Preparation method of iron-based composite magnetic powder core

Abstract

The present invention provides a preparation method of an iron-based composite magnetic powder core. After wet grinding and pretreatment of flaky iron-based alloy powder, first spherical iron-based alloy powder and silane coupling agent, operations such as screening, first annealing treatment, passivation treatment, insulation coating treatment, mixing with a release agent, pressing, second annealing treatment and surface spraying of insulating paint are carried out in sequence, and an iron-based composite magnetic powder core with high magnetic permeability and low magnetic loss is prepared. The preparation method of the present invention has a relatively low production cost and a simple preparation process, and has a prospect of large-scale popularization and application.

Description

Technical Field

[0001] The present invention relates to the technical field of soft magnetic materials, and particularly to a preparation method of an iron-based composite magnetic powder core. Background Art

[0002] Metal magnetic powder cores are powders made of metal or alloy soft magnetic materials, and are soft magnetic materials with good comprehensive properties formed through special processes. They have some excellent characteristics of metal soft magnets and ferrite soft magnets, with relatively small magnetic permeability but good linearity, high saturation magnetic flux density, and a wide working frequency range, which is of extremely important significance for the development of electronic products towards high precision, high sensitivity, large capacity, and miniaturization, and is also a key basic material for preparing electronic components.

[0003] The soft magnetic powder cores applied on the market mainly include metal soft magnetic powder cores (iron powder cores, iron-silicon powder cores, iron-silicon-aluminum powder cores, iron-nickel powder cores), amorphous, nanocrystalline, and ferrite powder cores. Alloy soft magnetic materials have characteristics such as high magnetic permeability, high magnetic induction intensity, and excellent DC superposition performance, but have low resistivity; at high frequencies, due to the sharp increase in eddy current loss with the increase in frequency, they cannot be used. Among alloy magnetic powder cores, the most commonly used is the iron-silicon-aluminum magnetic powder core. The iron-silicon-aluminum magnetic powder core has good high-frequency magnetic properties, temperature stability, wide constant permeability, low loss, near-zero magnetostriction, and low cost, etc.

[0004] With the increasingly serious shortage and dependence on energy worldwide, it is necessary to improve the efficiency of energy conversion to reduce energy consumption. This requires low loss of magnetic powder cores, high magnetic induction intensity, and low cost at the same time, which is the future development direction of metal magnetic powder cores. As the working frequency of magnetic powder core applications is getting higher and higher, the main problem of such products lies in how to balance the high magnetic permeability and low loss of the magnetic core.

[0005] CN100490029A discloses a composite powder for magnetic powder cores and a preparation method thereof. Two annealed amorphous nanocrystalline magnetic powders are uniformly mixed and subjected to insulation bonding treatment, and then pressed into a magnetic core and annealed to obtain a magnetic powder core with comprehensive characteristics. The magnetic powder core prepared by this method is relatively expensive, the preparation process takes a long time, and the cost increases.

[0006] CN101118797A discloses a composite powder for magnetic powder cores, a magnetic powder core, and their preparation methods. The magnetic powder core composite powder is composed of 50-96wt% iron-based soft magnetic powder and 4-50wt% iron-based amorphous soft magnetic powder with different required characteristics and high insulation performance, and is uniformly mixed to prepare a magnetic powder core with comprehensive and all-round required characteristics, with low loss characteristics and improved magnetic permeability characteristics at the same time.

[0007] CN105185560A discloses a preparation method of an iron-based metal soft magnetic powder core. In this method, iron-based flaky metal soft magnetic powder is used as the raw material powder for annealing treatment, followed by passivation and insulation coating. After drying, it is pressed into a powder core, and finally, through annealing and painting treatments, the finished powder core is obtained. This powder core has a high density, good mechanical strength, high magnetic permeability, high quality factor, and low loss.

[0008] However, the density of the powder core blank obtained by the above method is relatively low, there are pores in the internal air gap, and the magnetic permeability needs to be further improved.

[0009] Therefore, it is of great significance to develop a preparation method of an iron-based composite magnetic powder core with a high density of the blank, high magnetic permeability, and low magnetic loss. Summary of the Invention

[0010] To solve the above technical problems, the present invention provides a preparation method of an iron-based composite magnetic powder core. Flaky alloy powder and spherical alloy powder are used to prepare the powder core. While improving the density of the blank, the pores inside the powder core are reduced, and the loss of the powder core is lowered. The preparation method has a relatively low production cost, a simple preparation process, low equipment requirements, and the prepared powder core has better performance.

