A soft magnetic powder core, a preparation method thereof and application thereof

Abstract

The present application relates to a kind of soft magnetic powder core and its preparation method and application, the soft magnetic powder core includes soft magnetic amorphous powder and insulating coating, the insulating coating is polydopamine / polyvinyl alcohol layer.Polydopamine / polyvinyl alcohol layer is coated on the surface of soft magnetic amorphous powder, polydopamine / polyvinyl alcohol layer is coated on the surface of soft magnetic amorphous powder, catechol group of polydopamine forms surface interaction with the surface of soft magnetic amorphous powder, its hydroxyl functional group can form hydrogen bond with the group of polyvinyl alcohol, constructs three-dimensional network insulating coating structure, improves the mechanical properties of the surface of soft magnetic powder core, so as to improve the high-frequency stability of soft magnetic powder core, effectively widen the application of soft magnetic powder core in high frequency field.

Description

Technical Field

[0001] This invention belongs to the field of soft magnetic materials technology, and relates to a soft magnetic powder core, its preparation method and application. Background Technology

[0002] Soft magnetic powder cores are manufactured by mixing soft magnetic powder with insulating materials such as resin using powder metallurgy. In recent years, with the development of electronic and electrical products towards high performance and lightweight designs, higher demands have been placed on the saturation magnetic induction, coercivity, and permeability of soft magnetic powder cores. Iron-based amorphous materials, due to their smaller related structures and the absence of grain boundaries, exhibit lower coercivity. However, with increasing operating frequency, the core loss of amorphous soft magnetic alloys also increases rapidly. Therefore, reducing the magnetic loss of high-frequency amorphous soft magnetic powder cores is currently a crucial factor restricting the industry's development.

[0003] The core loss of soft magnetic powder cores can be divided into hysteresis loss, eddy current loss, and residual loss. In high-frequency applications, eddy current loss is dominant. Reducing eddy current loss typically involves increasing the resistivity of the powder itself. Since amorphous alloys have higher resistivity than crystalline alloys, reducing eddy current loss in amorphous powder cores mainly focuses on improving the insulation between the powder particles. The insulating layer between powder particles is usually achieved using adhesives such as epoxy resin and phenolic resin, which improves both the insulation and mechanical properties of the product. However, this insulating layer often has poor uniformity and is easily punctured by the powder during pressing, causing short circuits.

[0004] CN 102314986A discloses a method for manufacturing an iron-silicon alloy magnetic powder core. The method involves heating iron-silicon magnetic powder to 50-150℃, then adding 0.8-3.2% (by weight) of phosphate for surface passivation. After drying, 0.3-1.5% phenolic resin is added, followed by further drying, pressing, and heat treatment to obtain an iron-silicon metal soft magnetic powder core. However, this method suffers from the gradual decomposition of the phosphate insulation layer during heat treatment, leading to a sharp decrease in resistivity, rapid increase in magnetic powder core loss, and aging problems.

[0005] CN 112562956A discloses a magnetic powder core material with stable magnetic permeability and low loss, and its preparation method. First, an alkaline modifier is added to iron powder to perform mechanochemical modification of the iron powder surface. Then, the modified iron powder is ball-milled and dry-mixed with nano-ferrite powder. Next, a binder, modified powder, and iron / ferrite composite powder are mixed, stirred, pressed, and heat-treated to obtain the magnetic powder core. However, during the preparation process, the composite powder exhibits significant internal stress, requiring a high heat treatment temperature, which leads to further oxidation of the magnetic powder and a substantial decrease in magnetic permeability at high frequencies.

[0006] CN 114068123A discloses a soft magnetic powder composite, a magnetic powder core material, and an insulating coating method based on organic growth. The method uses a polydopamine / polyethyleneimine layer to insulatingly coat the soft magnetic powder, effectively reducing eddy current losses between magnetic powder particles and obtaining a low-loss soft magnetic powder core. However, in this method, polyethyleneimine reacts with dopamine hydrochloride during self-polymerization, inhibiting the formation of dopamine covalent aggregates, which adversely affects the uniformity and stability of the surface coating. Simultaneously, polyethyleneimine has a high cationic charge density and hygroscopicity, negatively impacting the insulating properties of the coating layer.

