Soft magnetic material and preparation method thereof

Abstract

The invention relates to the field of soft magnetic materials, and particularly provides a preparation method of a soft magnetic material, which comprises the following steps: S1, mixing a soft magnetic material to be treated with a binder in the presence of a solvent to obtain mixed slurry; s2, carrying out atomization granulation on the mixed slurry to respectively obtain particles with different granularities; s3, the particles with different particle sizes are mixed, and the soft magnetic material is prepared, the mixed slurry containing the soft magnetic material, the binder and the solvent is subjected to atomization granulation to obtain the soft magnetic particles with different particle size ranges, the particles with mismatched sizes can be obtained after compounding, the obtained particles have obviously improved fluidity and increased apparent density, and the prepared soft magnetic material has good stability. The problems of poor product consistency, surface die drawing, internal cracking and short service life of the die can be solved.

Description

Technical Field

[0001] The invention relates to the field of soft magnetic materials, and in particular to a method for preparing soft magnetic materials. Background Art

[0002] As an important magnetic functional material, soft magnetic materials play a role in energy conversion and coupling in electronic devices. They are widely used in communications, information technology, power equipment, automatic control and other fields. They have high saturation magnetization, good frequency characteristics, good heat dissipation and other advantages. They realize the high frequency, high width constant magnetic conductivity and high quality factor of inductor devices, promote the use of electronic components in high frequency, high energy efficiency, high current and miniaturization scenarios, and have very broad market prospects. After the soft magnetic material is coated and mixed with the insulating binder, the soft magnetic powder core is prepared through molding, annealing, impregnation and curing. It is increasingly used in photovoltaic inverters, uninterruptible power supplies and other fields, and the market size is growing.

[0003] The fluidity of powder is critical to the molding of metal magnetic powder cores. Good fluidity can solve problems such as poor product consistency, surface die pulling, internal cracking, short mold life, etc., affecting product quality and increasing product costs. Currently, there is an urgent need to provide a method to improve the fluidity of soft magnetic materials. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect of poor fluidity of soft magnetic materials in the prior art, thereby providing a soft magnetic material and a preparation method thereof.

[0005] To this end, the present application provides a method for preparing a soft magnetic material, comprising the following steps:

[0006] Step S1: mixing the soft magnetic material to be treated with a binder in the presence of a solvent to obtain a mixed slurry;

[0007] Step S2, atomizing and granulating the mixed slurry to obtain particles of different particle sizes;

[0008] Step S3: Mix particles of different sizes to obtain a soft magnetic material.

[0009] Furthermore, the particles of different sizes include first particles larger than 60 mesh, second particles between 60 mesh and 100 mesh, third particles between 100 mesh and 150 mesh, fourth particles between 150 mesh and 200 mesh, and fifth particles smaller than 200 mesh.

[0010] In this application, larger than 60 mesh means that the particles cannot pass through a 60 mesh screen.

[0011] Between 60 mesh and 100 mesh means that the particles cannot pass through a 100 mesh screen, but can pass through a 60 mesh screen.

[0012] Between 150 mesh and 200 mesh means that the particles cannot pass through a 200-mesh sieve but can pass through a 150-mesh sieve.

[0013] Less than 200 mesh means that the particles can pass through a 200-mesh sieve.

[0014] Furthermore, the mass ratio m1 of the first particles in the soft magnetic material satisfies 0 < m1 ≤ 10 wt%; preferably 3 ≤ m1 ≤ 8 wt%;

[0015] The mass ratio m2 of the second particles in the soft magnetic material satisfies 0 < m2 ≤ 60 wt%; preferably 10 ≤ m2 ≤ 50 wt%;

[0016] The mass ratio m3 of the third particles in the soft magnetic material satisfies 0 < m3 ≤ 50 wt%; preferably 10 ≤ m3 ≤ 50 wt%;

[0017] The mass ratio m4 of the fourth particles in the soft magnetic material satisfies 0 < m4 ≤ 40 wt%; preferably 10 ≤ m4 ≤ 35 wt%;

[0018] The mass ratio m5 of the fifth particles in the soft magnetic material satisfies 0 < m5 ≤ 10 wt%; preferably 1 ≤ m5 ≤ 7 wt%.