[0011] To achieve this purpose, the present invention adopts the following technical solutions:

[0012] In the first aspect, the present invention provides a preparation method of an iron-based composite magnetic powder core, and the preparation method includes the following steps:

[0013] (1) The flaky iron-based alloy powder, the first spherical iron-based alloy powder, and the silane coupling agent are successively subjected to wet grinding pretreatment, sieving separation, and drying to obtain the first powder;

[0014] (2) After the first powder and the second spherical iron-based alloy powder are independently subjected to the first annealing treatment, passivation treatment, and insulation coating treatment respectively, they are mixed with the binder and subjected to sieving and granulation treatment to obtain the granulated flaky powder and the granulated spherical powder respectively;

[0015] (3) After the granulated flaky powder and the granulated spherical powder are independently mixed with the release agent, they are filled into the mold cavity in the order of flaky powder - spherical powder - flaky powder and pressed into a magnetic core blank;

[0016] (4) After the magnetic core blank is subjected to the second annealing treatment, an insulating paint is sprayed on its surface to obtain the iron-based composite magnetic powder core.

[0017] The preparation method of the iron-based composite magnetic powder core described in the present invention pre-treats flaky iron-based alloy powder, first spherical iron-based alloy powder and silane coupling agent by wet grinding to make the first spherical iron-based alloy powder flaky. After that, it is sieved, separated and dried to obtain a first powder with an average particle size D50 of 20-200 μm, which improves the density of the prepared iron-based composite magnetic powder core, has a higher magnetic permeability at the same time, and can maintain the performance of lower loss. Among them, the role of the silane coupling agent is that after the first annealing treatment, it decomposes to generate silicon dioxide to coat the surfaces of the first powder and the second spherical iron-based alloy powder, making the powder flow better; moreover, it prevents the powder from being rusted in the air. In step (3), the magnetic core blank is pressed by filling the mold cavity in the order of flaky powder - spherical powder - flaky powder. The main reason is that the magnetic permeability of the flaky powder is higher than that of the spherical powder. Pressing in the order of flaky powder - spherical powder - flaky powder can greatly increase the magnetic permeability of the obtained iron-based composite magnetic powder core at most.

[0018] Preferably, the iron-based alloy powder in step (1) includes any one or at least two combinations of FeSi, FeNi, FeSiAl, FeNiMo, FeSiAlNi, FeSiCr or FeSiAlTi. Among them, typical but non-limiting combinations include the combination of FeSi and FeNi, the combination of FeSiAl and FeNiMo, the combination of FeSiAlNi and FeSiCr, the combination of FeSiAlTi, FeSi, FeNi and FeSiAl, or the combination of FeNiMo, FeSiAlNi and FeSiCr.

[0019] Preferably, the flaky iron-based alloy powder is sieved through a 50-150 mesh sieve before wet grinding pretreatment. For example, it can be 50 mesh, 60 mesh, 70 mesh, 80 mesh, 90 mesh or 100 mesh, etc., but it is not limited to the listed values. Other unlisted values within this value range are equally applicable.

[0020] Preferably, the first spherical iron-based alloy powder is sieved through a 300-500 mesh sieve before wet grinding pretreatment. For example, it can be 300 mesh, 350 mesh, 400 mesh or 500 mesh, etc., but it is not limited to the listed values. Other unlisted values within this value range are equally applicable.

[0021] Preferably, the mass parts of the flaky iron-based alloy powder, the first spherical iron-based alloy powder, and the silane coupling agent are 5-20 parts, 80-95 parts, and 0.5-5 parts respectively; among them, the flaky iron-based alloy powder is 5-20 parts, for example, it can be 5 parts, 8 parts, 10 parts, 15 parts, or 20 parts, etc., but is not limited to the listed values, and other unlisted values within this value range are equally applicable; the spherical iron-based alloy powder is 80-95 parts, for example, it can be 80 parts, 83 parts, 85 parts, 90 parts, or 95 parts, etc., but is not limited to the listed values, and other unlisted values within this value range are equally applicable; the silane coupling agent is 0.5-5 parts, for example, it can be 0.5 parts, 0.7 parts, 1.0 parts, 1.5 parts, or 2 parts, etc., but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0022] Preferably, the solvents used in the wet grinding pretreatment in step (1) include alcohol and / or acetone.