[0007] Ideally, the coating material should tightly coat the surface of the metal powder and remain intact and dense after compaction and heat treatment. Therefore, improving the uniformity of the insulating layer coating and enhancing the product's characteristics at high frequencies has become a major focus in recent years. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a soft magnetic powder core, in which a polydopamine / polyacrylamide layer is coated on the surface of soft magnetic amorphous powder. The catechol groups of polydopamine form surface interactions with the surface of the soft magnetic amorphous powder, and its hydroxyl functional groups can form hydrogen bonds with the groups of polyacrylamide, thereby improving the mechanical properties of the soft magnetic powder core surface.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a soft magnetic powder core, the soft magnetic powder core comprising soft magnetic amorphous powder and an insulating coating layer, wherein the insulating coating layer is a polydopamine / polyacrylamide layer.

[0011] This invention coats the surface of soft magnetic amorphous powder with a polydopamine / polyacrylamide layer. The catechol groups of polydopamine form a surface interaction with the surface of the soft magnetic amorphous powder, and its hydroxyl functional groups can form hydrogen bonds with the groups of polyacrylamide, thus constructing a three-dimensional network insulating coating layer structure. This improves the mechanical properties of the soft magnetic powder core surface, thereby enhancing the high-frequency stability of the soft magnetic powder core and effectively broadening the application of soft magnetic powder cores in the high-frequency field.

[0012] Preferably, the soft magnetic amorphous powder includes any one or at least two combinations of Fe-Si-B, FeNiPB, CoZr, ZrTiCuNi, or FeSiAl. Typical but non-limiting combinations include Fe-Si-B and FeNiPB, FeNiPB and CoZr, CoZr and ZrTiCuNi, ZrTiCuNi and FeSiAl, Fe-Si-B, FeNiPB and CoZr, FeNiPB, CoZr and ZrTiCuNi, and CoZr, ZrTiCuNi and FeSiAl.

[0013] Preferably, the mass of the insulating coating layer is 0.03 to 0.052% of the mass of the soft magnetic powder core, for example, it can be 0.03%, 0.035%, 0.04%, 0.045% or 0.05%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] Preferably, the median particle size of the soft magnetic powder core is 10 to 60 μm, for example, it can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or 60 μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0015] Preferably, in the insulating coating layer, the mass ratio of polydopamine to polyacrylamide is (3-8):(2-7), for example, it can be 3:7, 4:6, 5:5, 6:4 or 8:2, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] In a second aspect, the present invention provides a method for preparing a soft magnetic powder core according to the first aspect, the method comprising the following steps:

[0017] (1) Mix soft magnetic amorphous powder and insulating coating material solution to obtain coated soft magnetic amorphous powder;

[0018] (2) Mix the coated soft magnetic amorphous powder and epoxy resin to obtain a mixed powder;

[0019] (3) The mixed powder is cold-pressed and then annealed to obtain the soft magnetic powder core.

[0020] Preferably, the soft magnetic amorphous powder in step (1) is a pretreated soft magnetic amorphous powder.

[0021] Preferably, the preprocessing method includes:

[0022] The soft magnetic amorphous powder raw material is cleaned, then subjected to alkaline treatment, and finally mixed with polyacryl alcohol solution to complete the pretreatment.

[0023] Preferably, the cleaning includes ultrasonic cleaning in an acetone solution and / or cleaning with deionized water.

[0024] Preferably, the ultrasonic cleaning time in the acetone solution is 5 to 15 minutes, for example, 5 minutes, 8 minutes, 10 minutes, 12 minutes or 15 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the alkaline treatment includes mixing the washed powder and alkaline solution and stirring.

