Preparation method of composite magnetic powder core of iron-nickel doped carbonyl iron powder

Abstract

The invention discloses a preparation method of a composite magnetic powder core of iron-nickel doped carbonyl iron powder, and belongs to the technical field of metal soft magnetic composite magnetic powder cores, the preparation method comprises the following steps: preparing spherical iron-nickel magnetic powder through a gas atomization method; processing the spherical iron-nickel magnetic powder by using a coupling agent to obtain modified spherical iron-nickel magnetic powder; and adding the modified spherical iron-nickel magnetic powder, carbonyl iron powder, kaolin, a binder and a release agent into a V-shaped stirrer, uniformly mixing to obtain mixed magnetic powder, pressing the mixed magnetic powder into a magnetic ring, performing annealing treatment in a nitrogen atmosphere, and performing furnace cooling to room temperature. According to the method, the high-sphericity-degree iron-nickel magnetic powder is firstly produced through a gas atomization method, then large pores among iron-nickel particles are filled with small carbonyl iron particles, and finally the magnetic core density is improved, so that the relative permeability and the direct-current bias performance of a composite magnetic powder core sample are improved; in addition, due to the fact that the nickel metal raw material is high in cost, the raw material cost for preparing the iron-nickel composite magnetic powder core is reduced through doping of the carbonyl iron powder.

Description

Technical Field

[0001] The invention belongs to the technical field of metal soft magnetic composite magnetic powder cores, and in particular relates to a method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder. Background Art

[0002] Metal soft magnetic powder cores have the advantages of high saturation magnetic induction intensity, high Curie temperature and high DC superposition performance, and are widely used in high current power devices. Among them, the DC superposition performance of iron-nickel soft magnetic powder cores is the best, and it has the advantages of high saturation magnetic induction intensity, high Curie temperature, low magnetostriction coefficient (low noise) and low cost, so it has a large market capacity.

[0003] Chinese patent application number 201110133772.9 discloses an iron-nickel alloy soft magnetic material with a magnetic permeability of μ=125 and a method for manufacturing the same. It proposes a method of treating iron-nickel powder with phosphoric acid to obtain an iron-nickel magnetic powder core material with high magnetic permeability. Specifically, a phosphate oxide layer is generated on the surface of the magnetic powder to increase the surface resistance of the magnetic powder and reduce the loss.

[0004] Chinese patent application number 201610693252.6 discloses a method for preparing an iron-nickel metal magnetic powder core, and proposes coating a certain amount of kaolin on the surface of the iron-nickel magnetic powder by ball milling to reduce losses.

[0005] For the former, the phosphate generated by phosphoric acid passivation is not resistant to high temperatures and is easily decomposed at 570°C. In addition, due to the corrosion of the surface of the spherical magnetic powder, excessive pressure during the pressing process will cause the sphericity of the magnetic powder to be destroyed, the shape anisotropy of the iron-nickel magnetic powder will increase, and the magnetic properties of the iron-nickel magnetic powder will be reduced. For the latter, since the coating agent is a non-magnetic material, it can reduce the loss of the composite iron-nickel magnetic powder core, but the magnetic permeability will be lower than that of the original powder. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder, so as to solve the problem of poor magnetic properties of the iron-nickel magnetic powder core in the prior art.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder comprises the following steps:

[0009] S1. preparing spherical iron-nickel magnetic powder by gas atomization method;

[0010] S2, treating the spherical iron-nickel magnetic powder with a coupling agent to obtain modified spherical iron-nickel magnetic powder;

[0011] S3. Add modified spherical iron-nickel magnetic powder, carbonyl iron powder, kaolin, binder and release agent into a V-type mixer, mix evenly to obtain mixed magnetic powder, press the mixed magnetic powder into a magnetic ring, anneal it in a nitrogen atmosphere, cool it to room temperature with the furnace, and obtain a composite magnetic powder core of iron-nickel doped carbonyl iron powder.

