering, it easily forms insoluble trivalent chromium or readily soluble hexavalent chromium, which migrates into surface water or groundwater. According to the "Soil Environmental Quality Standard," the chromium content in farmland soil should be controlled below 350 PPM. Excessive chromium in the soil inhibits the nitrification of organic matter. Both trivalent and hexavalent chromium are harmful to human health, easily absorbed, and can accumulate in the body. Hexavalent chromium is 100 times more toxic than trivalent chromium, a strong mutagen that can induce lung and nasopharyngeal carcinoma, while trivalent chromium has teratogenic effects. Furthermore, if the chromium content in the iron-silicon-chromium magnetic powder core reaches 6–9 wt%, the material cost will increase accordingly. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a low-chromium rust-proof iron-silicon-chromium magnetic powder core and its preparation method.

[0005] The present invention proposes a method for preparing a low-chromium, rust-resistant iron-silicon-chromium magnetic powder core, comprising the following steps:

[0006] S1. Raw material selection: The iron-silicon-chromium alloy powder obtained by water-vapor combined atomization powdering has the following composition by mass percentage: Si 3.0~9.0wt%, Cr 1.5~4.5wt%, Mn 0.2-0.5wt%, with the balance being Fe;

[0007] S2. Powder passivation: After mixing the diluent and passivating agent, add the iron-silicon-chromium alloy powder, stir and mix, dry under a protective atmosphere, and sieve to obtain passivating powder.

[0008] S3. Vaporization Coating: A fluidized bed heating coating process is adopted, using low melting point organosilicon resin as a vaporization coating agent for coating, followed by cooling and sieving to obtain vaporization coated powder.

[0009] S4. Coupling coating: Mix the diluent and coupling agent, add vaporization coating powder, stir and mix, dry, and sieve to obtain coupling coating powder;

[0010] S5. Granulation: Mix the diluent and binder, add the coupling coating powder, stir and mix, dry, and sieve to obtain granulated powder;

[0011] S6. Compression molding: Add zinc stearate to the granulated powder, compress and mold, and clean the edges and burrs to obtain the blank;

[0012] S7. Heat treatment: The blank is annealed in air atmosphere to obtain the final product.

[0013] Preferably, the diluent is one of anhydrous ethanol, ethyl acetate, and acetone;

[0014] The passivating agent is one or more of nitric acid ethanol solution, chromic acid, and phosphoric acid;

[0015] The vaporization coating agent is one or more of dimethyl silicone oil, amino silicone oil, and ethyl silicate.

[0016] The coupling agent is one of silane coupling agents, aluminate coupling agents, and titanate coupling agents;

[0017] The adhesive is one or more of phenolic resin, epoxy resin, polyvinyl alcohol, and polyvinyl butyral.

[0018] Preferably, in S1, the iron-silicon-chromium alloy powder passes through a 300-500 mesh sieve.

[0019] Preferably, in step S2, the amount of diluent used is 10-20 wt% of the mass of the iron-silicon-chromium alloy powder;

[0020] The amount of passivating agent used is 0.1 to 0.5 wt% of the iron-silicon-chromium alloy powder.

[0021] The drying temperature is 100-150℃ and the time is 60-120 minutes; after drying, it is passed through a 300-500 mesh sieve.

[0022] Preferably, in step S3, the amount of the low-melting-point silicone resin is 0.1% to 1.0% of the mass of the passivation powder;

[0023] In the fluidized bed heating and coating process, the temperature inside the fluidized bed reactor cavity is 500–700℃ and the pressure is 0.2–0.5MPa.

[0024] Preferably, in step S4, the amount of the diluent is 10-15 wt% of the mass of the vaporized coating powder;

[0025] The amount of the coupling agent used is 0.1 to 0.5 wt% of the mass of the vaporized coating powder;

[0026] The drying temperature is 60-100℃ and the time is 30-60 minutes; after drying, it is passed through a 300-450 mesh sieve.

[0027] Preferably, in step S5, the amount of the diluent is 10-15 wt% of the mass of the vaporized coating powder;

[0028] The amount of the binder is 1 to 5 wt% of the mass of the vaporized coating powder;

[0029] The drying temperature is 60-100℃ and the time is 30-60 minutes; after drying, it is passed through a 30-100 mesh sieve.

[0030] Preferably, in S6, the amount of zinc stearate is 0.1 to 0.5 wt% of the granulated powder mass;

[0031] The pressure for compression molding is 600-800 MPa.

[0032] Preferably, the temperature is maintained at 150–200°C for 60–120 minutes.

[0033] The present invention also proposes an iron-silicon-chromium magnetic powder core prepared by the above method.