[0019] Furthermore, m1, m2, m3, m4, and m5 satisfy the following relational expression:

[0020] 5 ≤ (m2 + m3 + m4) / (m1 + m5) ≤ 34;

[0021] Preferably, 8 ≤ (m2 + m3 + m4) / (m1 + m5) ≤ 20.

[0022] Furthermore, the gas pressure for atomization granulation is 0.1 MPa to 3 MPa, and the nozzle diameter is 0.1 mm to 1 mm; preferably, the gas pressure for atomization granulation to obtain the first particles is 0.1 MPa to 0.3 MPa, and the nozzle diameter is 0.85 mm to 1 mm;

[0023] The gas pressure for atomization granulation to obtain the second particles is 0.8 MPa to 1.3 MPa, and the nozzle diameter is 0.73 mm to 0.95 mm;

[0024] The gas pressure for atomization granulation to obtain the third particles is 1.2 MPa to 1.65 MPa, and the nozzle diameter is 0.45 mm to 0.61 mm;

[0025] The gas pressure for atomization granulation to obtain the fourth particles is 2.5 MPa to 2.83 MPa, and the nozzle diameter is 0.22 mm to 0.39 mm;

[0026] The gas pressure of the atomization granulation of the fifth particles is 2.79 MPa to 3.0 MPa, and the nozzle diameter is 0.10 mm to 0.25 mm.

[0027] Furthermore, the atomization granulation process also includes the step of introducing preheated gas into the mixed slurry;

[0028] Optionally, the gas includes air or nitrogen;

[0029] Optionally, the preheating temperature is 60-150°C.

[0030] Furthermore, the preparation method satisfies one or more of the following AD:

[0031] A. The binder includes a resin binder. Preferably, the binder is selected from at least one of phenolic resin, epoxy resin, and ketone-alcohol resin;

[0032] B. The mass percentage of the binder to the soft magnetic material is 0.5 to 2.5 wt %;

[0033] C. The mass ratio of the soft magnetic material to the volume of the solvent is 100 g: 5-30 mL;

[0034] D. The solvent includes one or more of acetone, ethanol, methanol, acetonitrile and dimethyl sulfoxide.

[0035] Further, the soft magnetic material to be processed includes one or more of sendustine, iron silicon, iron nickel, iron nickel molybdenum, amorphous / nanocrystalline;

[0036] Preferably, the particle size D50 of the soft magnetic material to be processed is 1 to 100 μm, more preferably 10 to 20 μm.

[0037] Furthermore, before the step S1, the soft magnetic material to be processed is subjected to a passivation treatment and / or the mixing process of the step S1 also includes a step of adding an insulating agent;

[0038] Preferably, the insulating agent includes one or more of oxides and silicone resins; more preferably, the oxide includes one or more of magnesium oxide, silicon oxide, and aluminum oxide; more preferably, the silicone resin includes polyalkyl aryl silicone resin;

[0039] Preferably, in the passivation treatment process, the passivating agent used includes an acid; more preferably, the acid includes one or more of sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, and chromic acid;

[0040] Preferably, the insulating agent accounts for 0.1 to 5 wt% of the mass of the soft magnetic material;

[0041] Preferably, during the passivation treatment, the percentage of the passivating agent used in the mass of the soft magnetic material is 0.1-3 wt%.

[0042] In this application, both the passivation treatment and / or the insulation coating treatment adopt conventional methods. Specifically, the passivation treatment includes mixing the soft magnetic powder to be treated with a passivating agent and then stirring. The stirring time can be 5-30 min.

[0043] This application also provides a soft magnetic material prepared by the preparation method of any of the above-mentioned soft magnetic materials.

[0044] The technical solution of the present invention has the following advantages:

[0045] 1. The preparation method of the soft magnetic material provided by the present invention includes the following steps: Step S1: Mix the soft magnetic material to be treated with a binder in the presence of a solvent to obtain a mixed slurry; Step S2: Atomize and granulate the mixed slurry to obtain particles of different particle sizes; Step S3: Mix the particles of different particle sizes to prepare a soft magnetic material. The present invention obtains soft magnetic particles in different particle size ranges by atomizing and granulating a mixed slurry containing a soft magnetic material, a binder and a solvent. After compounding, particles with size mismatch can be obtained, and the obtained particles have significantly improved fluidity and increased loose bulk density, which can solve the problems of poor product consistency, surface drawing die, internal cracking, and short die life.