[0023] Preferably, the time of the wet grinding pretreatment is 1-5 h, for example, it can be 1 h, 2 h, 3 h, 4 h, 4.5 h, or 5 h, etc., but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0024] Preferably, the rotational speed frequency of the wet grinding pretreatment is 20-30 Hz, for example, it can be 20 Hz, 21 Hz, 23 Hz, 25 Hz, 27 Hz, or 30 Hz, etc., but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0025] Preferably, the average particle size D50 of the first powder is 20-200 μm, for example, it can be 20 μm, 30 μm, 50 μm, 80 μm, 90 μm, 100 μm, or 200 μm, etc., but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0026] Preferably, in the first annealing treatment in step (2), the temperature is raised to 550-700°C at a heating rate of 1-5°C / min under nitrogen protection, held for 1-3 h, and then cooled to room temperature. The heating rate is 1-5°C / min, for example, it can be 1°C / min, 2°C / min, 3°C / min, 4°C / min, 4.5°C / min or 5°C / min, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable; the temperature is raised to 550-700°C, for example, it can be 550°C, 580°C, 600°C, 650°C or 700°C, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable; held for 1-3 h, for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 2.8 h or 3 h, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0027] Preferably, the passivating agent used in the passivation treatment in step (2) includes any one or a combination of at least two of phosphoric acid, boric acid, hydrogen peroxide or nitric acid. Typical but non-limiting combinations include a combination of phosphoric acid and boric acid, a combination of hydrogen peroxide and nitric acid, or a combination of phosphoric acid, hydrogen peroxide and the like.

[0028] Preferably, the total mass of the passivating agent is 0.1-3 wt% of the total mass of the powder. For example, it can be 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 2 wt% or 3 wt%, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0029] Preferably, the insulating agent used in the insulating coating treatment includes any one or a combination of at least two of silicate, phosphate, mica powder or kaolin. Typical but non-limiting combinations include a combination of silicate and phosphate, a combination of mica powder and kaolin silicate, a combination of phosphate and mica powder, or a combination of kaolin, silicate and phosphate. Preferably, it is any one or a combination of at least two of SiO2, CaO or Al2O3. Typical but non-limiting combinations include a combination of SiO2 and CaO, a combination of Al2O3 and SiO2, or a combination of CaO, Al2O3 and SiO2.

[0030] Preferably, the addition amount of the insulating agent is 0.1-5 wt% of the total mass of the powder. For example, it can be 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt% or 5 wt%, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0031] Preferably, after the insulating coating treatment in step (2), drying is carried out.

[0032] Preferably, the drying temperature is 70 to 140 °C, for example, it can be 70 °C, 80 °C, 90 °C, 100 °C, 120 °C or 140 °C, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0033] Preferably, the adhesive in step (2) includes an organic adhesive or an inorganic adhesive.

[0034] Preferably, the organic adhesive includes any one or a combination of at least two of epoxy resin, silicone resin or phenolic resin. Among them, typical but non-limiting combinations include the combination of epoxy resin and silicone resin, the combination of phenolic resin and epoxy resin, or the combination of silicone resin, phenolic resin and epoxy resin.

[0035] Preferably, the inorganic adhesive includes phosphate.

[0036] Preferably, the addition amount of the adhesive is 1 to 5 wt% of the total mass of the powder. For example, it can be 1 wt%, 1.5 wt%, 2 wt%, 3 wt%, 4 wt% or 5 wt%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0037] Preferably, the release agent in step (3) includes any one or a combination of at least two of zinc stearate, barium stearate, aluminum stearate or talcum powder. Among them, typical but non-limiting combinations include the combination of zinc stearate and barium stearate, the combination of aluminum stearate and talcum powder, the combination of barium stearate and aluminum stearate, or the combination of talcum powder, zinc stearate and barium stearate.