[0034] Beneficial Effects: This invention utilizes a water-vapor combined atomization method to produce an iron-silicon-chromium alloy powder. This alloy powder is spherical with a smooth surface, few internal pores, fine grains, and no impurities. By reducing the Cr content in the iron-silicon-chromium alloy while adding a small amount of Mn, the core density and permeability are improved while maintaining the DC superposition characteristics essentially unchanged. After passivation treatment, a fluidized bed coating process is employed. The silica generated from the decomposition of low-melting-point silicone resin at high temperature uniformly and tightly coats the powder surface. Compared to simple mechanical coating, this coating is thinner and denser, effectively improving rust prevention. Furthermore, a coupling agent is used to improve the connection between the organic resin and inorganic materials, enhancing the interfacial properties and adhesion of the material after coupling coating. Through the above-mentioned coating process, the low-chromium iron-silicon chromium magnetic powder core of the present invention can achieve the same rust prevention effect as high-chromium cores. Furthermore, with a slight increase in magnetic permeability, the withstand voltage characteristics and insulation resistance are significantly improved. Its effective magnetic permeability is 29-32, insulation resistance is ≥1.5GΩ, and withstand voltage reaches ≥1.3KV. At the same time, the magnetic powder core shows no rust spots after 48 hours of salt spray testing, which can meet the development requirements of miniaturization, high magnetic permeability, and high power of integrally molded inductors. Detailed Implementation

[0035] The raw materials used in the following examples were obtained through purchase: silicone resin was purchased from Dow Corning, model 805, with a molecular weight of 6000-10000 Da; phenolic resin was purchased from Sumitomo, Japan, model PR12603, with a molecular weight of 124 g / mol; polyvinyl alcohol was purchased from Chengdu Chenlong, Sichuan, model 088-50, with a viscosity of 25-30 MPa.s; polyvinyl butyral was purchased from Shanghai Yunhe, model BM-2, with a viscosity of 150 MPa.s; silane coupling agent was purchased from Dow Corning, model OFS-6040, with a molecular weight of 221.37 g / mol; and aluminate coupling agent was purchased from Kangjin, Dongguan, Guangdong, model DL411. The molecular weight is 1350 g / mol; the titanate coupling agent was purchased from Kangjin, Dongguan, Guangdong, model NDZ-201, with a molecular weight of 1310 g / mol; the dimethyl silicone oil was purchased from Dow Corning, model PMX-200, with a viscosity of 10 MPa.s; the amino silicone oil was purchased from Dow Corning, model OFX-8040, with a molecular weight of 1000-10000 Da; the ethyl silicate was purchased from Shuangying, Jinan, Shandong, model industrial grade, with a molecular weight of 208.328 g / mol; the one-component epoxy resin was purchased from Dadong Resin, model 95F, with a molecular weight of 900-1000 Da; and the zinc stearate was purchased from Tianjin Damao, model AR / 500g.

[0036] The technical solution of the present invention will now be described in detail through specific embodiments.

[0037] Example 1

[0038] The preparation of a low-chromium, rust-resistant iron-silicon-chromium magnetic powder core is as follows:

[0039] (1) Alloy smelting: According to the mass percentages of Si 8.0wt%, Cr 1.7wt%, Mn 0.3wt%, and Fe 90.0wt%, the alloy raw materials were deoxidized under nitrogen protection and smelted in a medium frequency induction furnace at 1650℃ for 1 hour.

[0040] (2) Crushing and powdering: After the alloy is smelted, it is directly subjected to water-air combined atomization powdering. The high pressure water pressure is controlled at 120MPa and the high pressure nitrogen pressure is 3MPa. After cooling, the atomized powder is sieved through a 400-mesh sieve to obtain iron-silicon-chromium alloy powder.

[0041] (3) Powder passivation: Take 15% of the mass of iron-silicon-chromium alloy powder, acetone diluent and 0.2% of phosphoric acid passivating agent, mix them, and then slowly add the iron-silicon-chromium alloy powder into it. Stir and mix for 8 minutes, and then transfer it to an oven to dry. The drying temperature is 100℃ and the drying time is 60 minutes. At the same time, the nitrogen atmosphere is turned on and the flow rate is controlled at 300 ml / min. After drying, passivation powder is obtained by sieving through a 400 sieve.

[0042] (4) Vaporization coating: A fluidized bed heating coating process is adopted. Tetraethyl orthosilicate, accounting for 0.2% of the mass of the passivation powder, is used as a vaporization coating agent. The tetraethyl orthosilicate is vaporized by heating. The vaporized tetraethyl orthosilicate is carried by high passivation nitrogen gas at a pressure of 0.3 MPa and then sprayed onto the passivation powder. Insulation coating is then carried out at 600℃. After cooling, the vaporized coated powder is obtained by passing through a 450 mesh.

