Rare earth soft magnetic powder and preparation method thereof, soft magnetic composite material and preparation method thereof

Abstract

The present invention provides a rare earth soft magnetic powder and a preparation method thereof, a soft magnetic composite material and a preparation method thereof, wherein the rare earth soft magnetic powder comprises Ce2Fe 17‑x‑y Ni x T y N z , wherein T includes any one of Si, C or B or a combination of at least two; x, y, and z are the atomic contents of Ni, T, and N, respectively, with x ranging from 0.1 to 0.5, y ranging from 0.1 to 0.5, and z ranging from 2 to 4; the rare earth soft magnetic powder is mixed with a binder to prepare a soft magnetic composite material, which can meet the use of electronic devices under high-frequency working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic materials, in particular to rare earth soft magnetic powder and a preparation method thereof, and a soft magnetic composite material and a preparation method thereof. Background Art

[0002] In recent years, with the development of mobile communication equipment (computers, mobile phones, digital cameras, car navigation, etc.) towards miniaturization, multifunctionality, high-speed processing and high-frequency driving, the industry has an increasingly urgent demand for soft magnetic materials that can exhibit low-loss characteristics in high-frequency and ultra-high-frequency electromagnetic field changes.

[0003] Common soft magnetic materials currently on the market include ferrite soft magnetic materials (manganese zinc, nickel zinc), metal soft magnetic materials (Fe, Fe-Si, Fe-Si-Al, Fe-Si-Cr, Fe-Ni, etc.) and amorphous nanocrystalline soft magnetic materials. Among them, ferrite soft magnetic materials have low eddy current losses under high-frequency working conditions due to their high resistivity, so they can operate at a frequency of 1MHz. However, the saturation magnetization intensity of ferrite soft magnetic materials is low (<0.5T), which is not suitable for the preparation of very small magnetic components. Compared with ferrite soft magnetic materials, the saturation magnetization intensity of metal soft magnetic materials is very high, which is suitable for the miniaturization of magnetic devices. However, the resistivity of metal soft magnetics is relatively low, and very large eddy current losses will be generated under high-frequency working conditions, which will not only greatly reduce energy utilization efficiency, but also cause the magnetic device to heat up violently and reduce its service life. Therefore, its operation generally does not exceed 100kHz. The saturation magnetization intensity of amorphous nanocrystalline soft magnetic materials is higher than that of ferrite soft magnetic materials. At the same time, they have higher resistivity and small grain size. Therefore, even under high-frequency working conditions, the eddy current loss is relatively small. Therefore, they can work at higher electromagnetic field frequencies. For example, nano soft magnetic powder particles with good insulation coating can even work at a frequency of 100MHz.

[0004] In recent years, researchers have discovered that the cutoff frequency of ferrite-type rare earth-iron-nitrogen compounds (such as Ce-Fe-N and Nd-Fe-N) is very high, reaching 6 GHz, exceeding the cutoff frequency of microwave ferrite. However, the resistance of these materials is much lower than that of ferrite, and the eddy current losses under high-frequency operating conditions are very large, making it difficult to fully utilize their high-frequency characteristics.

[0005] CN114974786A discloses a soft magnetic composite material comprising a first soft magnetic metal powder, a first insulating coating material, and airflow-broken granulated powder. The airflow-broken granulated powder comprises a second soft magnetic metal powder and a second insulating coating material, and the second insulating coating material is fully solidified. The first insulating coating material and / or the second insulating coating material in the soft magnetic composite material are uniformly dispersed. The soft magnetic composite material is used to prepare metal powder cores and molded inductors. The resulting molded inductors exhibit high insulation resistance and initial magnetic permeability.

[0006] CN114023522A discloses a micron-sized magnetic composite material with good stability. The magnetic material comprises metal compound magnetic particles and micro-nano magnetic composite particles. The micro-nano magnetic composite particles are iron particles containing silicon dioxide particles with an average powder particle size of 10 nm. The metal compound magnetic particles include Fe-Si-based soft magnetic alloy particles, Fe-Aluminum-based soft magnetic alloy particles, Fe-Si-Aluminum-based soft magnetic alloy particles, Fe-Cr-based soft magnetic alloy particles, Ni-based soft magnetic alloy particles, and a two-dimensional magnetic moment micropowder. The micron-sized composite magnetic material prepared by the method has the advantages of high doping concentration of magnetic particles, simple preparation process, and high stability. Furthermore, due to the coating effect of the polymer organic compound, the prepared magnetic polymer micro-nano composite particles also have good biocompatibility.