[0046] 2. In the preparation method of the soft magnetic material provided by the present invention, the particles of different particle sizes include first particles larger than 60 mesh, second particles between 60 mesh and 100 mesh, third particles between 100 mesh and 150 mesh, fourth particles between 150 mesh and 200 mesh, and fifth particles smaller than 200 mesh. A soft magnetic material with higher fluidity is obtained by compounding the above five kinds of particles. The mass ratio m1 of the first particles in the soft magnetic material satisfies 0 < m1 ≤ 10 wt%; preferably 3 ≤ m1 ≤ 8 wt%; the mass ratio m2 of the second particles in the soft magnetic material satisfies 0 < m2 ≤ 60 wt%; preferably 10 ≤ m2 ≤ 50 wt%; the mass ratio m3 of the third particles in the soft magnetic material satisfies 0 < m3 ≤ 50 wt%; preferably 10 ≤ m3 ≤ 50 wt%; the mass ratio m4 of the fourth particles in the soft magnetic material satisfies 0 < m4 ≤ 40 wt%; preferably 10 ≤ m4 ≤ 35 wt%; the mass ratio m5 of the fifth particles in the soft magnetic material satisfies 0 < m5 ≤ 10 wt%; preferably 1 ≤ m5 ≤ 7 wt%; by controlling the mass content of the five kinds of particles within the above range, especially within the preferred range, the fluidity of the particles can be further improved.

[0047] 3. In the preparation method of soft magnetic material provided by the present invention, m1, m2, m3, m4, and m5 satisfy the following relationship: 5≤(m2+m3+m4) / (m1+m5)≤34; preferably, 8≤(m2+m3+m4) / (m1+m5)≤20. The fluidity of the particles can be further improved by controlling the ratio of the sum of m2, m3, and m4 to the sum of m1 and m5 within the above range, especially within the preferred range.

[0048] 4. The method for preparing the soft magnetic material provided by the present invention does not require a screening step, has high efficiency, low cost, and is conducive to mass production.

[0049] 5. The method for preparing the soft magnetic material provided by the present invention obtains spherical particles by atomization granulation, and can accurately control the granulation particle size by adjusting the gas pressure to 0.1MPa-3MPa, the nozzle diameter to 0.1mm-1mm, and passing preheated gas at a temperature of 60-150°C into the mixed slurry for drying, so as to obtain soft magnetic powder particles of different particle size ranges, and carry out particle size compounding, improve the fluidity and bulk density of the soft magnetic powder, and solve the problems of poor product consistency, surface die drawing, internal cracking, and short die life. The operation is simple and the production efficiency is high. DETAILED DESCRIPTION

[0050] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0051] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0052] Example 1

[0053] A method for preparing high-fluidity soft magnetic powder comprises the following steps:

[0054] (1) Passivation treatment: 100g of iron-nickel soft magnetic powder (molecular formula Fe 50 Ni 50 ) was added with 0.1 wt % phosphoric acid accounting for the mass of the soft magnetic powder, stirred for 5 min, washed and dried to obtain a first powder.

[0055] (2) Coating treatment: 0.5 wt% of the phenolic resin by weight of the first powder is dissolved in 10 mL of acetone, and then mixed evenly with 0.5 wt% of the silicon oxide by weight of the first powder and the first powder to form a mixed slurry.

[0056] (3) Atomization granulation: The mixed slurry is poured into a sprayer and granulated by high-pressure gas spraying. The droplets are sprayed into a collection tank. Flowing air is introduced into the collection tank. The gas is heated before entering the tank. The heating temperature is 60°C. The gas pressure and nozzle diameter are adjusted to obtain first particles larger than 60 mesh, second particles between 60 mesh and 100 mesh, third particles between 100 mesh and 150 mesh, fourth particles between 150 mesh and 200 mesh, and fifth particles smaller than 200 mesh, a total of 5 groups of powder particles, wherein the gas pressures of the first particles, the second particles, the third particles, the fourth particles, and the fifth particles are 0.10 MPa, 0.83 MPa, 1.22 MPa, 2.54 MPa, and 2.83 MPa, respectively, and the nozzle diameters are 0.88 mm, 0.73 mm, 0.47 mm, 0.22 mm, and 0.10 mm, respectively. The first particle, the second particle, the third particle, the fourth particle and the fifth particle are compounded in a ratio of 5wt%: 45wt%: 35wt%: 10wt%: 5wt% respectively, and are fully mixed to obtain compounded soft magnetic powder.