[0043] (5) Coupling coating: Take 15% of the mass of vaporized coating powder, acetone diluent and 0.2% of silane coupling agent, mix them, and then slowly add the vaporized coating powder into it. Stir and mix for 8 minutes. Then transfer the coated powder into an oven to dry at 80°C for 50 minutes. After drying, sieve it through a 450 mesh to obtain the coupling coating powder.

[0044] (6) Granulation: Take 15% of the mass of the coupling coating powder, acetone diluent and 4% of epoxy resin binder, mix them, and then slowly add the coupling coating powder into it. Stir and mix for 8 minutes. Then transfer the coated powder into the oven to dry. The drying temperature is 80℃ and the drying time is 50 minutes. After drying, sieve through a 100-mesh sieve to obtain granulated powder.

[0045] (7) Compression molding: Add 0.3% zinc stearate by mass to the granulated powder, and perform compression molding. The molding pressure is 800MPa, and the magnetic ring size is 14.8*8*3.5mm. Clean the edges and corners to obtain the blank.

[0046] (8) Heat treatment: Anneal the formed ferromagnetic core blank in an air environment at 180°C and hold for 60 minutes.

[0047] (9) Winding test: The heat-treated magnetic ring is wound with 0.8m enameled wire, 14 turns, and inductance test is performed on each turn.

[0048] Example 2

[0049] (1) Alloy smelting: According to the mass percentages of Si 6.0wt%, Cr 3.8wt%, Mn 0.2wt%, and Fe 90.0wt%, the alloy raw materials were deoxidized under nitrogen protection and smelted in a medium frequency induction furnace at 1670℃ for 1 hour.

[0050] (2) Crushing and powdering: After the alloy is smelted, it is directly subjected to water-air combined atomization powdering. The high pressure water pressure is controlled at 100MPa and the high pressure nitrogen pressure is controlled at 3.5MPa. After cooling, the atomized powder is sieved through a 400-mesh sieve to obtain iron-silicon-chromium alloy powder.

[0051] (3) Powder passivation: Take 12% of anhydrous ethanol diluent and 0.2% of chromic acid passivating agent by weight of iron-silicon-chromium alloy powder, mix them, and then slowly add iron-silicon-chromium alloy powder into it. Stir and mix for 10 minutes, and then transfer it to an oven to dry. The drying temperature is 120℃ and the drying time is 60 minutes. At the same time, the nitrogen atmosphere is turned on and the flow rate is controlled at 300 ml / min. After drying, passivation powder is obtained by sieving through a 400 sieve.

[0052] (4) Vaporization coating: A fluidized bed heating coating process is adopted. Dimethyl silicone oil accounting for 0.3% of the passivation powder mass is used as a vaporization coating agent. The dimethyl silicone oil is vaporized by heating. Under the pressure of high passivation nitrogen gas at 0.4 MPa, the vaporized dimethyl silicone oil is carried towards the passivation powder. Then, insulation coating is performed at 700℃. After cooling, the vaporized coated powder is obtained by passing through a 450 mesh.

[0053] (5) Coupling coating: Take 12% of anhydrous ethanol diluent and 0.2% of aluminate coupling agent by mass of vaporized coating powder, mix them, and then slowly add the vaporized coating powder into it. Stir and mix for 10 minutes. Then transfer the coated powder into an oven to dry at 80°C for 60 minutes. After drying, sieve through a 400-mesh sieve to obtain the coupling coating powder.

[0054] (6) Granulation: Take 12% of anhydrous ethanol diluent and 4% of phenolic resin binder by weight of coupling coating powder, mix them, and then slowly add the coupling coating powder into it. Stir and mix for 10 minutes. Then transfer the coated powder into an oven to dry at 100°C for 60 minutes. After drying, sieve through a 100-mesh sieve to obtain granulated powder.

[0055] (7) Compression molding: Add 0.3% zinc stearate by mass to the granulated powder, and perform compression molding. The molding pressure is 800MPa, and the magnetic ring size is 14.8*8*3.5mm. Clean the edges and corners to obtain the blank.

[0056] (8) Heat treatment: Anneal the formed ferromagnetic core blank in an air environment at 180°C and hold for 60 minutes.

[0057] (9) Winding test: The heat-treated magnetic ring is wound with 0.8m enameled wire, 14 turns, and inductance test is performed on each turn.