[0007] CN113724958A discloses a method for producing an iron-based soft magnetic core based on alloying reduced iron powder, belonging to the field of soft magnetic materials and powder metallurgy. The method comprises: (1) hydrogen reduction of high-purity reduced iron powder; (2) alloying the high-purity reduced iron powder with alloy powder and a binder to obtain an iron-based soft magnetic powder; (3) performing a surface inorganic insulation coating treatment; (4) adding the coated iron-based soft magnetic powder to an acetone resin solution, heating and stirring, and then mixing with a release agent and pressing to obtain an iron-based soft magnetic composite block; (5) heat-treating the iron-based soft magnetic composite block to obtain an iron-based soft magnetic core. The method is simple in process and low in cost, can effectively reduce the burnout of alloy components during the smelting process, basically eliminate defects such as satellite powder and surface pits, and avoid the situation where component segregation is easy to occur during the solidification process.

[0008] However, these soft magnetic materials suffer from high losses in high-frequency or ultra-high-frequency electromagnetic fields, limiting their widespread application. Therefore, developing a rare earth soft magnetic powder and its preparation method, as well as a soft magnetic composite material and its preparation method, that can meet the requirements of electronic devices operating under GHz conditions is of great significance. Summary of the Invention

[0009] To solve the above technical problems, the present invention provides a rare earth soft magnetic powder and a preparation method thereof, a soft magnetic composite material and a preparation method thereof. After mixing various raw material powders, they are subjected to heat treatment, vacuum heating treatment, melting treatment and rapid cooling treatment, and the temperature of the melting treatment is strictly controlled to obtain a glassy mixture; the glassy mixture is heated in a nitrogen atmosphere to undergo crystallization and nitridation reactions, and finally a rare earth soft magnetic powder is obtained; the soft magnetic composite material is prepared by mixing the rare earth soft magnetic powder with a binder, and has low high-frequency eddy current loss, which can meet the needs of electronic devices under high-frequency working conditions.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a rare earth soft magnetic powder, wherein the rare earth soft magnetic powder comprises Ce2Fe 17-x- y Ni x T y N z , wherein T includes any one of Si, C or B or a combination of at least two; x, y, and z are the atomic contents of Ni, T, and N, respectively, with x being 0.1 to 0.5, y being 0.1 to 0.5, and z being 2 to 4.

[0012] The rare earth soft magnetic powder of the present invention includes Ce2Fe 17-x-y Ni x T y N z , has an easy-face structure, in which Ce is composed of Ce2Fe 17-x-y Ni x T y N z The key substance of the compound, adding ferromagnetic element Ni in appropriate amount can improve the soft magnetic properties of the material, such as magnetic permeability. T includes any one of Si, C or B or a combination of at least two. By adding appropriate amounts of the above substances, the eddy current loss of the material at high frequency can be reduced, but excessive addition will reduce the soft magnetic properties of the material. The elements are combined in a specific atomic ratio and work synergistically to form a soft magnetic composite material made of rare earth soft magnetic powder. It can be used in high-frequency environments above 1GHz and has low eddy current loss.

[0013] In the present invention, x is 0.1 to 0.5, for example, it can be 0.1, 0.2, 0.3, 0.4 or 0.5, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable; y is 0.1 to 0.5, for example, it can be 0.1, 0.2, 0.3, 0.4 or 0.5, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable; z is 2 to 4, for example, it can be 2, 2.5, 3, 3.5, 3.8 or 4, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0014] Preferably, the rare earth soft magnetic powder is in a flake shape.

[0015] Preferably, the average particle size of the rare earth soft magnetic powder is 50 to 100 nm, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0016] In a second aspect, the present invention further provides a method for preparing the rare earth soft magnetic powder as described in the first aspect, the preparation method comprising the following steps:

[0017] (1) Raw materials Fe2O3 powder, Ce2O3 powder, Ni2O3 powder, SiO2 powder, C powder and B2O3 powder, according to Ce2Fe 17-x-y Ni x T y N z , mixing to obtain a mixed powder;

[0018] (2) After the mixed powder is heat-treated in a hydrogen atmosphere, it is mixed with a reducing agent and an auxiliary agent, and subjected to vacuum heating treatment to obtain an intermediate product with a loose texture;

[0019] (3) The intermediate product is subjected to a smelting treatment and a rapid cooling treatment in sequence, and then heated in a nitrogen atmosphere to undergo crystallization and nitridation reactions to obtain a reacted substance; the heating temperature is 400-550° C.;

[0020] (4) mixing the reacted substance with an acetic acid solution, stirring and solid-liquid separation in sequence to obtain the rare earth soft magnetic powder.