[0057] Example 2

[0058] A method for preparing high-fluidity soft magnetic powder comprises the following steps:

[0059] (1) Passivation treatment: 100g of iron-nickel soft magnetic powder (molecular formula Fe 50 Ni 50 ) was added with 0.5 wt % phosphoric acid accounting for the mass of the soft magnetic powder, stirred for 10 min, washed and dried to obtain a first powder.

[0060] (2) Coating treatment: 0.8 wt% of the phenolic resin by weight of the first powder is dissolved in 10 mL of acetone, and then mixed with 1 wt% of the magnesium oxide by weight of the first powder and the first powder to form a mixed slurry.

[0061] (3) Atomization granulation: The mixed slurry is poured into a sprayer and granulated by high-pressure gas spraying. The droplets are sprayed into a collection tank. Flowing air is introduced into the collection tank. The gas is heated before entering the tank. The heating temperature is 80°C. The gas pressure and nozzle diameter are adjusted to obtain first particles larger than 60 mesh, second particles between 60 mesh and 100 mesh, third particles between 100 mesh and 150 mesh, fourth particles between 150 mesh and 200 mesh, and fifth particles smaller than 200 mesh, a total of 5 groups of powder particles, wherein the gas pressures of the first particles, the second particles, the third particles, the fourth particles, and the fifth particles are 0.12 MPa, 0.95 MPa, 1.37 MPa, 2.63 MPa, and 2.89 MPa, respectively, and the nozzle diameters are 0.89 mm, 0.76 mm, 0.49 mm, 0.27 mm, and 0.14 mm, respectively. The first particle, the second particle, the third particle, the fourth particle and the fifth particle are compounded in a ratio of 8wt%: 50wt%: 30wt%: 10wt%: 2wt% respectively, and are fully mixed to obtain compounded soft magnetic powder.

[0062] Example 3

[0063] A method for preparing high-fluidity soft magnetic powder comprises the following steps:

[0064] (1) Passivation treatment: 100g of iron-nickel soft magnetic powder (molecular formula Fe 50 Ni 50 ) was added with 0.5 wt % phosphoric acid accounting for the mass of the soft magnetic powder, stirred for 15 min, washed and dried to obtain a first powder.

[0065] (2) Coating treatment: 1.4 wt% of the phenolic resin by weight of the first powder is dissolved in 10 mL of acetone, and then mixed evenly with 1 wt% of the alumina by weight of the first powder and the first powder to form a mixed slurry.

[0066] (3) Atomization granulation: The mixed slurry is poured into a sprayer and granulated by high-pressure gas spraying. The droplets are sprayed into a collection tank. Flowing air is introduced into the collection tank. The gas is heated before entering the tank. The heating temperature is 100°C. The gas pressure and nozzle diameter are adjusted to obtain first particles larger than 60 mesh, second particles between 60 mesh and 100 mesh, third particles between 100 mesh and 150 mesh, fourth particles between 150 mesh and 200 mesh, and fifth particles smaller than 200 mesh, a total of 5 groups of powder particles, wherein the gas pressures of the first particles, the second particles, the third particles, the fourth particles, and the fifth particles are 0.25 MPa, 1.18 MPa, 1.56 MPa, 2.75 MPa, and 2.97 MPa, respectively, and the nozzle diameters are 0.97 mm, 0.85 mm, 0.58 mm, 0.36 mm, and 0.21 mm, respectively. The first particle, the second particle, the third particle, the fourth particle and the fifth particle are compounded in a ratio of 3wt%: 50wt%: 10wt%: 30wt%: 7wt% respectively, and are fully mixed to obtain compounded soft magnetic powder.

[0067] Example 4

[0068] A method for preparing high-fluidity soft magnetic powder comprises the following steps:

[0069] (1) Passivation treatment: 100g of iron-nickel soft magnetic powder (molecular formula Fe 50 Ni 50 ) was added with 0.5 wt % phosphoric acid accounting for the mass of the soft magnetic powder, stirred for 20 min, washed and dried to obtain a first powder.