[0038] Preferably, the addition amount of the release agent is 0.3 to 3 wt% of the total mass of the sheet-like powder after granulation. For example, it can be 0.3 wt%, 0.5 wt%, 1 wt%, 2 wt% or 3 wt%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0039] Preferably, the addition amount of the release agent is 0.3 to 3 wt% of the total mass of the spherical powder after granulation. For example, it can be 0.3 wt%, 0.5 wt%, 1 wt%, 2 wt% or 3 wt%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0040] Preferably, the mass ratio of the sheet-like powder - spherical powder - sheet-like powder filled into the mold cavity in sequence is (0.5 to 1.5):(5 to 9):(0.5 to 3). For example, it can be 0.5:5:0.5, 1:6:3, 1:8:1, 1:7:2, or 1.5:9:3, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0041] Preferably, the pressure of the pressing is 12-20 T / cm 2 , for example, it can be 12 T / cm 2 , 15 T / cm 2 , 16 T / cm 2 , 18 T / cm 2 , 19 T / cm 2 or 20 T / cm 2 etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0042] Preferably, in the second annealing treatment in step (4), the temperature is raised to 550-700 °C at a heating rate of 1.5-3 °C / min in an N2 or H2 atmosphere, and held for 1-3 h. The heating rate is 1.5-3 °C / min, for example, it can be 1.5 °C / min, 1.8 °C / min, 2 °C / min, 2.2 °C / min, 2.5 °C / min or 3 °C / min etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable; the temperature is raised to 550-700 °C, for example, it can be 550 °C, 580 °C, 600 °C, 650 °C or 700 °C etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable; the holding time is 1-3 h, for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 2.8 h or 3 h etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0043] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0044] (1) 5-20 parts of flaky iron-based alloy powder, 80-95 parts of first spherical iron-based alloy powder and 0.5-5 parts of silane coupling agent are sequentially subjected to wet grinding pretreatment at a rotational frequency of 20-30 Hz for 1-5 h, sieving separation and drying to obtain a first powder with an average particle size D50 of 20-200 μm; the iron-based alloy powder includes any one or at least two combinations of FeSi, FeNi, FeSiAl, FeNiMo, FeSiAlNi, FeSiCr or FeSiAlTi; the flaky iron-based alloy powder is sieved through a 50-150 mesh sieve before wet grinding pretreatment; the spherical iron-based alloy powder is sieved through a 300-500 mesh sieve before wet grinding pretreatment; the solvent used in the wet grinding pretreatment includes alcohol and / or acetone;

[0045] (2) After the first powder and the second spherical iron-based alloy powder are independently subjected to the first annealing treatment, passivation treatment and insulation coating treatment in sequence, they are mixed with a binder and subjected to sieving and granulation treatment to obtain granulated flaky powder and granulated spherical powder respectively;

[0046] The first annealing treatment is carried out under nitrogen protection, heating up to 550 - 700°C at a heating rate of 1 - 5°C / min, holding for 1 - 3 h, and then cooling to room temperature;

[0047] The passivating agent used in the passivation treatment includes any one or a combination of at least two of phosphoric acid, boric acid, hydrogen peroxide or nitric acid; the total mass of the passivating agent is 0.1 - 3 wt% of the total mass of the powder;

[0048] The insulating agent used in the insulating coating treatment includes any one or a combination of at least two of silicate, phosphate, mica powder or kaolin, preferably any one or a combination of at least two of SiO2, CaO or Al2O3; the addition amount of the insulating agent is 0.1 - 5 wt% of the total mass of the powder;

[0049] The binder includes an organic binder or an inorganic binder; the organic binder includes any one or a combination of at least two of epoxy resin, silicone resin or phenolic resin; the inorganic binder includes phosphate; the addition amount of the binder is 1 - 5 wt% of the total mass of the powder;

[0050] (3) After the granulated flaky powder and the granulated spherical powder are each independently mixed with a release agent, they are filled into the mold cavity in the order of flaky powder - spherical powder - flaky powder and pressed into a magnetic core blank; the release agent includes any one or a combination of at least two of zinc stearate, barium stearate, aluminum stearate or talc powder; the addition amount of the release agent is 0.3 - 3 wt% of the total mass of the granulated flaky powder; the addition amount of the release agent is 0.3 - 3 wt% of the total mass of the granulated spherical powder; the mass ratio of the flaky powder - spherical powder - flaky powder filled into the mold cavity in sequence is (0.5 - 1.5):(5 - 9):(0.5 - 3); the pressing pressure is 12 - 20 T / cm 2 ;

[0051] (4) The magnetic core blank is heated up to 550 - 700°C at a heating rate of 1.5 - 3°C / min in an N2 / H2 atmosphere, held for 1 - 3 h for the second annealing treatment, and then an insulating paint is sprayed on its surface to obtain the iron-based composite magnetic powder core.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] The preparation method of an iron-based composite magnetic powder core provided by the present invention has low production cost, simple preparation process, low equipment requirements, and the prepared magnetic powder core has high magnetic permeability and low magnetic loss, and is suitable for large-scale popularization and application. Detailed Embodiments

[0054] To facilitate the understanding of the present invention, the following are examples of the present invention. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0055] The present invention will be further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0056] Example 1

[0057] This example provides a preparation method of an iron-based composite magnetic powder core. The preparation method includes the following steps:

[0058] (1) 5 parts of flaky iron-based alloy powder, 95 parts of first spherical iron-based alloy powder, and 0.5 part of silane coupling agent are successively subjected to wet grinding pretreatment at a rotation frequency of 20 Hz for 2 h, sieving separation, and drying to obtain a first powder; the iron-based alloy powder is FeSiAl; the flaky iron-based alloy powder is sieved through a 50-mesh sieve before wet grinding pretreatment; the first spherical iron-based alloy powder is sieved through a 300-mesh sieve before wet grinding pretreatment; 200 parts of alcohol are used for the wet grinding pretreatment.