[0021] The preparation method of the rare earth soft magnetic powder described in the present invention is to heat-treat the mixed powder in a hydrogen atmosphere in order to reduce the Fe2O3 in the mixed powder to obtain ultrafine metal Fe powder; then the high activity of the reducing agent is used to reduce Ce2O3 to obtain rare earth metal Ce; an auxiliary agent is used to reduce the melting temperature of the raw material mixture involved in the vacuum heating treatment to obtain a loose intermediate product; then the intermediate product is sequentially subjected to smelting treatment and rapid cooling treatment to form a glassy mixture; the glassy mixture is heated in a nitrogen atmosphere to undergo crystallization and nitridation reaction to obtain a reacted substance; finally, an acetic acid solution is used to dissolve the non-magnetic substance in the reacted substance into the solution to finally obtain rare earth soft magnetic powder. In the present invention, the temperature at which the glassy mixture is heated in a nitrogen atmosphere is 400-550°C. When the heating temperature is too high, the reacted substance will not form a phase composition of Ce2Fe 17-x-y Ni x T y N z When the heating temperature is low, the nitrogen content of the resulting rare earth soft magnetic powder is low and the magnetic loss is significantly increased.

[0022] The heating temperature of the present invention is 400-550°C, for example, it can be 400°C, 420°C, 450°C, 500°C, 530°C or 550°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the temperature of the heat treatment in step (2) is 700°C.

[0024] Preferably, the heat treatment time is 10 hours.

[0025] Preferably, the purity of hydrogen in the hydrogen atmosphere is greater than 99.9%, for example, it may be 99.9%, 99.91%, 99.93%, 99.95%, 99.97% or 99.99%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the reducing agent comprises metallic calcium.

[0027] Preferably, the auxiliary agent includes B2O3 powder.

[0028] In the present invention, the auxiliary agent preferably includes B2O3 powder, which mainly reduces the melting temperature of the raw material mixture involved in the vacuum heating treatment. The addition of the B2O3 powder will not affect the final Ce2Fe 17-x-y Ni x T y N z The composition of Ce2Fe 17-x-yNi x T y N z T is any one of Si, C or B or a combination of at least two of them, and is determined by the initial raw material SiO2 powder, C powder or B2O3 powder.

[0029] Preferably, the amount of the reducing agent added accounts for 15% of the mass of the mixed powder.

[0030] Preferably, the amount of the additive added accounts for 3% of the mass of the mixed powder.

[0031] Preferably, the vacuum degree of the vacuum heating treatment in step (2) is 10 -2 Pa.

[0032] Preferably, the heating step of the vacuum heat treatment includes: first heating to 800°C, and then filling with argon gas and heating to 1000°C.

[0033] Preferably, the holding time of the vacuum heating treatment is 4 hours.

[0034] Preferably, the vacuum heating treatment is followed by cooling to 20-30°C, for example, 20°C, 23°C, 25°C, 27°C, 29°C or 30°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] Preferably, the temperature of the smelting treatment in step (3) is 1300-1500°C, for example, it can be 1300°C, 1350°C, 1400°C, 1450°C, 1470°C or 1500°C, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0036] The present invention preferably uses a smelting temperature of 1300-1500°C. The loose intermediate product undergoes smelting and rapid cooling to form a glassy mixture. Lower smelting temperatures can slow the diffusion of elements within the material, leading to uneven distribution of components within the alloy and a reduction in the proportion of soft magnetic phases. While the resulting soft magnetic composite material made from the rare earth soft magnetic powder exhibits lower magnetic losses, its magnetic permeability is significantly reduced. Higher smelting temperatures increase energy consumption and the production cost of the rare earth soft magnetic powder.

[0037] Preferably, the rapid cooling treatment is achieved by the following method: the molten liquid after the smelting treatment flows through a quartz nozzle onto a high-speed rotating molybdenum roller to be rapidly cooled to form a glassy mixture.

[0038] Preferably, the rotational speed of the molybdenum roller is 20-25 m / s, for example, it can be 30 m / s, 21 m / s, 22 m / s, 23 m / s, 24 m / s or 25 m / s, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0039] Preferably, the heating time is 6 to 10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] In the present invention, the operation step of mixing the reacted substance with the acetic acid solution in step (4) can be to first immerse the reacted substance in deionized water, then add the acetic acid solution, and continuously stir to dissolve the non-magnetic substance in the reacted substance into the water. The present invention does not need to clearly define the concentration of the acetic acid solution, as long as the non-magnetic impurities such as CaO in the reactant are completely dissolved, and then perform solid-liquid separation. Step (4) is repeated until the content of Ca ions in the reactant is less than 0.1%.