[0070] (2) Coating treatment: 1 wt% of the phenolic resin by weight of the first powder is dissolved in 10 mL of acetone, and then mixed evenly with 1.5 wt% of the aluminum oxide by weight of the first powder and the first powder to form a mixed slurry.

[0071] (3) Atomization granulation: The mixed slurry is poured into a sprayer and granulated by high-pressure gas spraying. The droplets are sprayed into a collection tank. Flowing air is introduced into the collection tank. The gas is heated before entering the tank. The heating temperature is 120°C. The gas pressure and nozzle diameter are adjusted to obtain first particles larger than 60 mesh, second particles between 60 mesh and 100 mesh, third particles between 100 mesh and 150 mesh, fourth particles between 150 mesh and 200 mesh, and fifth particles smaller than 200 mesh, a total of 5 groups of powder particles, wherein the gas pressures of the first particles, the second particles, the third particles, the fourth particles, and the fifth particles are 0.19 MPa, 1.07 MPa, 1.43 MPa, 2.68 MPa, and 2.94 MPa, respectively, and the nozzle diameters are 0.91 mm, 0.79 mm, 0.52 mm, 0.30 mm, and 0.17 mm, respectively. The first particle, the second particle, the third particle, the fourth particle and the fifth particle are compounded in a ratio of 5wt%: 30wt%: 30wt%: 30wt%: 5wt% respectively, and are fully mixed to obtain compounded soft magnetic powder.

[0072] Example 5

[0073] A method for preparing high-fluidity soft magnetic powder comprises the following steps:

[0074] (1) Passivation treatment: 100g of iron-nickel soft magnetic powder (molecular formula Fe 50 Ni 50 ) was added with phosphoric acid accounting for 1.5 wt % of the mass of the soft magnetic powder, stirred for 25 min, washed and dried to obtain a first powder.

[0075] (2) Coating treatment: A polyalkylaryl silicone resin with a solid content of 50% accounting for 2 wt% of the mass of the first powder and a phenolic resin accounting for 1.2 wt% of the mass of the first powder are dissolved in 10 mL of acetone and then mixed evenly with alumina accounting for 1.5 wt% of the mass of the first powder and the first powder to form a mixed slurry.

[0076] (3) Atomization granulation: The mixed slurry is poured into a sprayer and granulated by high-pressure gas spraying. The droplets are sprayed into a collection tank. Flowing air is introduced into the collection tank. The gas is heated before entering the tank. The heating temperature is 60°C. The gas pressure and nozzle diameter are adjusted to obtain first particles larger than 60 mesh, second particles between 60 mesh and 100 mesh, third particles between 100 mesh and 150 mesh, fourth particles between 150 mesh and 200 mesh, and fifth particles smaller than 200 mesh, a total of 5 groups of powder particles, wherein the gas pressures of the first particles, the second particles, the third particles, the fourth particles, and the fifth particles are 0.22 MPa, 1.15 MPa, 1.52 MPa, 2.71 MPa, and 2.95 MPa, respectively, and the nozzle diameters are 0.95 mm, 0.83 mm, 0.54 mm, 0.31 mm, and 0.19 mm, respectively. The first particle, the second particle, the third particle, the fourth particle and the fifth particle are compounded in a ratio of 5wt%: 30wt%: 50wt%: 10wt%: 5wt% respectively, and are fully mixed to obtain compounded soft magnetic powder.

[0077] Example 6

[0078] A method for preparing high-fluidity soft magnetic powder comprises the following steps:

[0079] (1) Passivation treatment: 100g of iron-nickel soft magnetic powder (molecular formula Fe 50 Ni 50 ) was added with 2 wt % phosphoric acid of the soft magnetic powder, stirred for 5 min, washed and dried to obtain a first powder.

[0080] (2) Coating treatment: Dissolve a polyalkylaryl silicone resin with a solid content of 70% accounting for 1.5 wt% of the mass of the first powder and a phenolic resin accounting for 1.5 wt% of the mass of the first powder in 10 mL of acetone, and then mix them evenly with alumina accounting for 1.5 wt% of the mass of the first powder and the first powder to form a mixed slurry.