[0059] (2) The first powder and the second spherical iron-based alloy powder are each independently successively sieved through 50 meshes, 70 meshes, and 100 meshes, first annealed, passivated, and insulated and coated, and then mixed with an adhesive and sieved through 50 meshes for granulation treatment to obtain granulated flaky powder and granulated spherical powder respectively.

[0060] The first annealing treatment is carried out under nitrogen protection, heating to 600 °C at a heating rate of 3 °C / min, holding for 50 min, and cooling to room temperature.

[0061] The passivation treatment uses phosphoric acid with a concentration of 10% accounting for 1 wt% of the total mass of the powder.

[0062] The insulation coating treatment uses kaolin accounting for 0.6 wt% of the total mass of the powder.

[0063] The adhesive is epoxy resin accounting for 2.5 wt% of the total mass of the powder.

[0064] (3) After the granulated flaky powder and the granulated spherical powder are each independently mixed with a release agent, they are sequentially placed into the mold cavity in the order of flaky powder - spherical powder - flaky powder, and the mass ratio of flaky powder - spherical powder - flaky powder is 0.5:9:0.5, and pressed into a magnetic core blank; the release agent is zinc stearate accounting for 0.3 wt% of the total mass of the granulated powder; the pressing pressure is 12.5 T / cm 2 ;

[0065] (4) The magnetic core blank is heated to 600 °C at a heating rate of 2.2 °C / min in a nitrogen atmosphere, held for 1 h, and an insulating paint is sprayed on its surface to obtain the iron-based composite magnetic powder core.

[0066] Example 2

[0067] This example provides a preparation method of an iron-based composite magnetic powder core. The preparation method includes the following steps:

[0068] (1) 10 parts of flaky iron-based alloy powder, 90 parts of first spherical iron-based alloy powder, and 1 part of silane coupling agent are successively subjected to wet grinding pretreatment at a rotational frequency of 25 Hz for 2 h, sieving separation, and drying to obtain the first powder; the iron-based alloy powder is FeSiAl; the flaky iron-based alloy powder is sieved through a 50-mesh sieve before wet grinding pretreatment; the first spherical iron-based alloy powder is sieved through a 350-mesh sieve before wet grinding pretreatment; 200 parts of alcohol is used for the wet grinding pretreatment;

[0069] (2) The first powder and the second spherical iron-based alloy powder are each independently successively sieved through 50 meshes, 70 meshes, and 100 meshes, subjected to first annealing treatment, passivation treatment, and insulation coating treatment, and then mixed with an adhesive, and subjected to sieving and granulation treatment to respectively obtain granulated flaky powder and granulated spherical powder;

[0070] The first annealing treatment is carried out under nitrogen protection at a heating rate of 3 °C / min to 550 °C, held for 1.5 h, and cooled to room temperature;

[0071] The passivation treatment uses phosphoric acid with a concentration of 10% accounting for 0.8 wt% of the total mass of the mixed powder;

[0072] The insulation coating treatment uses kaolin accounting for 0.6 wt% of the total mass of the mixed powder;

[0073] The adhesive is epoxy resin accounting for 4 wt% of the total mass of the mixed powder;

[0074] (3) After the granulated flaky powder and the granulated spherical powder are each independently mixed with a release agent, they are successively placed into the mold cavity in the order of flaky powder - spherical powder - flaky powder. The mass ratio of flaky powder - spherical powder - flaky powder is 1:8:1, and pressed into a magnetic core blank; the release agent is zinc stearate accounting for 0.3 wt% of the total mass of the granulated powder; the pressing pressure is 12 T / cm 2 ;

[0075] (4) The magnetic core blank is heated to 650 °C at a heating rate of 2.2 °C / min in a nitrogen atmosphere, held for 1.5 h, and an insulating paint is sprayed on its surface to obtain the iron-based composite magnetic powder core.