[0041] Preferably, the solid-liquid separation comprises filtration.

[0042] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0043] (1) Raw materials Fe2O3 powder, Ce2O3 powder, Ni2O3 powder, SiO2 powder, C powder and B2O3 powder, according to Ce2Fe 17-x-y Ni x T y N z , mixing to obtain a mixed powder;

[0044] (2) The mixed powder is heat treated at 700°C for 10 hours in a hydrogen atmosphere with a purity of >99.9%, and then mixed with a reducing agent and an auxiliary agent, and vacuumed to 10 -2 Pa was heated in vacuum for 4 h to obtain an intermediate product with loose texture;

[0045] The reducing agent includes metallic calcium; the auxiliary agent includes B2O3 powder; the amount of the reducing agent added accounts for 15% of the mass of the mixed powder; the amount of the auxiliary agent added accounts for 3% of the mass of the mixed powder; the heating step of the vacuum heating treatment includes: first heating to 800°C, then filling with argon gas and heating to 1000°C; cooling to 20-30°C after the vacuum heating treatment;

[0046] (3) The intermediate product is subjected to a melting treatment at a temperature of 1300-1500° C. and a rapid cooling treatment, and then heated at a temperature of 400-550° C. for 6-10 hours in a nitrogen atmosphere to undergo crystallization and nitridation reactions to obtain a reacted substance;

[0047] The rapid cooling process is achieved by the following method: the molten liquid after the smelting process flows through a quartz nozzle onto a high-speed rotating molybdenum roller with a rotation speed of 20 to 25 m / s, so as to rapidly cool it to form a glassy mixture;

[0048] (4) mixing the reacted substance with an acetic acid solution, stirring and solid-liquid separation in sequence to obtain the rare earth soft magnetic powder.

[0049] In the third aspect, the present invention also provides a soft magnetic composite material, which is prepared by mixing the rare earth soft magnetic powder described in the first aspect with a binder; the rare earth soft magnetic powder accounts for 20% to 70% of the mass of the soft magnetic composite material, for example, it can be 20%, 30%, 40%, 50%, 60% or 70%, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0050] The soft magnetic composite material described in the present invention is prepared by mixing the rare earth soft magnetic powder described in the first aspect with a binder; the binder may include a thermosetting binder such as epoxy resin, or a thermoplastic binder such as nylon 6, nylon 12, or polyphenylene sulfide. The rare earth soft magnetic powder in the soft magnetic composite material of the present invention accounts for 20% to 70% of its mass. When the rare earth soft magnetic powder accounts for less than 20%, the magnetic permeability of the soft magnetic composite material is low, which is not conducive to the miniaturization of magnetic devices. When the rare earth soft magnetic powder accounts for more than 70%, the loss of the soft magnetic composite material at high frequencies is significantly increased.

[0051] In a fourth aspect, the present invention further provides a method for preparing the soft magnetic composite material as described in the third aspect, the preparation method comprising the following steps:

[0052] (a) mixing epoxy resin and acetone to obtain a mixed solution;

[0053] (b) mixing the mixed solution with rare earth soft magnetic powder and stirring to obtain rare earth soft magnetic powder coated with epoxy resin;

[0054] (c) The rare earth soft magnetic powder coated with epoxy resin is dried, mixed with a thermoplastic binder, kneaded and granulated to obtain the soft magnetic composite material.

[0055] The preparation method of the soft magnetic composite material described in the present invention first mixes rare earth soft magnetic powder with a mixed solution containing epoxy resin, and coats a layer of polymer resin on the surface of the rare earth soft magnetic powder to form a protective layer. In this way, the rare earth soft magnetic powder is not easily oxidized during the subsequent mixing and granulation process.

[0056] Preferably, the amount of epoxy resin added in step (a) accounts for 3% of the mass of the rare earth soft magnetic powder.

[0057] Preferably, the volume ratio of the mixed solution to the rare earth soft magnetic powder is 1.5:1 to 2:1, for example, it can be 1.5:1, 1.6:1, 1.7:1, 1.8:1 or 2:1, etc., but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable.

[0058] Preferably, the temperature of the drying treatment in step (c) is 70°C.

[0059] Preferably, the drying time is 1 hour.