[0058] Example 3

[0059] (1) Alloy smelting: According to the mass percentages of Si 3.5wt%, Cr 4.1wt%, Mn 0.4wt%, and Fe 92.0wt%, the alloy raw materials were deoxidized under nitrogen protection and smelted in a medium frequency induction furnace at 1660℃ for 1.5h.

[0060] (2) Crushing and powdering: After the alloy is smelted, it is directly subjected to water-air combined atomization powdering. The high pressure water pressure is controlled at 100MPa and the high pressure nitrogen pressure is 5MPa. After cooling, the atomized powder is sieved through a 400-mesh sieve to obtain iron-silicon-chromium alloy powder.

[0061] (3) Powder passivation: Take 16% of the mass of iron-silicon-chromium alloy powder as ethyl acetate diluent and 0.4% of nitric acid ethanol passivating agent, mix them, and then slowly add the iron-silicon-chromium alloy powder into it. Stir and mix for 12 minutes, and then transfer it to an oven to dry. The drying temperature is 120℃ and the drying time is 100 minutes. At the same time, turn on the nitrogen atmosphere and control the flow rate at 300 ml / min. After drying, passivation powder is obtained by sieving through a 400 mesh.

[0062] (4) Vaporization coating: A fluidized bed heating coating process is adopted. 0.5% of amino silicone oil by mass of passivation powder is used as vaporization coating agent. The amino silicone oil is vaporized by heating. The vaporized amino silicone oil is carried by high passivation nitrogen gas at a pressure of 0.5 MPa and rushed to the passivation powder. Then, insulation coating is carried out at 700℃. After cooling, the vaporized coated powder is obtained by passing through a 450 sieve.

[0063] (5) Coupling coating: Take 14% of the vaporized coating powder by weight of ethyl acetate diluent and 0.4% of titanate coupling agent, mix them, and then slowly add the vaporized coating powder into it. Stir and mix for 12 minutes. Then transfer the coated powder into an oven to dry at 90°C for 40 minutes. After drying, sieve through a 400-mesh sieve to obtain the coupling coating powder.

[0064] (6) Granulation: Take 14% of the mass of the coupling coating powder, ethyl acetate diluent and 4% of polyvinyl butyral binder, mix them, and then slowly add the coupling coating powder into it. Stir and mix for 12 minutes. Then transfer the coated powder into an oven to dry at a temperature of 90°C for 40 minutes. After drying, sieve through a 100-mesh sieve to obtain granulated powder.

[0065] (7) Compression molding: Add 0.3% zinc stearate by mass to the granulated powder, and perform compression molding. The molding pressure is 800MPa, and the magnetic ring size is 14.8*8*3.5mm. Clean the edges and corners to obtain the blank.

[0066] (8) Heat treatment: Anneal the formed ferromagnetic core blank in an air environment at 180°C and hold for 60 minutes.

[0067] (9) Winding test: The heat-treated magnetic ring is wound with 0.8m enameled wire, 14 turns, and inductance test is performed on each turn.

[0068] Comparative Example 1

[0069] The preparation of an iron-silicon-chromium magnetic powder core differs from that in Example 1 only in that it does not contain steps (4) and (5), and the passivation powder is directly subjected to subsequent granulation, molding and heat treatment.

[0070] Comparative Example 2

[0071] The preparation of an iron-silicon-chromium magnetic powder core differs from that in Example 1 only in that: in step (1), the mass percentages of Si 5.5wt%, Cr 5.5wt%, and Fe 89.0wt% are used.

[0072] Comparative Example 3

[0073] The preparation of an iron-silicon-chromium magnetic powder core differs from that in Example 1 only in the following aspects: 1. In step (1), the mass percentages of Si 5.5wt%, Cr 5.5wt%, and Fe 89.0wt% are used; 2. Steps (4) and (5) are not included, and the passivation powder is directly subjected to subsequent granulation, molding and heat treatment.

[0074] Comparative Example 4

[0075] The preparation of an iron-silicon-chromium magnetic powder core differs from that in Example 1 only in that: 1. In step (1), the mass percentages of Si 3.0wt%, Cr 9wt%, and Fe 88.0wt% are used; 2. Steps (4) and (5) are not included, and the passivation powder is directly subjected to subsequent granulation, molding and heat treatment.

[0076] Performance testing

[0077] The performance of the iron-silicon-chromium magnetic powder cores prepared in Examples 1-3 and Comparative Examples 1-4 was tested according to the standard "Q / YAJS10-2011 Standard for Powders for Magnetic Materials". The results are shown in Table 1.