[0012] Among them, the amount of carbonyl iron powder is 5-15% of the mass of the modified spherical iron-nickel magnetic powder, the amount of kaolin is 0.5% of the total mass of the modified spherical iron-nickel magnetic powder and the carbonyl iron powder, the amount of binder is 0.4% of the total mass of the modified spherical iron-nickel magnetic powder and the carbonyl iron powder, and the amount of release agent is 0.4% of the total mass of the modified spherical iron-nickel magnetic powder and the carbonyl iron powder.

[0013] As a preferred technical solution of the present invention, the preparation process of the spherical iron-nickel magnetic powder is as follows:

[0014] The iron ingot and the nickel ingot are placed in a medium frequency induction furnace and heated to 1650°C at a power of 300kW. After the iron ingot and the nickel ingot are completely melted, a slag-making agent is added to remove the slag. The iron-nickel solution after the slag is removed is atomized with high-pressure nitrogen to obtain spherical iron-nickel magnetic powder.

[0015] As a preferred technical solution of the present invention, the mass ratio of the iron ingot to the nickel ingot is 58:42.

[0016] As a preferred technical solution of the present invention, the slag-forming agent is sodium pyrosulfate and / or limestone.

[0017] As a preferred technical solution of the present invention, the amount of the slag-forming agent is 0.1-0.3% of the total mass of the iron ingot and the nickel ingot.

[0018] As a preferred technical solution of the present invention, the atomization pressure is 15-30MPa.

[0019] As a preferred technical solution of the present invention, the preparation process of the modified spherical iron-nickel magnetic powder is as follows:

[0020] Dissolve the coupling agent in acetone, then add spherical iron-nickel magnetic powder, stir evenly, dry, and pass through an 80-mesh sieve.

[0021] As a preferred technical solution of the present invention, the amount of the coupling agent is 0.1-0.2% of the mass of the spherical iron-nickel magnetic powder, and the amount ratio of acetone to the spherical iron-nickel magnetic powder is 0.9-1.1 mL: 10 g.

[0022] As a preferred technical solution of the present invention, the coupling agent is at least one of KH-550, KH-560, KH-570, a titanate coupling agent and an aluminate coupling agent, preferably KH-550.

[0023] As a preferred technical solution of the present invention, the binder is silicone resin and / or epoxy resin, preferably German Wacker silicone resin SI LRESMSE-100.

[0024] As a preferred technical solution of the present invention, the release agent is at least one of zinc stearate, magnesium stearate, calcium stearate and aluminum stearate, preferably zinc stearate.

[0025] As a preferred technical solution of the present invention, the annealing temperature is 500-700° C. and the annealing time is 1 hour.

[0026] As a preferred technical solution of the present invention, the pressure during the magnetic ring pressing process is 1823 MPa.

[0027] Beneficial effects of the present invention:

[0028] 1. The present invention provides a method for preparing a composite magnetic powder core of iron-nickel doped with carbonyl iron powder, wherein high sphericity iron-nickel magnetic powder is first produced by an atomization method, and then the larger pores between the iron-nickel particles are filled with small carbonyl iron particles, thereby finally improving the density of the magnetic core and thus improving the relative magnetic permeability of the composite magnetic powder core sample. At the same time, the iron-nickel magnetic powder core doped with carbonyl iron powder has excellent DC bias performance; in addition, since the cost of nickel metal raw materials is high, the doping of carbonyl iron powder reduces the cost of raw materials for preparing the magnetic powder core.

[0029] 2. The present invention strictly controls the mass ratio of the modified spherical iron-nickel magnetic powder and the carbonyl iron powder. If the content of the carbonyl iron powder is too low, the magnetic property improvement effect of the iron-nickel magnetic powder is not obvious. If the content of the carbonyl iron powder is too high, doping will cause a sharp increase in loss.

[0030] 3. The present invention utilizes a coupling agent to modify the spherical iron-nickel magnetic powder, which is beneficial to improving the adhesion between the spherical iron-nickel magnetic powder and the binder. Not only the coupling modification treatment, but also the spherical iron-nickel magnetic powder cannot be pressed into shape or the molding effect is poor. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below in conjunction with the accompanying drawings.