[0060] Preferably, the thermoplastic binder includes any one of nylon 6, nylon 12 or polyphenylene sulfide, or a combination of at least two of them, wherein typical but non-limiting combinations include a combination of nylon 6 and nylon 12, a combination of polyphenylene sulfide and nylon 6, or a combination of nylon 12, polyphenylene sulfide and nylon 6.

[0061] Preferably, the added amount of the thermoplastic binder accounts for 17 to 67% of the mass of the rare earth soft magnetic powder coated with epoxy resin, for example, it can be 17%, 20%, 30%, 50%, 60% or 67%, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0062] Preferably, the mixing temperature is 5 to 10°C higher than the softening temperature of the thermoplastic binder, for example, 5°C, 6°C, 7°C, 8°C, 9°C or 10°C, etc., but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0063] Preferably, argon gas is introduced during the mixing process for protection.

[0064] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0065] (a) mixing epoxy resin and acetone to obtain a mixed solution; mixing and stirring the mixed solution with rare earth soft magnetic powder to obtain rare earth soft magnetic powder coated with epoxy resin;

[0066] The amount of the epoxy resin added is 3% of the mass of the rare earth soft magnetic powder; the volume ratio of the mixed solution to the rare earth soft magnetic powder is 1.5:1 to 2:1;

[0067] (b) drying the rare earth soft magnetic powder coated with epoxy resin at 70° C. for 1 hour, mixing with a thermoplastic binder, kneading and granulating to obtain the soft magnetic composite material;

[0068] The thermoplastic binder includes any one of nylon 6, nylon 12 or polyphenylene sulfide, or a combination of at least two thereof; the amount of the thermoplastic binder added accounts for 17 to 67% of the mass of the rare earth soft magnetic powder coated with epoxy resin; the mixing temperature is 5 to 10°C higher than the softening temperature of the thermoplastic binder; and argon gas is introduced during the mixing process for protection.

[0069] Compared with the prior art, the present invention has at least the following beneficial effects:

[0070] (1) The method for preparing rare earth soft magnetic powder provided by the present invention produces rare earth soft magnetic powder with a relatively fine particle size. The soft magnetic composite material prepared from the rare earth soft magnetic powder can be used in high-frequency environments above 1 GHz and has low eddy current loss.

[0071] (2) The method for preparing the rare earth soft magnetic powder and the method for preparing the soft magnetic composite material provided by the present invention have simple operation procedures, low preparation costs, and have prospects for large-scale promotion and application. DETAILED DESCRIPTION

[0072] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0073] The present invention is further described in detail below. However, the following examples are merely simplified 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.

[0074] Example 1

[0075] This embodiment provides a method for preparing rare earth soft magnetic powder, the preparation method comprising the following steps:

[0076] (1) Raw materials Fe2O3 powder, Ce2O3 powder, Ni2O3 powder, SiO2 powder, according to Ce2Fe 17-x-y Ni x T y N z , and mixed to obtain a mixed powder; wherein x=0.2, y=0.2, and T is Si element;

[0077] (2) The mixed powder is placed in a tube furnace and heat treated at 700°C for 10 hours in a hydrogen atmosphere with a purity of >99.9%, and then mixed with a reducing agent, metal calcium, and an auxiliary agent, B2O3 powder, and vacuumed to 10 -2 Pa was heated in vacuum for 4 h to obtain an intermediate product with loose texture;

[0078] The amount of the reducing agent added is 15% of the mass of the mixed powder; the amount of the auxiliary agent added is 3% of the mass of the mixed powder; the heating step of the vacuum heating treatment includes: first heating to 800°C, then filling with argon gas and heating to 1000°C; cooling to 25°C after the vacuum heating treatment;

[0079] (3) The intermediate product is placed in a melting furnace and subjected to a melting treatment at a temperature of 1300° C. to completely melt the intermediate product. The molten liquid is then flowed through a quartz nozzle onto a molybdenum roller rotating at a high speed of 20 m / s for rapid cooling to form a glassy mixture. The glassy mixture is placed in a nitrogen atmosphere treatment furnace and heated at a temperature of 500° C. for 6 h to cause crystallization and nitridation reactions to occur, thereby obtaining a reacted substance.

[0080] (4) The reacted material is immersed in deionized water, and then an acetic acid solution is added, followed by stirring and filtering to obtain rare earth soft magnetic powder.

[0081] The composition of the rare earth soft magnetic powder obtained in this embodiment is Ce2Fe 16.6 Ni 0.2 Si 0.2 N 2.8 , the average particle size is 80nm.