[0026] Preferably, the alkaline solution comprises a NaOH solution of 0.2 to 0.8 mol / L, for example, 0.2 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L or 0.8 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the stirring time is 20 to 60 minutes, for example, 20 minutes, 30 minutes, 40 minutes, 50 minutes or 60 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the concentration of the polyacrylol solution is 30-80 mg / mL, for example, it can be 30 mg / mL, 40 mg / mL, 50 mg / mL, 60 mg / mL or 80 mg / mL, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0029] Preferably, the insulating coating material solution in step (1) comprises a mixed solution of dopamine hydrochloride and polyacryl alcohol.

[0030] In this invention, the raw material for polydopamine is dopamine hydrochloride. The self-polymerization reaction of dopamine hydrochloride is used to form a polydopamine layer on the surface of soft magnetic amorphous powder, which effectively improves the uniformity of the insulating coating layer, thereby further reducing the magnetic loss of the prepared soft magnetic powder core and improving high-frequency stability.

[0031] Preferably, the mass ratio of dopamine hydrochloride to polyacrylol is (3-8):(2-7), for example, it can be 3:7, 4:6, 5:5, 6:4 or 8:2, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the concentrations of dopamine hydrochloride and polyacrylamide in the insulating coating material solution are 6–35 mg / mL, for example, 6 mg / mL, 10 mg / mL, 15 mg / mL, 20 mg / mL or 35 mg / mL, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the solvent of the insulating coating material solution is a Tris solvent.

[0034] Preferably, the pH of the insulating coating material solution is 7.5 to 8.5, for example, it can be 7.5, 7.7, 8, 8.2 or 8.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the mixing in step (1) further includes heating.

[0036] Preferably, the heating temperature is 30 to 50°C, for example, 30°C, 35°C, 40°C, 45°C or 50°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the heating time is 20 to 48 hours, for example, 20 hours, 30 hours, 40 hours, 45 hours or 48 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, the epoxy resin in step (2) is an acetone solution of epoxy resin.

[0039] Preferably, in the mixing process described in step (2), the mass ratio of the coated soft magnetic amorphous powder to the epoxy resin is 40 to 70:1, for example, it can be 40:1, 45:1, 50:1, 60:1 or 70:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the mixing in step (2) includes stirring.

[0041] Preferably, the stirring continues until the solvent has completely evaporated.

[0042] Preferably, the mixing and stirring process further includes drying.

[0043] Preferably, the drying temperature is 40 to 105°C, for example, it can be 40°C, 60°C, 80°C, 100°C or 105°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] Preferably, the drying time is 3 to 6 hours, for example, 3 hours, 4 hours, 5 hours, 5.5 hours or 6 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] Preferably, the pressure of cold pressing in step (3) is 1.2 to 3.6 GPa, for example, it can be 1.2 GPa, 1.8 GPa, 2.4 GPa, 3 GPa or 3.6 GPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] Preferably, the annealing process is performed in a protective atmosphere.

[0047] Preferably, the annealing temperature is 300-600℃, for example, 300℃, 350℃, 400℃, 500℃ or 600℃, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0048] Preferably, the annealing time is 0.5 to 2 hours, for example, it can be 0.5 hours, 1 hour, 1.5 hours, 1.8 hours or 2 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0049] As a preferred embodiment of the preparation method described in the second aspect of the present invention, the preparation method includes the following steps:

[0050] (1) Mix pretreated soft magnetic amorphous powder with an insulating coating material solution with a pH of 7.5 to 8.5. The insulating coating material solution is a Tris mixed solution of dopamine hydrochloride and polyacrylamide, with a concentration of 6 to 35 mg / mL and a ratio of (3 to 8): (2 to 7). Heat in a water bath at 30 to 50°C for 20 to 48 hours to obtain coated soft magnetic amorphous powder.

[0051] (2) Mix the acetone solution of the coated soft magnetic amorphous powder and epoxy resin in a ratio of 40 to 70:1, stir until the acetone is completely evaporated, and then dry at 40 to 105°C for 3 to 6 hours to obtain the mixed powder.