[0078] Table 1. Magnetic property test results of iron-silicon-chromium magnetic powder cores

[0079]

[0080] A comparison of Example 1 and Comparative Example 1 reveals that, in the absence of vaporization and coupling coating, although the effective magnetic permeability is improved, the insulation and withstand voltage characteristics decrease significantly, and a large number of rust spots appear after 48 hours of salt spray testing. A comparison of Example 1 and Comparative Example 2 shows that, under the same coating process, the low-chromium (containing a small amount of Mn) powder in Example 1 exhibits higher magnetic permeability and better insulation and withstand voltage characteristics than the high-chromium powder in Comparative Example 2.

[0081] By comparing the examples and comparative examples, it can be seen that the iron-silicon-chromium magnetic powder core of the present invention has good withstand voltage characteristics, high insulation resistance, and no salt spray rust, while also possessing high magnetic permeability. Furthermore, by changing the content of some elements, the insulation characteristics are significantly improved under the same effective magnetic permeability.

[0082] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for producing a low-chromium anti-rust FeSiCr magnetic powder core, characterized by, Includes the following steps: S1. Raw material selection: The iron-silicon-chromium alloy powder obtained by water-vapor combined atomization powdering has the following composition by mass percentage: Si 3.0~9.0wt%, Cr 1.5~4.5wt%, Mn 0.2-0.5wt%, with the balance being Fe; S2. Powder passivation: After mixing the diluent and the passivating agent, the iron-silicon-chromium alloy powder is added, stirred and mixed, dried under a protective atmosphere, and sieved to obtain passivated powder; the amount of the diluent is 10~20wt% of the mass of the iron-silicon-chromium alloy powder; the amount of the passivating agent is 0.1~0.5wt% of the mass of the iron-silicon-chromium alloy powder; the diluent is one of anhydrous ethanol, ethyl acetate, and acetone; the passivating agent is one or more of chromic acid and phosphoric acid. S3. Vaporization Coating: A fluidized bed heating coating process is adopted, using low melting point organosilicon resin as a vaporization coating agent for coating, followed by cooling and sieving to obtain vaporization coated powder. S4. Coupling Coating: Mix the diluent and coupling agent, add the vaporization coating powder, stir and mix, dry, and sieve to obtain the coupling coating powder; the amount of the diluent is 10-15 wt% of the mass of the vaporization coating powder; the amount of the coupling agent is 0.1-0.5 wt% of the mass of the vaporization coating powder. S5. Granulation: Mix the diluent and binder, add the coupling coating powder, stir and mix, dry, and sieve to obtain granulated powder; S6. Compression molding: Add zinc stearate to the granulated powder, compress and mold, and clean the edges and burrs to obtain the blank; S7. Heat treatment: The blank is annealed in air atmosphere to obtain the final product.

2. The method of claim 1, wherein, The vaporization coating agent is one or more of dimethyl silicone oil, amino silicone oil, and ethyl silicate. The coupling agent is one of silane coupling agents, aluminate coupling agents, and titanate coupling agents; The adhesive is one or more of phenolic resin, epoxy resin, polyvinyl alcohol, and polyvinyl butyral.

3. The method according to claim 1 or 2, characterized in that, In S1, the iron-silicon-chromium alloy powder passes through a 300-500 mesh sieve.

4. The method according to any one of claims 1-2, characterized in that, In S2, the drying temperature is 100~150℃ and the time is 60~120min; after drying, it is passed through a 300~500 mesh sieve.

5. The method according to any of claims 1-2, characterized in that, In S3, the amount of the low-melting-point silicone resin is 0.1~1.0% of the mass of the passivation powder; In the fluidized bed heating and coating process, the temperature inside the fluidized bed reactor cavity is 500~700℃ and the pressure is 0.2~0.5MPa.

6. The method according to any one of claims 1-2, characterized in that, In S4, the drying temperature is 60~100℃ and the time is 30~60min; after drying, it is passed through a 300~450 mesh sieve.

7. The method according to any one of claims 1-2, characterized in that, In step S5, the amount of the diluent used is 10-15 wt% of the mass of the vaporized coating powder; The amount of the binder is 1-5 wt% of the mass of the vaporized coating powder; The drying temperature is 60~100℃ and the time is 30~60min; after drying, it is passed through a 30~100 mesh sieve.

8. The method according to any one of claims 1-2, characterized in that, In S6, the amount of zinc stearate used is 0.1~0.5 wt% of the granulated powder mass; The pressure for compression molding is 600~800MPa.

9. The method according to any one of claims 1-2, characterized in that, In S7, keep warm at 150~200℃ for 60~120 minutes.

10. An iron-silicon-chromium magnetic powder core prepared by the method described in any one of claims 1-9.

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