[0082] This embodiment further provides a soft magnetic composite material, which is prepared by mixing the above-mentioned rare earth soft magnetic powder with a binder. The preparation method includes the following steps:

[0083] (a) mixing epoxy resin and acetone to obtain a mixed solution; mixing and stirring the mixed solution with rare earth soft magnetic powder to obtain rare earth soft magnetic powder coated with epoxy resin;

[0084] The amount of the epoxy resin added is 3% of the mass of the rare earth soft magnetic powder; the volume ratio of the mixed solution to the rare earth soft magnetic powder is 1.5:1;

[0085] (b) drying the epoxy resin-coated rare earth soft magnetic powder at 70° C. for 1 hour, mixing the powder with a thermoplastic binder, nylon 6, and kneading and granulating the mixture in a twin-screw granulator to obtain the soft magnetic composite material;

[0086] The amount of the thermoplastic binder added is 40% of the mass of the rare earth soft magnetic powder coated with epoxy resin; the mixing temperature is 8° C. higher than the softening temperature of the thermoplastic binder; and argon gas is introduced during the mixing process for protection.

[0087] The soft magnetic composite material obtained in this embodiment was made into a ring sample and tested with a vector network analyzer at a frequency of 1 GHz, and the results showed that the magnetic permeability μ' was 4.22 and the magnetic loss tanδμ was 0.11.

[0088] Example 2

[0089] This embodiment provides a method for preparing rare earth soft magnetic powder. The preparation method is the same as that of Example 1 except that x=0.1 and y=0.1 in step (1).

[0090] The composition of the rare earth soft magnetic powder obtained in this embodiment is Ce2Fe 16.8 Ni 0.1 Si 0.1 N 2.8 , the average particle size is 82nm.

[0091] This embodiment also provides a soft magnetic composite material, which is prepared by mixing the above-mentioned rare earth soft magnetic powder with a binder. The preparation method is the same as that of Example 1.

[0092] The soft magnetic composite material obtained in this embodiment was made into a ring sample and tested with a vector network analyzer at a frequency of 1 GHz. The results showed that the magnetic permeability μ' was 4.33 and the magnetic loss tanδμ was 0.13.

[0093] Example 3

[0094] This embodiment provides a method for preparing rare earth soft magnetic powder. The preparation method is the same as that of Example 1 except that x=0.5 and y=0.5 in step (1).

[0095] The composition of the rare earth soft magnetic powder obtained in this embodiment is Ce2Fe 16.0 Ni 0.5 Si 0.5 N 2.8 , the average particle size is 75nm.

[0096] This embodiment also provides a soft magnetic composite material, which is prepared by mixing the above-mentioned rare earth soft magnetic powder with a binder. The preparation method is the same as that of Example 1.

[0097] The soft magnetic composite material obtained in this embodiment was made into a ring sample and tested with a vector network analyzer at a frequency of 1 GHz. The results showed that the magnetic permeability μ' was 3.75 and the magnetic loss tanδμ was 0.10.

[0098] Example 4

[0099] This embodiment provides a method for preparing rare earth soft magnetic powder. The preparation method is the same as that of Example 1 except that the temperature of the smelting treatment in step (3) is 1500°C.

[0100] The composition of the rare earth soft magnetic powder obtained in this embodiment is Ce2Fe 16.6 Ni 0.2 Si 0.2 N 2.7 , the average particle size is 85nm.

[0101] This embodiment also provides a soft magnetic composite material, which is prepared by mixing the above-mentioned rare earth soft magnetic powder with a binder. The preparation method is the same as that of Example 1.

[0102] The soft magnetic composite material obtained in this embodiment was made into a ring sample and tested with a vector network analyzer at a frequency of 1 GHz. The results showed that the magnetic permeability μ' was 4.25 and the magnetic loss tanδμ was 0.13.

[0103] Example 5

[0104] This embodiment provides a method for preparing rare earth soft magnetic powder. The preparation method is the same as that of Example 1 except that the heating temperature in step (3) is 400° C. and the heating time is 10 h.

[0105] The composition of the rare earth soft magnetic powder obtained in this embodiment is Ce2Fe 16.6 Ni 0.2 Si 0.2 N 2.5 , the average particle size is 55nm.

[0106] This embodiment also provides a soft magnetic composite material, which is prepared by mixing the above-mentioned rare earth soft magnetic powder with a binder. The preparation method is the same as that of Example 1.