[0081] (3) Atomization granulation: The mixed slurry is poured into a sprayer and granulated by high-pressure gas spraying. The droplets are sprayed into a collection tank. Flowing air is introduced into the collection tank. The gas is heated before entering the tank. The heating temperature is 60°C. The gas pressure and nozzle diameter are adjusted to obtain first particles larger than 60 mesh, second particles between 60 mesh and 100 mesh, third particles between 100 mesh and 150 mesh, fourth particles between 150 mesh and 200 mesh, and fifth particles smaller than 200 mesh, a total of 5 groups of powder particles, wherein the gas pressures of the first particles, the second particles, the third particles, the fourth particles, and the fifth particles are 0.29 MPa, 1.23 MPa, 1.61 MPa, 2.79 MPa, and 3.00 MPa, respectively, and the nozzle diameters are 1.00 mm, 0.91 mm, 0.61 mm, 0.39 mm, and 0.24 mm, respectively. The first particle, the second particle, the third particle, the fourth particle and the fifth particle are compounded in a ratio of 4wt%: 10wt%: 50wt%: 35wt%: 1wt% respectively, and are fully mixed to obtain compounded soft magnetic powder.

[0082] Example 7

[0083] This embodiment is basically the same as embodiment 1, except that step (1) is omitted and silicon oxide is not added in step (2). The remaining steps are the same as embodiment 1.

[0084] Example 8

[0085] This embodiment is basically the same as Embodiment 1, the only difference being that the particle compounding ratio is different. In this embodiment, five groups of powder particles having a size greater than 60 mesh, between 60 mesh and 100 mesh, between 100 mesh and 150 mesh, between 150 mesh and 200 mesh, and less than 200 mesh are compounded in a ratio of 1wt%: 41wt%: 27wt%: 29wt%: 2wt% and fully mixed to obtain the compounded soft magnetic powder.

[0086] Example 9

[0087] This embodiment is basically the same as Embodiment 1, the only difference being that the particle compounding ratio is different. In this embodiment, five groups of powder particles having a size larger than 60 mesh, between 60 mesh and 100 mesh, between 100 mesh and 150 mesh, between 150 mesh and 200 mesh, and less than 200 mesh are compounded in a ratio of 8wt%: 40wt%: 20wt%: 25wt%: 7wt% and fully mixed to obtain the compounded soft magnetic powder.

[0088] Comparative Example 1

[0089] This comparative example provides a method for preparing soft magnetic powder, which is basically the same as Example 1, except that in step (3), no atomization granulation is performed, but the powder is naturally dried to a semi-dry state with a moisture content of 3%, and then granulated through a 60-mesh sieve. After drying, the powder is sieved with a 60-mesh sieve to obtain a soft magnetic powder.

[0090] Comparative Example 2

[0091] This comparative example provides a method for preparing soft magnetic powder, which is basically the same as Example 2, except that in step (3), no atomization granulation is performed, but the powder is naturally dried to a semi-dry state with a moisture content of 3%, and then granulated through a 100-mesh sieve. After drying, the powder is sieved to a mesh size of 150 to obtain a soft magnetic powder.

[0092] Comparative Example 3

[0093] This comparative example provides a method for preparing soft magnetic powder, which is basically the same as Example 3, except that in step (3), no atomization granulation is performed, but the powder is naturally dried to a semi-dry state with a moisture content of 3%, and then granulated through a 150-mesh sieve. After drying, the powder is sieved with a 60-mesh sieve to obtain a soft magnetic powder.

[0094] Comparative Example 4

[0095] This comparative example provides a method for preparing a soft magnetic powder, which is basically the same as Example 4, except that in step (3), no atomization granulation is performed, but the powder is naturally aired to a semi-dry state with a moisture content of 3%, and then granulated through a 60-mesh sieve. After drying, the powder is sieved with mesh sizes of 60, 100, 150, and 200, to obtain five groups of powder particles with particle sizes ranging from greater than 60 mesh, between 60 and 100 mesh, between 100 and 150 mesh, between 150 and 200 mesh, and less than 200 mesh. The powder particles are compounded in a ratio of 5wt%: 30wt%: 30wt%: 30wt%: 5wt%, and fully mixed to obtain the compounded soft magnetic powder.