[0032] Figure 1 is the X-ray diffraction pattern of the composite magnetic powder core obtained in Comparative Example 1 and Example 3 of the present invention;

[0033] Figure 2 1 is a graph showing the magnetic loss test results of the composite magnetic powder cores obtained in Examples 1 to 3 of the present invention and Comparative Examples 1 to 2 at different magnetic induction intensities;

[0034] Figure 3 This is a SEM image of the composite magnetic powder core obtained in Comparative Example 1 of the present invention.

[0035] Figure 4This is a SEM image of the composite magnetic powder core obtained in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] In the present application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, a~b (i.e. a and b), a~c, b~c, or a~b~c, where a, b, c can be single or multiple, respectively.

[0038] The terms used in the embodiments of the present application are only for the purpose of describing specific implementation rules, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the implementation rules of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0039] It should be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of this application.

[0040] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0041] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0042] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0043] The present invention provides a method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder, comprising the following steps:

[0044] S1. preparing spherical iron-nickel magnetic powder by gas atomization method;

[0045] S2, treating the spherical iron-nickel magnetic powder with a coupling agent to obtain modified spherical iron-nickel magnetic powder;

[0046] S3. Add modified spherical iron-nickel magnetic powder, carbonyl iron powder, kaolin, binder and release agent into a V-type mixer, mix evenly to obtain mixed magnetic powder, press the mixed magnetic powder into a magnetic ring, anneal it in a nitrogen atmosphere, and then cool it to room temperature with the furnace to obtain a composite magnetic powder core of iron-nickel doped carbonyl iron powder.

[0047] Among them, the amount of carbonyl iron powder is 5-15% of the mass of the modified spherical iron-nickel magnetic powder. In the exemplary embodiment, it can be a typical but non-restrictive mass proportion such as 5%, 8%, 10%, 12%, 15%, or a range between any two mass proportions. In this case, the carbonyl iron powder has a significant effect on improving the magnetic properties of the iron-nickel magnetic powder without causing a sharp increase in loss.

[0048] The amount of kaolin is 0.5% of the total mass of the modified spherical iron-nickel magnetic powder and the carbonyl iron powder, the amount of the binder is 0.4% of the total mass of the modified spherical iron-nickel magnetic powder and the carbonyl iron powder, and the amount of the release agent is 0.4% of the total mass of the modified spherical iron-nickel magnetic powder and the carbonyl iron powder.

[0049] The preparation process of the spherical iron-nickel magnetic powder is as follows:

[0050] The iron ingot and the nickel ingot are placed in a medium frequency induction furnace and heated to 1650°C at a power of 300kW. After the iron ingot and the nickel ingot are completely melted, a slag-making agent is added to remove the slag. The iron-nickel solution after the slag is removed is atomized with high-pressure nitrogen to obtain spherical iron-nickel magnetic powder.

[0051] The mass ratio of the iron ingot to the nickel ingot is 58:42.

[0052] The slagging agent is sodium pyrosulfate and / or limestone.

[0053] The dosage of the slag-forming agent is 0.1-0.3% of the total mass of the iron ingot and the nickel ingot.

[0054] The atomization pressure is 15-30 MPa.

[0055] The preparation process of the modified spherical iron-nickel magnetic powder is as follows:

[0056] Dissolve the coupling agent in acetone, then add spherical iron-nickel magnetic powder, stir evenly, dry, and pass through an 80-mesh sieve.

[0057] The amount of the coupling agent is 0.1-0.2% of the mass of the spherical iron-nickel magnetic powder, and the amount ratio of acetone to the spherical iron-nickel magnetic powder is 0.9-1.1 mL: 10 g.

[0058] The coupling agent is at least one of KH-550, KH-560, KH-570, a titanate coupling agent, and an aluminate coupling agent, preferably KH-550.

[0059] The binder is silicone resin and / or epoxy resin, preferably German Wacker silicone resin SILRESMSE-100.

[0060] The release agent is at least one of zinc stearate, magnesium stearate, calcium stearate and aluminum stearate, preferably zinc stearate.

[0061] The annealing temperature is 500-700° C., and the annealing time is 1 hour.

[0062] The pressure during the magnetic ring pressing process is 1823 MPa.