[0076] Example 3

[0077] This embodiment provides a preparation method of an iron-based composite magnetic powder core. The preparation method includes the following steps:

[0078] (1) 20 parts of flaky iron-based alloy powder, 80 parts of first spherical iron-based alloy powder, and 2 parts of silane coupling agent are successively subjected to wet milling pretreatment at a rotational speed frequency of 25 Hz for 2 h, sieving separation, and drying to obtain a first powder. The iron-based alloy powder is FeSiAl. The flaky iron-based alloy powder is sieved through a 150-mesh sieve before wet milling pretreatment. The first spherical iron-based alloy powder is sieved through a 300-mesh sieve before wet milling pretreatment. 200 parts of alcohol is used for the wet milling pretreatment.

[0079] (2) The first powder and the second spherical iron-based alloy powder are each independently successively sieved through 50-mesh, 70-mesh, and 100-mesh sieves, subjected to first annealing treatment, passivation treatment, and insulation coating treatment, and then mixed with an adhesive, and subjected to sieving and granulation treatment to respectively obtain granulated flaky powder and granulated spherical powder.

[0080] The first annealing treatment is carried out under nitrogen protection, heating to 600 °C at a heating rate of 3 °C / min, holding for 2 h, and cooling to room temperature.

[0081] The passivation treatment uses phosphoric acid with a concentration of 10% accounting for 0.6 wt% of the total mass of the mixed powder.

[0082] The insulation coating treatment uses kaolin accounting for 0.5 wt% of the total mass of the mixed powder.

[0083] The adhesive is epoxy resin accounting for 3.5 wt% of the total mass of the mixed powder.

[0084] (3) After the granulated flaky powder and the granulated spherical powder are each independently mixed with a release agent, they are successively placed into the mold cavity in the order of flaky powder - spherical powder - flaky powder. The mass ratio of flaky powder - spherical powder - flaky powder is 1.5:7:1.5, and a magnetic core blank is pressed. The release agent is zinc stearate accounting for 0.3 wt% of the total mass of the granulated powder. The pressing pressure is 14 T / cm 2 ;

[0085] (4) The magnetic core blank is heated to 650 °C at a heating rate of 2.2 °C / min in a nitrogen atmosphere, held for 1.5 h, and an insulating paint is sprayed on its surface to obtain the iron-based composite magnetic powder core.

[0086] Example 4

[0087] This embodiment provides a preparation method of an iron-based composite magnetic powder core. The preparation method includes the following steps:

[0088] (1) 20 parts of flaky iron-based alloy powder, 80 parts of first spherical iron-based alloy powder, and 3 parts of silane coupling agent are successively subjected to wet grinding pretreatment at a rotational frequency of 28 Hz for 1 h, sieving separation, and drying to obtain the first powder; the iron-based alloy powder is FeSiAl; the flaky iron-based alloy powder is sieved through a 150-mesh sieve before wet grinding pretreatment; the first spherical iron-based alloy powder is sieved through a 400-mesh sieve before wet grinding pretreatment; 200 parts of alcohol is used for the wet grinding pretreatment;

[0089] (2) The first powder and the second spherical iron-based alloy powder are each independently successively sieved through 50-mesh, 70-mesh, and 100-mesh, subjected to first annealing treatment, passivation treatment, and insulation coating treatment, and then mixed with an adhesive, followed by sieving granulation treatment to obtain granulated flaky powder and granulated spherical powder respectively;

[0090] The first annealing treatment is carried out under nitrogen protection with a heating rate of 2.5 °C / min to 550 °C, holding for 2 h, and then cooling to room temperature;

[0091] The passivation treatment uses phosphoric acid with a concentration of 10% at 0.5 wt% of the total mass of the mixed powder;

[0092] The insulation coating treatment uses kaolin at 0.4 wt% of the total mass of the mixed powder;

[0093] The adhesive is epoxy resin at 3 wt% of the total mass of the mixed powder;

[0094] (3) After the granulated flaky powder and the granulated spherical powder are each independently mixed with a release agent, they are successively placed into the mold cavity in the order of flaky powder - spherical powder - flaky powder, and the mass ratio of flaky powder - spherical powder - flaky powder is 2:6:2, and pressed into a magnetic core blank; the release agent is zinc stearate at 0.15 wt% of the total mass of the granulated powder; the pressing pressure is 13.5 T / cm 2 ;

[0095] (4) The magnetic core blank is heated to 650 °C at a heating rate of 2.2 °C / min in a nitrogen atmosphere, held for 2 h, and an insulating paint is sprayed on its surface to obtain the iron-based composite magnetic powder core.