[0096] Comparative Example 5

[0097] This comparative example provides a method for preparing a soft magnetic powder, which is basically the same as Example 5, except that in step (3), no atomization granulation is performed, but the powder is naturally aired to a semi-dry state with a moisture content of 3%, and then granulated through a 100-mesh sieve. After drying, the powder is sieved with mesh sizes of 60, 100, 150, and 200, to obtain five groups of powder particles with particle sizes ranging from greater than 60 mesh, between 60 and 100 mesh, between 100 and 150 mesh, between 150 and 200 mesh, and less than 200 mesh. The powder particles are compounded in a ratio of 5wt%: 30wt%: 50wt%: 10wt%: 5wt%, and fully mixed to obtain the compounded soft magnetic powder.

[0098] Comparative Example 6

[0099] This comparative example provides a method for preparing a soft magnetic powder, which is basically the same as Example 6, except that in step (3), no atomization granulation is performed, but the powder is naturally aired to a semi-dry state with a moisture content of 3%, and then granulated through a 150-mesh sieve. After drying, the powder is sieved with mesh sizes of 60, 100, 150, and 200, to obtain five groups of powder particles with particle sizes ranging from greater than 60 mesh, between 60 and 100 mesh, between 100 and 150 mesh, between 150 and 200 mesh, and less than 200 mesh. The powder particles are compounded in a ratio of 4wt%: 10wt%: 50wt%: 35wt%: 1wt%, and fully mixed to obtain the compounded soft magnetic powder.

[0100] Comparative Example 7

[0101] The method is basically the same as Example 1, except that step (3) only produces third particles with a size between 100 and 150 meshes, that is, the mass proportion of the third particles is 100%.

[0102] Test Example 1

[0103] The soft magnetic powders prepared in the examples and comparative examples were tested for fluidity and bulk density. The powder fluidity was tested using a Hall flowmeter. The material was added to a funnel and the time required for all the material to flow out was measured, and the time for 50g of powder to flow out was calculated. The bulk density was measured using a vibrating funnel method. The material was placed in a vibrating funnel, and the vibrator was turned on. The material was in a vibrating state. When the vibration reached a certain degree, the vibration was stopped, and a certain weight of sample was collected. The sample weight and volume were calculated to calculate the bulk density. See Table 1.

[0104] The soft magnetic powders prepared in the embodiment and the comparative example were respectively used to prepare sample rings according to the following method: 2 wt% of the mass of the soft magnetic powder was added to the soft magnetic material, and the sample rings were formed under a pressure of 1800 MPa and annealed at 700°C for 1 hour. Then, a copper wire with a diameter of 0.4 mm was wound around the magnetic ring for 20 turns. The test conditions were 100 kHz, 1 V, and 25°C. The relative magnetic permeability was calculated by testing the inductance value.

[0105] Table 1 Fluidity, bulk density and magnetic permeability

[0106]

[0107] It can be seen from the above table that the powders granulated and sieved with different mesh sizes and compounded with different particle sizes have significantly better fluidity and bulk density than the powders granulated and sieved with conventional granulation. The best performance is Example 5, whose fluidity and bulk density are 28s / 50g and 2.97g / cm3 In Comparative Example 5, the best powder flowability and bulk density are 37s / 50g and 2.71g / cm 3 .

[0108] Compared with Examples 8 and 9, Example 1 can further improve the fluidity of the soft magnetic powder by limiting (m2+m3+m4) / (m1+m5) within the preferred range.

[0109] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing a soft magnetic material, characterized in that: It includes the following steps: Step S1: Mix the soft magnetic material to be processed with a binder in the presence of a solvent to obtain a mixed slurry; Step S2: Atomize and granulate the mixed slurry to obtain particles with different particle sizes respectively; Step S3: Mix the particles with different particle sizes to prepare a soft magnetic material.

2. The method for preparing a soft magnetic material according to claim 1, characterized in that: The particles with different particle sizes include first particles larger than 60 mesh, second particles between 60 mesh and 100 mesh, third particles between 100 mesh and 150 mesh, fourth particles between 150 mesh and 200 mesh, and fifth particles smaller than 200 mesh.