[0063] Example 1

[0064] A method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder comprises the following steps:

[0065] S1. Place the iron ingot and the nickel ingot in a medium frequency induction furnace at a mass ratio of 58:42, heat the furnace to 1650°C at a power of 300kW, add a slag-making agent to remove the slag after the iron ingot and the nickel ingot are completely melted, and atomize the iron-nickel solution after the slag removal with high-pressure nitrogen at an atomization pressure of 15MPa to obtain spherical iron-nickel magnetic powder;

[0066] S2, 0.5g KH-550 was dissolved in 45mL acetone, and then 500g spherical iron-nickel magnetic powder was added, and the mixture was dried after being stirred evenly, and passed through an 80-mesh sieve to obtain modified spherical iron-nickel magnetic powder;

[0067] S3. Add 475g of modified spherical iron-nickel magnetic powder, 25g of carbonyl iron powder, 2.5g of kaolin, 2g of silicone resin S ILRESMSE-100, and 2g of zinc stearate into a V-type blender and mix well to obtain a mixed magnetic powder. Press 31g of the mixed magnetic powder under 1823MPa into a magnetic ring with an outer diameter of 27mm, an inner diameter of 14.9mm, and a height of 11.2mm. Anneal the ring under a nitrogen atmosphere at a temperature of 600°C for 1h. Cool the ring to room temperature with the furnace to obtain a composite magnetic powder core of iron-nickel doped carbonyl iron powder.

[0068] The slag-forming agent is sodium pyrosulfate, and the amount of the slag-forming agent is 0.1% of the total mass of the iron ingot and the nickel ingot.

[0069] Example 2

[0070] A method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder comprises the following steps:

[0071] S1. Place the iron ingot and the nickel ingot in a medium frequency induction furnace at a mass ratio of 58:42, heat the furnace to 1650°C at a power of 300kW, add a slag-making agent to remove the slag after the iron ingot and the nickel ingot are completely melted, and atomize the iron-nickel solution after the slag removal with high-pressure nitrogen at an atomization pressure of 20MPa to obtain spherical iron-nickel magnetic powder;

[0072] S2, 0.8g KH-550 was dissolved in 50mL acetone, and then 500g spherical iron-nickel magnetic powder was added, and the mixture was dried after being stirred evenly, and passed through an 80-mesh sieve to obtain modified spherical iron-nickel magnetic powder;

[0073] S3. Add 450g of modified spherical iron-nickel magnetic powder, 50g of carbonyl iron powder, 2.5g of kaolin, 2g of silicone resin S ILRESMSE-100, and 2g of zinc stearate into a V-type blender and mix well to obtain a mixed magnetic powder. Press 31g of the mixed magnetic powder into a magnetic ring with an outer diameter of 27mm, an inner diameter of 14.9mm, and a height of 11.2mm at 1823MPa. Anneal the ring in a nitrogen atmosphere at a temperature of 600°C for 1h. Cool the ring to room temperature with the furnace to obtain a composite magnetic powder core of iron-nickel doped carbonyl iron powder.

[0074] The slag-forming agent is limestone, and the amount of the slag-forming agent is 0.2% of the total mass of the iron ingot and the nickel ingot.

[0075] Example 3

[0076] A method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder comprises the following steps:

[0077] S1. Place the iron ingot and the nickel ingot in a medium frequency induction furnace at a mass ratio of 58:42, heat the furnace to 1650°C at a power of 300kW, add a slag-making agent to remove the slag after the iron ingot and the nickel ingot are completely melted, and atomize the iron-nickel solution after the slag removal with high-pressure nitrogen at an atomization pressure of 30MPa to obtain spherical iron-nickel magnetic powder;

[0078] S2, dissolving 1g KH-550 in 45mL acetone, then adding 500g spherical iron-nickel magnetic powder, stirring evenly and drying, passing through an 80-mesh sieve to obtain modified spherical iron-nickel magnetic powder;

[0079] S3. Add 475g of modified spherical iron-nickel magnetic powder, 25g of carbonyl iron powder, 2.5g of kaolin, 2g of silicone resin S ILRESMSE-100, and 2g of zinc stearate into a V-type blender and mix well to obtain a mixed magnetic powder. Press 31g of the mixed magnetic powder under 1823MPa into a magnetic ring with an outer diameter of 27mm, an inner diameter of 14.9mm, and a height of 11.2mm. Anneal the ring under a nitrogen atmosphere at a temperature of 600°C for 1h. Cool the ring to room temperature with the furnace to obtain a composite magnetic powder core of iron-nickel doped carbonyl iron powder.