[0052] (3) After the mixed powder is cold-pressed at a pressure of 1.2 to 3.6 GPa, it is annealed at 300 to 600°C for 0.5 to 2 hours in a protective atmosphere to obtain the soft magnetic powder core;

[0053] The preprocessing method is as follows:

[0054] The soft magnetic amorphous powder raw material is immersed in acetone for ultrasonic cleaning for 5-15 minutes, and then washed with deionized water 3-5 times to obtain the cleaned powder. The cleaned powder is mixed with 0.2-0.8 mol / L NaOH solution and stirred for 20-60 minutes, and then washed with deionized water until neutral to obtain the alkaline-treated powder. The alkaline-treated powder is immersed in a polyacryl alcohol solution with a concentration of 30-80 mg / mL for 20-60 minutes and then removed to obtain the pretreated soft magnetic amorphous powder.

[0055] Thirdly, the present invention provides an application of the soft magnetic powder core according to the first aspect, wherein the soft magnetic powder core is applied to an inductor or power device.

[0056] Compared with the prior art, the present invention has at least the following beneficial effects:

[0057] (1) The present invention coats the surface of soft magnetic amorphous powder with a polydopamine / polyacrylamide layer. The catechol groups of polydopamine form a surface interaction with the surface of soft magnetic amorphous powder, and its hydroxyl functional groups can form hydrogen bonds with the groups of polyacrylamide, thus constructing a three-dimensional network insulating coating layer structure, improving the mechanical properties of the soft magnetic powder core surface, thereby improving the high-frequency stability of the soft magnetic powder core and effectively broadening the application of soft magnetic powder core in the high-frequency field.

[0058] (2) The polydopamine / polyacrylamide layer can be maintained at 2.0 GPa without peeling, and the soft magnetic powder core has good insulation properties and low loss, ensuring a core loss of 521.3 mw / cm at 100 MHz. 3 .

[0059] (3) In the preparation method of the present invention, the raw material of polydopamine is dopamine hydrochloride. Through the self-polymerization reaction of dopamine hydrochloride, a polydopamine layer is formed on the surface of soft magnetic amorphous powder, which effectively improves the uniformity of the insulating coating layer, further reduces the magnetic loss of the prepared soft magnetic powder core, and improves the high frequency stability. Detailed Implementation

[0060] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0061] Example 1

[0062] This embodiment provides a soft magnetic powder core with a median particle size of 35 μm. The soft magnetic powder core includes soft magnetic amorphous powder (Fe). 73 Si 11 B 11 The magnetic core consists of a C3Cr2 layer and a polydopamine / polyacryl alcohol layer, with the polydopamine / polyacryl alcohol layer accounting for 0.04% of the mass of the soft magnetic powder core. The mass ratio of polydopamine to polyacryl alcohol is 7:3.

[0063] The method for preparing the soft magnetic powder core includes:

[0064] (1) Mix the pretreated soft magnetic amorphous powder with an insulating coating material solution with pH 8. The insulating coating material solution is a Tris mixed solution of dopamine hydrochloride and polyacrylamide, with a concentration of 30 mg / mL and a ratio of 7:3. Heat in a water bath at 40°C for 24 hours to obtain coated soft magnetic amorphous powder.

[0065] (2) Mix the acetone solution of the coated soft magnetic amorphous powder and epoxy resin at a ratio of 50:1, stir until the acetone is completely evaporated, and then dry at 60°C for 5 hours to obtain the mixed powder.

[0066] (3) After the mixed powder is cold-pressed at a pressure of 1.8 GPa, it is annealed at 500°C for 1 hour in a nitrogen atmosphere to obtain the soft magnetic powder core.

[0067] The preprocessing method is as follows:

[0068] The soft magnetic amorphous powder raw material was immersed in acetone for ultrasonic cleaning for 10 min, and then washed with deionized water 4 times to obtain the cleaned powder. The cleaned powder was mixed with 0.5 mol / L NaOH solution and stirred for 30 min, and then washed with deionized water until neutral to obtain the alkaline-treated powder. The alkaline-treated powder was immersed in a polyacryl alcohol solution with a concentration of 50 mg / mL for 30 min and then removed to obtain the pretreated soft magnetic amorphous powder.