[0096] Example 5

[0097] This example provides a preparation method of an iron-based composite magnetic powder core, and the preparation method includes the following steps:

[0098] (1) 20 parts of flaky iron-based alloy powder, 80 parts of first spherical iron-based alloy powder, and 5 parts of silane coupling agent are successively subjected to wet grinding pretreatment at a rotational frequency of 28 Hz for 1 h, sieving separation, and drying to obtain the first powder; the iron-based alloy powder is FeSiAl; the flaky iron-based alloy powder is sieved through a 50-mesh sieve before wet grinding pretreatment; the first spherical iron-based alloy powder is sieved through a 350-mesh sieve before wet grinding pretreatment; 200 parts of alcohol is used for the wet grinding pretreatment;

[0099] (2) The first powder and the second spherical iron-based alloy powder are each independently successively sieved through 50 mesh, 70 mesh, and 100 mesh, subjected to first annealing treatment, passivation treatment, and insulation coating treatment, and then mixed with an adhesive and subjected to sieving granulation treatment to respectively obtain granulated flaky powder and granulated spherical powder;

[0100] The first annealing treatment is carried out under nitrogen protection, heating to 650 °C at a heating rate of 2.5 °C / min, holding for 2 h, and cooling to room temperature;

[0101] The passivation treatment uses phosphoric acid with a concentration of 10% at 0.3 wt% of the total mass of the mixed powder;

[0102] The insulation coating treatment uses kaolin at 0.35 wt% of the total mass of the mixed powder;

[0103] The adhesive is silicone resin at 5 wt% of the total mass of the mixed powder;

[0104] (3) After the granulated flaky powder and the granulated spherical powder are each independently mixed with a release agent, they are successively placed into the mold cavity in the order of flaky powder - spherical powder - flaky powder, and the mass ratio of flaky powder - spherical powder - flaky powder is 2:5:3, and pressed into a magnetic core blank; the release agent is zinc stearate at 0.3 wt% of the total mass of the granulated powder; the pressing pressure is 13.5 T / cm 2 ;

[0105] (4) The magnetic core blank is heated to 700 °C at a heating rate of 2.2 °C / min in a nitrogen atmosphere, held for 2 h, and an insulating paint is sprayed on its surface to obtain the iron-based composite magnetic powder core.

[0106] Comparative Example 1

[0107] This comparative example provides a preparation method of an iron-based composite magnetic powder core, and the preparation method includes the following steps:

[0108] (1) 100 parts of spherical iron-based alloy powder and 3 parts of silane coupling agent are successively mixed by mechanical stirring for 1 h and then dried to obtain the first powder; the iron-based alloy powder is FeSiAl; the spherical iron-based alloy powder is sieved through a 300-mesh sieve before wet grinding pretreatment; 200 parts of alcohol are used for the wet grinding pretreatment;

[0109] (2) After the first powder is successively subjected to the first annealing treatment, passivation treatment and insulation coating treatment, it is mixed with an adhesive and then subjected to screening and granulation treatment to obtain the granulated powder;

[0110] The first annealing treatment is carried out under nitrogen protection, heating up to 650 °C at a heating rate of 2.5 °C / min, holding for 2 h, and then cooling to room temperature;

[0111] The passivation treatment uses phosphoric acid with a concentration of 10% accounting for 1.5 wt% of the total mass of the mixed powder;

[0112] The insulation coating treatment uses kaolin accounting for 0.35 wt% of the total mass of the mixed powder;

[0113] The adhesive is silicone resin accounting for 5 wt% of the total mass of the mixed powder;

[0114] (3) After the granulated powder is mixed with a release agent, it is pressed into a magnetic core blank; the release agent is zinc stearate accounting for 0.3 wt% of the total mass of the granulated powder; the pressing pressure is 13 T / cm 2 ;

[0115] (4) The magnetic core blank is heated up to 700 °C at a heating rate of 2.2 °C / min in a nitrogen atmosphere, held for 2 h, and an insulating paint is sprayed on its surface to obtain the iron-based composite magnetic powder core.

[0116] The magnetic permeability of the iron-based composite magnetic powder cores obtained from the above examples and comparative examples under the condition of 50 kHz and the magnetic loss results at 50 kHz and 100 mT are shown in Table 1.

[0117] Table 1

[0118] Magnetic permeability <![CDATA[Loss (W / cm 3 )]]> Example 1 118 89 Example 2 120 91 Example 3 122 93 Example 4 143 92 Example 5 151 93 Comparative Example 1 115 95

[0119] In summary, the preparation method of the iron-based composite magnetic powder core provided by the present invention has a higher magnetic permeability and relatively lower magnetic loss by wet grinding and pretreating the flaky iron-based alloy powder, spherical iron-based alloy powder and silane coupling agent. The comprehensive performance is good, and it has the prospect of large-scale popularization and application.