3. The method for preparing a soft magnetic material according to claim 2, characterized in that: The mass ratio m1 of the first particles in the soft magnetic material satisfies 0 < m1 ≤ 10 wt%; preferably 3 ≤ m1 ≤ 8 wt%; The mass ratio m2 of the second particles in the soft magnetic material satisfies 0 < m2 ≤ 60 wt%; preferably 10 ≤ m2 ≤ 50 wt%; The mass ratio m3 of the third particles in the soft magnetic material satisfies 0 < m3 ≤ 50 wt%; preferably 10 ≤ m3 ≤ 50 wt%; The mass ratio m4 of the fourth particles in the soft magnetic material satisfies 0 < m4 ≤ 40 wt%; preferably 10 ≤ m4 ≤ 35 wt%; The mass ratio m5 of the fifth particles in the soft magnetic material satisfies 0 < m5 ≤ 10 wt%; preferably 1 ≤ m5 ≤ 7 wt%.

4. The method for preparing a soft magnetic material according to claim 3, characterized in that: m1, m2, m3, m4, and m5 satisfy the following relational expression: 5 ≤ (m2 + m3 + m4) / (m1 + m5) ≤ 34; Preferably, 8 ≤ (m2 + m3 + m4) / (m1 + m5) ≤ 20.

5. The method for preparing the soft magnetic material according to any one of claims 1 to 4, characterized in that: The gas pressure for atomization granulation is 0.1 MPa to 3 MPa, and the nozzle diameter is 0.1 mm to 1 mm; preferably, the gas pressure for atomization granulation to obtain the first particles is 0.1 MPa to 0.3 MPa, and the nozzle diameter is 0.85 mm to 1 mm; The gas pressure for atomization granulation to obtain the second particles is 0.8 MPa to 1.3 MPa, and the nozzle diameter is 0.73 mm to 0.95 mm; The gas pressure for atomization granulation to obtain the third particles is 1.2 MPa to 1.65 MPa, and the nozzle diameter is 0.45 mm to 0.61 mm; The gas pressure for atomization granulation to obtain the fourth particles is 2.5 MPa to 2.83 MPa, and the nozzle diameter is 0.22 mm to 0.39 mm; The gas pressure for atomization granulation of the fifth particles is 2.79 MPa to 3.0 MPa, and the nozzle diameter is 0.10 mm to 0.25 mm.

6. The method for preparing a soft magnetic material according to any one of claims 1 to 5, characterized in that: During the atomization granulation process, it also includes the step of introducing a preheated gas into the mixed slurry; Optionally, the gas includes air or nitrogen; Optionally, the preheating temperature is 60 - 150 °C.

7. The method for preparing a soft magnetic material according to any one of claims 1 to 6, characterized in that: The preparation method satisfies one or more of the following A - D: A. The binder includes a resin - type binder. Preferably, the binder is selected from at least one of phenolic resin, epoxy resin, and ketol resin; B. The mass percentage of the binder in the soft magnetic material is 0.5 - 2.5 wt%; C. The mass ratio of the soft magnetic material to the volume of the solvent is 100 g: 5 - 30 mL; D. The solvent includes one or more of acetone, ethanol, methanol, acetonitrile, and dimethyl sulfoxide.

8. The method for preparing a soft magnetic material according to any one of claims 1 to 7, characterized in that: The soft magnetic material to be processed includes one or more of sendust, iron silicon, iron nickel, iron nickel molybdenum, amorphous / nanocrystalline; Preferably, the particle size D50 of the soft magnetic material to be processed is 1 to 100 μm, more preferably 10 to 20 μm.

9. The method for preparing a soft magnetic material according to any one of claims 1 to 8, characterized in that: Before the step S1, the soft magnetic material to be processed may be subjected to passivation treatment and / or an insulating agent may be added during the mixing process of the step S1; Preferably, the insulating agent includes one or more of oxides and silicone resins; more preferably, the oxide includes one or more of magnesium oxide, silicon oxide, and aluminum oxide; more preferably, the silicone resin includes polyalkylaryl silicone resin; Preferably, in the passivation treatment process, the passivating agent used includes an acid; more preferably, the acid includes one or more of sulfuric acid, phosphoric acid, nitric acid, and chromic acid; Preferably, the insulating agent accounts for 0.1 to 5 wt% of the mass of the soft magnetic material; Preferably, during the passivation treatment, the percentage of the passivating agent used in the soft magnetic material is 0.1-3 wt %.

10. A soft magnetic material obtained by the method for preparing a soft magnetic material according to any one of claims 1 to 9.

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