[0069] Example 2

[0070] This embodiment provides a soft magnetic powder core with a median particle size of 10 μm. The soft magnetic powder core includes soft magnetic amorphous powder (Fe). 73 Si 11 B 11 The magnetic core consists of a C3Cr2 layer and a polydopamine / polyacryl alcohol layer, with the polydopamine / polyacryl alcohol layer accounting for 0.03% of the mass of the soft magnetic powder core. The mass ratio of polydopamine to polyacryl alcohol is 6:4.

[0071] The method for preparing the soft magnetic powder core includes:

[0072] (1) Mix the pretreated soft magnetic amorphous powder with an insulating coating material solution with a pH of 7.5. The insulating coating material solution is a Tris mixed solution of dopamine hydrochloride and polyacrylamide, with a concentration of 12 mg / mL and a ratio of 6:4. Heat in a water bath at 30°C for 48 hours to obtain coated soft magnetic amorphous powder.

[0073] (2) Mix the acetone solution of the coated soft magnetic amorphous powder and epoxy resin at a ratio of 50:1, stir until the acetone is completely evaporated, and then dry at 40°C for 6 hours to obtain the mixed powder.

[0074] (3) After the mixed powder is cold-pressed at a pressure of 1.2 GPa, it is annealed at 300°C for 0.5 h in a nitrogen atmosphere to obtain the soft magnetic powder core.

[0075] The preprocessing method is as follows:

[0076] The soft magnetic amorphous powder raw material was immersed in acetone for ultrasonic cleaning for 5 minutes, and then washed three times with deionized water to obtain the cleaned powder. The cleaned powder was mixed with 0.2 mol / L NaOH solution and stirred for 60 minutes, and then washed with deionized water until neutral to obtain the alkaline-treated powder. The alkaline-treated powder was immersed in a polyacryl alcohol solution with a concentration of 30 mg / mL for 60 minutes and then removed to obtain the pretreated soft magnetic amorphous powder.

[0077] Example 3

[0078] This embodiment provides a soft magnetic powder core with a median particle size of 60 μm. The soft magnetic powder core includes soft magnetic amorphous powder (Fe). 73 Si 11 B 11 The core consists of a C3Cr2 layer and a polydopamine / polyacryl alcohol layer, with the polydopamine / polyacryl alcohol layer accounting for 0.052% of the mass of the soft magnetic powder core. The mass ratio of polydopamine to polyacryl alcohol is 3:9.

[0079] The method for preparing the soft magnetic powder core includes:

[0080] (1) Mix the pretreated soft magnetic amorphous powder with an insulating coating material solution with a pH of 7.5. The insulating coating material solution is a Tris mixed solution of dopamine hydrochloride and polyacrylamide, with a concentration of 6 mg / mL and a ratio of 3:9. Heat in a water bath at 30°C for 48 hours to obtain coated soft magnetic amorphous powder.

[0081] (2) Mix the acetone solution of the coated soft magnetic amorphous powder and epoxy resin in a ratio of 40:1, stir until the acetone is completely evaporated, and then dry at 40°C for 6 hours to obtain the mixed powder.

[0082] (3) After the mixed powder is cold-pressed at a pressure of 1.2 GPa, it is annealed at 300°C for 2 hours in a nitrogen atmosphere to obtain the soft magnetic powder core.

[0083] The preprocessing method is as follows:

[0084] The soft magnetic amorphous powder raw material was immersed in acetone for ultrasonic cleaning for 5 minutes, and then washed three times with deionized water to obtain the cleaned powder. The cleaned powder was mixed with 0.2 mol / L NaOH solution and stirred for 60 minutes, and then washed with deionized water until neutral to obtain the alkaline-treated powder. The alkaline-treated powder was immersed in a polyacryl alcohol solution with a concentration of 30 mg / mL for 60 minutes and then removed to obtain the pretreated soft magnetic amorphous powder.