[0120] The applicant declares that the above description is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A preparation method of an iron-based composite magnetic powder core, characterized in that, The preparation method includes the following steps: (1) The flaky iron-based alloy powder, the first spherical iron-based alloy powder, and the silane coupling agent are successively subjected to wet grinding pretreatment, sieving separation, and drying to obtain the first powder; The iron-based alloy powder includes any one or a combination of at least two of FeSi, FeNi, FeSiAl, FeNiMo, FeSiAlNi, FeSiCr, or FeSiAlTi; The flaky iron-based alloy powder is sieved through a 50-150 mesh sieve before wet grinding pretreatment; The first spherical iron-based alloy powder is sieved through a 300-500 mesh sieve before wet grinding pretreatment; The mass parts of the flaky iron-based alloy powder, the first spherical iron-based alloy powder, and the silane coupling agent are 5-20 parts, 80-95 parts, and 0.5-5 parts respectively; (2) After the first powder and the second spherical iron-based alloy powder are independently subjected to the first annealing treatment, passivation treatment, and insulation coating treatment in sequence, they are mixed with the binder, and after sieving and granulation treatment, the granulated flaky powder and the granulated spherical powder are obtained respectively; (3) After the granulated flaky powder and the granulated spherical powder are independently mixed with the release agent, they are filled into the mold cavity in the order of flaky powder - spherical powder - flaky powder and pressed into a magnetic core blank; The release agent includes any one or a combination of at least two of zinc stearate, barium stearate, aluminum stearate, or talcum powder; The addition amount of the release agent is 0.3-3 wt% of the total mass of the granulated flaky powder; The addition amount of the release agent is 0.3-3 wt% of the total mass of the granulated spherical powder; The mass ratio of the flaky powder - spherical powder - flaky powder filled into the mold cavity in sequence is (0.5-1.5):(5-9):(0.5-3); The pressure of the pressing is 12 - 20 T / cm 2 ; (4) After the magnetic core blank is subjected to the second annealing treatment, an insulating paint is sprayed on its surface to obtain the iron-based composite magnetic powder core.

2. The preparation method according to claim 1, characterized in that, The solvent used in the wet grinding pretreatment in step (1) includes alcohol and / or acetone.

3. The preparation method according to claim 1, characterized in that, The time of the wet grinding pretreatment is 1-5 h.

4. The preparation method according to claim 1, characterized in that, The rotational speed frequency of the wet grinding pretreatment is 20-30 Hz.

5. The preparation method according to claim 1, characterized in that, The average particle size D50 of the first powder is 20-200 μm.

6. The preparation method according to claim 1, characterized in that, In the first annealing treatment in step (2), the temperature is raised to 550-700 °C at a heating rate of 1-5 °C / min under nitrogen protection, held for 1-3 h, and then cooled to room temperature.

7. The preparation method according to claim 1, characterized in that, The passivating agent used in the passivation treatment in step (2) includes any one or a combination of at least two of phosphoric acid, boric acid, hydrogen peroxide, or nitric acid; 8. The preparation method according to claim 7, characterized in that, The total mass of the passivating agent is 0.1-3 wt% of the total mass of the powder; 9. The preparation method according to claim 1, characterized in that, The insulating agent used in the insulation coating treatment includes any one or a combination of at least two of silicate, phosphate, mica powder, or kaolin; 10. The preparation method according to claim 9, characterized in that, The insulating agent used in the insulation coating treatment is any one or a combination of at least two of SiO2, CaO, or Al2O3; 11. The preparation method according to claim 9, characterized in that, The addition amount of the insulating agent is 0.1-5 wt% of the total mass of the powder; 12. The preparation method according to claim 1, characterized in that, After the insulation coating treatment in step (2), drying is carried out.

13. The preparation method according to claim 12, characterized in that, The drying temperature is 70-140 °C.

14. The preparation method according to claim 1, wherein The binder in step (2) includes an organic binder or an inorganic binder.

15. The preparation method according to claim 14, wherein The organic binder includes any one or a combination of at least two of epoxy resin, silicone resin or phenolic resin.

16. The preparation method according to claim 14, wherein The inorganic binder includes phosphate.

17. The preparation method according to claim 1, wherein The addition amount of the binder is 1-5 wt% of the total mass of the powder.

18. The preparation method according to claim 1, wherein In step (4), the second annealing treatment is carried out in an N2 or H2 atmosphere, heating up to 550-700 °C at a heating rate of 1.5-3 °C / min, and holding for 1-3 h.