[0080] The slag-forming agent is sodium pyrosulfate and / or limestone, and the amount of the slag-forming agent is 0.3% of the total mass of the iron ingot and the nickel ingot.

[0081] Comparative Example 1

[0082] A method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder, compared with Example 1, the only difference is that no carbonyl iron powder is added.

[0083] Comparative Example 2

[0084] A method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder, compared with Example 3, the only difference is that the amount of carbonyl iron powder added is adjusted from 75g to 100g ， The amount of modified spherical iron-nickel magnetic powder was adjusted from 475g to 400g.

[0085] Comparative Example 3

[0086] A method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder, compared with Example 1, the only difference is that step S2 is not performed, that is, the specific operation of S3 is:

[0087] 500 g of spherical iron-nickel magnetic powder, 75 g of carbonyl iron powder, 0.25 g of kaolin, 0.4 g of silicone resin SI LRESMSE-100, and 0.4 g of release agent were added into a V-type blender and mixed evenly to obtain a mixed magnetic powder. 31 g of the mixed magnetic powder was pressed into a magnetic ring with an outer diameter of 27 mm, an inner diameter of 14.9 mm, and a height of 11.2 mm at 1823 MPa. The ring was annealed in a nitrogen atmosphere at a temperature of 500°C for 1 h. The ring was cooled to room temperature with the furnace to obtain a composite magnetic powder core of iron-nickel doped carbonyl iron powder.

[0088] In Comparative Example 3, the composite magnetic powder core does not undergo coupling treatment on the spherical iron-nickel magnetic powder, resulting in the inability to press-form the magnetic ring.

[0089] X-ray diffraction was used to characterize the phase of the composite magnetic powder core of iron-nickel doped carbonyl iron powder obtained in Example 3 and Comparative Example 1. The results are as follows: Figure 1 As shown by Figure 1It can be seen that compared with Comparative Example 1, Example 3 has a carbonyl iron peak, indicating that carbonyl iron is successfully incorporated into the nickel-iron magnetic powder.

[0090] The magnetic loss of the composite magnetic powder cores of Examples 1-3 and Comparative Examples 1-2 at different magnetic induction intensities was detected using a BH analyzer (SY-8218) produced by Iwatsu. The relationship between the loss and the magnetic induction intensity at a frequency of 100 kHz was as follows: Figure 2 As shown, Figure 2 Wherein FeNi represents comparative example 1, FeNi+5% carbonyl iron represents embodiment 1, FeNi+10% carbonyl iron represents embodiment 2, FeNi+15% carbonyl iron represents embodiment 1, and FeNi+15% carbonyl iron represents comparative example 2. Figure 2 It can be seen that the doping amount of carbonyl iron powder is 5%-15% with small loss and high magnetic permeability, while the doping amount greater than 15% will cause a sharp increase in loss.

[0091] The inductance of the composite magnetic powder core samples obtained in Examples 1-3 and Comparative Examples 1-2 of the samples was measured using the TH2816B precision LCR digital bridge produced by Tonghui, and the relative magnetic permeability and DC bias performance were calculated. The results are shown in Tables 1 and 2:

[0092] Table 1 Magnetic loss table of composite magnetic powder core samples of Examples 1-3 and Comparative Examples 1-2

[0093] project Inductance L(uH) Relative magnetic permeability u Example 1 46.08 73.34 Example 2 46.24 74.29 Example 3 46.88 76.18 Comparative Example 1 44.8 73.35 Comparative Example 2 47.84 76.83

[0094] It can be seen from Table 1 that the composite magnetic powder cores obtained in Examples 1-3 have good magnetic properties. Specifically, it can be seen from the test results of Example 1 and Comparative Example 1 that the carbonyl iron powder doping improves the relative magnetic permeability of the composite magnetic powder core sample. It can be seen from the test results of Example 3 and Comparative Example 2 that the carbonyl iron powder content is too high and doping will cause a sharp increase in loss.