[0085] Example 4

[0086] This embodiment provides a soft magnetic powder core with a median particle size of 35 μm. The soft magnetic powder core includes soft magnetic amorphous powder (Fe). 73 Si 11 B 11 The magnetic core consists of a C3Cr2 layer and a polydopamine / polyacryl alcohol layer, with the polydopamine / polyacryl alcohol layer accounting for 0.04% of the mass of the soft magnetic powder core. The mass ratio of polydopamine to polyacryl alcohol is 8:2.

[0087] The method for preparing the soft magnetic powder core includes:

[0088] (1) Mix the pretreated soft magnetic amorphous powder with an insulating coating material solution with a pH of 8.5. The insulating coating material solution is a Tris mixed solution of dopamine hydrochloride and polyacrylamide, with a concentration of 35 mg / mL and a ratio of 8:2. Heat in a water bath at 50°C for 20 hours to obtain coated soft magnetic amorphous powder.

[0089] (2) Mix the acetone solution of the coated soft magnetic amorphous powder and epoxy resin at a ratio of 70:1, stir until the acetone is completely evaporated, and then dry at 105°C for 3 hours to obtain the mixed powder.

[0090] (3) After the mixed powder is cold-pressed at a pressure of 3.6 GPa, it is annealed at 600°C for 1 hour in a nitrogen atmosphere to obtain the soft magnetic powder core.

[0091] The preprocessing method is as follows:

[0092] The soft magnetic amorphous powder raw material was immersed in acetone for ultrasonic cleaning for 15 min, and then washed with deionized water 5 times to obtain the cleaned powder. The cleaned powder was mixed with 0.8 mol / L NaOH solution and stirred for 20 min, and then washed with deionized water until neutral to obtain the alkaline-treated powder. The alkaline-treated powder was immersed in a polyacryl alcohol solution with a concentration of 80 mg / mL for 20 min and then removed to obtain the pretreated soft magnetic amorphous powder.

[0093] Example 5

[0094] This embodiment provides a soft magnetic powder core, which differs from Embodiment 1 in that the dopamine hydrochloride in step (1) is replaced with an equal mass of polydopamine.

[0095] Example 6

[0096] This embodiment provides a soft magnetic powder core, which differs from Embodiment 1 in that the concentrations of dopamine hydrochloride and polyacrylamide in step (1) are 5 mg / mL.

[0097] Example 7

[0098] This embodiment provides a soft magnetic powder core, which differs from Embodiment 1 in that the concentration of dopamine hydrochloride and polyacrylol in step (1) is 40 mg / mL.

[0099] Example 8

[0100] This embodiment provides a soft magnetic powder core, which differs from Embodiment 1 in that the ratio of dopamine hydrochloride and polyacrylamide in step (1) is 2:8.

[0101] Example 9

[0102] This embodiment provides a soft magnetic powder core, which differs from Embodiment 1 in that the ratio of dopamine hydrochloride and polyacrylamide in step (1) is 9:1.

[0103] Example 10

[0104] This embodiment provides a soft magnetic powder core, which differs from Embodiment 1 in that it does not undergo a pretreatment process.

[0105] Example 11

[0106] This embodiment provides a soft magnetic powder core, which differs from Embodiment 1 in that it does not undergo a pretreatment process of soaking in a polyacryl alcohol solution.

[0107] Example 12

[0108] This embodiment provides a soft magnetic powder core with a median particle size of 10 μm. The soft magnetic powder core includes soft magnetic amorphous powder (Fe). 50 Si 30 Al 20 The core consists of a polydopamine / polyacrylamide layer, the mass of which is 0.03% of the mass of the soft magnetic powder core, and the mass ratio of polydopamine to polyacrylamide is 6:4.