[0107] The soft magnetic composite material obtained in this embodiment was made into a ring sample and tested with a vector network analyzer at a frequency of 1 GHz. The results showed that the magnetic permeability μ' was 3.83 and the magnetic loss tanδμ was 0.07.

[0108] Example 6

[0109] This embodiment provides a method for preparing rare earth soft magnetic powder. The preparation method is the same as that of Example 1 except that the heating temperature in step (3) is 550° C. and the heating time is 6 h.

[0110] The composition of the rare earth soft magnetic powder obtained in this embodiment is Ce2Fe 16.6 Ni 0.2Si 0.2 N 3.2 , the average particle size is 100nm.

[0111] This embodiment also provides a soft magnetic composite material, which is prepared by mixing the above-mentioned rare earth soft magnetic powder with a binder. The preparation method is the same as that of Example 1.

[0112] The soft magnetic composite material obtained in this embodiment was made into a ring sample and tested with a vector network analyzer at a frequency of 1 GHz. The results showed that the magnetic permeability μ' was 4.83 and the magnetic loss tanδμ was 0.13.

[0113] Example 7

[0114] This embodiment provides a soft magnetic composite material, which is prepared by mixing the rare earth soft magnetic powder described in Example 1 with a binder. The preparation method is the same as that of Example 1, except that the amount of thermoplastic binder nylon 6 added accounts for 17% of the mass of the rare earth soft magnetic powder coated with epoxy resin.

[0115] The soft magnetic composite material obtained in this embodiment was made into a ring sample and tested with a vector network analyzer at a frequency of 1 GHz. The results showed that the magnetic permeability μ' was 6.30 and the magnetic loss tanδμ was 0.21.

[0116] Example 8

[0117] This embodiment provides a soft magnetic composite material, which is prepared by mixing the rare earth soft magnetic powder described in Example 1 with a binder. The preparation method is the same as that of Example 1, except that the amount of thermoplastic binder nylon 6 added accounts for 67% of the mass of the rare earth soft magnetic powder coated with epoxy resin.

[0118] The soft magnetic composite material obtained in this embodiment was made into a ring sample, and tested with a vector network analyzer at a frequency of 1 GHz. The results showed that the magnetic permeability μ' was 2.18, and the magnetic loss tanδμ was 0.03.

[0119] Example 9

[0120] This embodiment provides a method for preparing rare earth soft magnetic powder. The preparation method is the same as that of Example 1 except that the raw material SiO2 powder in step (1) is replaced by C powder, and T is the C element.

[0121] The composition of the rare earth soft magnetic powder obtained in this embodiment is Ce2Fe 16.6 Ni 0.2 C 0.2 N 2.8 , the average particle size is 82nm.

[0122] This embodiment also provides a soft magnetic composite material, which is prepared by mixing the above-mentioned rare earth soft magnetic powder with a binder. The preparation method is the same as that of Example 1.

[0123] The soft magnetic composite material obtained in this embodiment was made into a ring sample and tested with a vector network analyzer at a frequency of 1 GHz. The results showed that the magnetic permeability μ' was 4.38 and the magnetic loss tanδμ was 0.11.

[0124] Comparative Example 1

[0125] This comparative example provides a method for preparing rare earth soft magnetic powder. The preparation method is the same as Example 1 except that the heating temperature in step (3) is 700° C. and the heating time is 10 h.

[0126] The rare earth soft magnetic powder obtained in this comparative example did not form a phase composition of Ce2Fe 17-x-y Ni x T y N z The surface-type structure, a large amount of α-Fe phase appears in the rare earth soft magnetic powder.

[0127] Comparative Example 2

[0128] This comparative example provides a method for preparing rare earth soft magnetic powder. The preparation method is the same as Example 1 except that the heating temperature in step (3) is 350° C. and the heating time is 10 h.

[0129] The composition of the rare earth soft magnetic powder obtained in this embodiment is Ce2Fe 16.6 Ni 0.2 C 0.2 N 1.1 , the average particle size is 41nm.

[0130] This comparative example also provides a soft magnetic composite material, which is prepared by mixing the above-mentioned rare earth soft magnetic powder with a binder. The preparation method is the same as that of Example 1.

[0131] The soft magnetic composite material obtained in this comparative example was made into a ring sample and tested using a vector network analyzer at a frequency of 1 GHz. The results showed a magnetic permeability μ' of 4.08 and a magnetic loss tan δμ of 0.28. The soft magnetic composite material obtained in this comparative example had a low nitrogen content, resulting in a significantly increased magnetic loss.