[0095] Table 2 DC bias performance of composite magnetic powder core samples of Examples 1-3 and Comparative Examples 1-2

[0096]

[0097] It can be seen from Table 2 that compared with Comparative Example 1 and Comparative Example 2, the DC bias performance of the iron-nickel magnetic powder core doped with carbonyl iron powder obtained in Examples 1-3 is more superior.

[0098] The morphology of the composite magnetic powder core samples obtained in Example 3 and Comparative Example 1 was observed. Figure 3 and Figure 4 As shown, Figure 3 This is the SEM image of the composite magnetic powder core obtained in Comparative Example 1. Figure 3 is a SEM image of the composite magnetic powder core obtained in Example 3 of the present invention, Figure 3 It can be seen that the composite magnetic powder core has good sphericity and small magnetic anisotropy. Figure 4 It can be seen that the small particles fill the larger pores between the Fe-Ni particles, increasing the density of the magnetic core and thus increasing the relative magnetic permeability of the composite magnetic powder core sample.

[0099] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0100] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder, characterized in that: The following steps are involved: S1. preparing spherical iron-nickel magnetic powder by gas atomization method; S2, treating the spherical iron-nickel magnetic powder with a coupling agent to obtain modified spherical iron-nickel magnetic powder; S3. Evenly mix the modified spherical iron-nickel magnetic powder, carbonyl iron powder, kaolin, a binder, and a release agent to obtain a mixed magnetic powder. Press the mixed magnetic powder into a magnetic ring, anneal it in a nitrogen atmosphere, and then cool it to room temperature in a furnace to obtain a composite magnetic powder core of iron-nickel doped carbonyl iron powder.

2. The method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder according to claim 1, characterized in that: The amount of the carbonyl iron powder is 5-15% of the mass of the modified spherical iron-nickel magnetic powder, the amount of the kaolin is 0.5% of the total mass of the modified spherical iron-nickel magnetic powder and the carbonyl iron powder, the amount of the binder is 0.4% of the total mass of the modified spherical iron-nickel magnetic powder and the carbonyl iron powder, and the amount of the release agent is 0.4% of the total mass of the modified spherical iron-nickel magnetic powder and the carbonyl iron powder.

3. The method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder according to claim 1, characterized in that: The preparation process of the spherical iron-nickel magnetic powder is as follows: The iron ingot and the nickel ingot are placed in a medium frequency induction furnace and heated to 1650°C at a power of 300kW. After the iron ingot and the nickel ingot are completely melted, a slag-making agent is added to remove the slag. The iron-nickel solution after the slag is removed is atomized with high-pressure nitrogen to obtain spherical iron-nickel magnetic powder.

4. The method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder according to claim 3, characterized in that: The mass ratio of the iron ingot to the nickel ingot is 58:42, and the atomization pressure is 15-30 MPa.

5. The method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder according to claim 1, characterized in that: The preparation process of the modified spherical iron-nickel magnetic powder is as follows: Dissolve the coupling agent in acetone, then add spherical iron-nickel magnetic powder, stir evenly, dry, and pass through an 80-mesh sieve.

6. The method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder according to claim 5, characterized in that: The amount of the coupling agent is 0.1-0.2% of the mass of the spherical iron-nickel magnetic powder, and the amount ratio of acetone to the spherical iron-nickel magnetic powder is 0.9-1.1 mL: 10 g.

7. The method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder according to claim 5, characterized in that: The coupling agent is at least one of KH-550, KH-560, KH-570, a titanate coupling agent and an aluminate coupling agent.

8. The method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder according to claim 1, characterized in that: The adhesive is silicone resin and / or epoxy resin.

9. The method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder according to claim 1, characterized in that: The release agent is at least one of zinc stearate, magnesium stearate, calcium stearate and aluminum stearate.

10. The method for preparing a composite magnetic powder core of iron-nickel doped carbonyl iron powder according to claim 1, characterized in that: The annealing temperature is 500-700° C., and the annealing time is 1 hour.

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