[0132] In summary, the preparation method of rare earth soft magnetic powder and the preparation method of soft magnetic composite material provided by the present invention are simple to operate and have low preparation cost. The soft magnetic composite material finally obtained is suitable for high-frequency working conditions, especially can meet the use of electronic devices under GHz working conditions.

[0133] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection 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 scope of protection and disclosure of the present invention.

Claims

1. A method for preparing rare earth soft magnetic powder, characterized in that: The rare earth soft magnetic powder includes Ce2Fe 17-x- y Ni x T y N z , wherein T includes any one of Si, C or B or a combination of at least two thereof; x, y, and z are the atomic contents of Ni, T, and N, respectively, with x being 0.1 to 0.5, y being 0.1 to 0.5, and z being 2 to 4; The preparation method comprises the following steps: (1) Raw materials Fe2O3 powder, Ce2O3 powder, Ni2O3 powder, SiO2 powder, C powder and B2O3 powder, according to Ce2Fe 17-x- y Ni x T y N z mixing to obtain a mixed powder; (2) After the mixed powder is heat-treated in a hydrogen atmosphere, it is mixed with a reducing agent and an auxiliary agent, and subjected to vacuum heating treatment to obtain an intermediate product with a loose texture; (3) The intermediate product is subjected to a smelting treatment and a rapid cooling treatment in sequence, and then heated in a nitrogen atmosphere to undergo crystallization and nitridation reactions to obtain a reacted substance; the heating temperature is 400-550° C.; (4) mixing the reacted substance with an acetic acid solution, stirring and solid-liquid separation in sequence to obtain the rare earth soft magnetic powder.

2. The preparation method according to claim 1, characterized in that The rare earth soft magnetic powder may be in a flake shape.

3. The preparation method according to claim 1, characterized in that The average particle size of the rare earth soft magnetic powder is 50-100 nm.

4. The preparation method according to claim 1, characterized in that The purity of hydrogen in the hydrogen atmosphere in step (2) is >99.9%.

5. The preparation method according to claim 1, characterized in that The reducing agent includes metallic calcium.

6. The preparation method according to claim 1, characterized in that The auxiliary agent includes B2O3 powder.

7. The preparation method according to claim 1, characterized in that The heating step of the vacuum heating treatment in step (2) includes: first heating to 800°C, and then filling with argon gas and heating to 1000°C.

8. The preparation method according to claim 1, characterized in that After the vacuum heating treatment, the temperature is cooled to 20-30°C.

9. The preparation method according to claim 1, characterized in that The temperature of the smelting treatment in step (3) is 1300-1500°C.

10. The preparation method according to claim 1, characterized in that The rapid cooling process is achieved by the following method: the molten liquid after the smelting process flows through a quartz nozzle onto a high-speed rotating molybdenum roller to be rapidly cooled to form a glassy mixture.

11. The preparation method according to claim 10, characterized in that: The rotation speed of the molybdenum roller is 20 to 25 m / s.

12. The preparation method according to claim 1, characterized in that The heating time is 6 to 10 hours.

13. A soft magnetic composite material, characterized in that: The soft magnetic composite material is prepared by mixing rare earth soft magnetic powder prepared by the method for preparing rare earth soft magnetic powder according to any one of claims 1 to 12 with a binder; the rare earth soft magnetic powder accounts for 20% to 70% of the mass of the soft magnetic composite material.

14. A method for preparing the soft magnetic composite material according to claim 13, characterized in that: The preparation method comprises the following steps: (a) mixing epoxy resin and acetone to obtain a mixed solution; mixing and stirring the mixed solution with rare earth soft magnetic powder to obtain rare earth soft magnetic powder coated with epoxy resin; (b) The rare earth soft magnetic powder coated with epoxy resin is dried, mixed with a thermoplastic binder, kneaded and granulated to obtain the soft magnetic composite material.

15. The preparation method according to claim 14, characterized in that The volume ratio of the mixed solution to the rare earth soft magnetic powder in step (a) is 1.5:1 to 2:

1.

16. The preparation method according to claim 14, characterized in that The thermoplastic binder in step (b) includes any one of nylon 6, nylon 12 or polyphenylene sulfide, or a combination of at least two of them.

17. The preparation method according to claim 14, characterized in that The added amount of the thermoplastic binder accounts for 17-67% of the mass of the rare earth soft magnetic powder coated with epoxy resin.

18. The preparation method according to claim 14, characterized in that The mixing temperature is 5 to 10° C. higher than the softening temperature of the thermoplastic binder.

19. The preparation method according to claim 14, characterized in that During the mixing process, argon gas is introduced for protection.