[0109] The method for preparing the soft magnetic powder core includes:

[0110] (1) Mix the pretreated soft magnetic amorphous powder with an insulating coating material solution with a pH of 7.5. The insulating coating material solution is a Tris mixed solution of dopamine hydrochloride and polyacrylamide, with a concentration of 12 mg / mL and a ratio of 6:4. Heat in a water bath at 30°C for 48 hours to obtain coated soft magnetic amorphous powder.

[0111] (2) Mix the acetone solution of the coated soft magnetic amorphous powder and epoxy resin at a ratio of 50:1, stir until the acetone is completely evaporated, and then dry at 40°C for 6 hours to obtain the mixed powder.

[0112] (3) After the mixed powder is cold-pressed at a pressure of 1.2 GPa, it is annealed at 300°C for 0.5 h in a nitrogen atmosphere to obtain the soft magnetic powder core.

[0113] The preprocessing method is as follows:

[0114] The soft magnetic amorphous powder raw material was immersed in acetone for ultrasonic cleaning for 5 minutes, and then washed three times with deionized water to obtain the cleaned powder. The cleaned powder was mixed with 0.2 mol / L NaOH solution and stirred for 60 minutes, and then washed with deionized water until neutral to obtain the alkaline-treated powder. The alkaline-treated powder was immersed in a polyacryl alcohol solution with a concentration of 30 mg / mL for 60 minutes and then removed to obtain the pretreated soft magnetic amorphous powder.

[0115] Comparative Example 1

[0116] This comparative example provides a soft magnetic powder core, the preparation method of which is obtained with reference to CN 114068123A.

[0117] Comparative Example 2

[0118] This comparative example provides a soft magnetic powder core, which differs from Example 1 in that it has a phosphate coating layer.

[0119] The soft magnetic powder cores obtained above were tested, and the test results are shown in Table 1.

[0120] Table 1

[0121]

[0122]

[0123] The following conclusions can be drawn from Table 1:

[0124] (1) As can be seen from Examples 1-4, 12 and Comparative Examples 1, 2, the polydopamine / polyacrylamide layer can be maintained at 2.0 GPa without peeling, and the soft magnetic powder core has good insulation performance and low loss, ensuring a core loss of 521.3 mw / cm at 100 MHz. 3 .

[0125] (2) A comparison of Example 5 and Example 1 shows that in the preparation method of the present invention, the raw material for polydopamine is dopamine hydrochloride. Through the self-polymerization reaction of dopamine hydrochloride, a polydopamine layer is formed on the surface of the soft magnetic amorphous powder, which effectively improves the uniformity of the insulating coating layer, further reduces the magnetic loss of the prepared soft magnetic powder core, and improves high-frequency stability. When other raw materials are used, the self-polymerization reaction cannot be achieved, thus affecting the stability and magnetic loss.

[0126] (3) As can be seen from the comparison between Examples 6 and 7 and Example 1, when the concentrations of dopamine hydrochloride and polyacrylamide are not within the preferred range of the present invention, it is difficult for dopamine hydrochloride and polyacrylamide to construct a three-dimensional network insulation structure, thereby failing to improve the uniformity of the insulation coating layer and further affecting the reduction of magnetic loss of the soft magnetic powder core.

[0127] (4) As can be seen from the comparison between Examples 8 and 9 and Example 1, when the ratio of dopamine hydrochloride and polyacrylamide is not within the preferred range of the present invention, it is difficult for dopamine hydrochloride and polyacrylamide to construct a three-dimensional network insulation structure, thereby failing to improve the uniformity of the insulation coating layer and further affecting the reduction of magnetic loss of the soft magnetic powder core.

[0128] (5) As can be seen from the comparison between Examples 10 and 11 and Example 1, the pretreatment process is beneficial for insulation coating. When no pretreatment is performed, especially when the step of soaking in polyacryl alcohol solution is not performed, the self-polymerization reaction of dopamine hydrochloride is not conducive to proceeding, thus failing to improve the uniformity of the insulation coating layer, and further affecting the reduction of magnetic loss of the soft magnetic powder core.

[0129] In summary, this invention coats the surface of soft magnetic amorphous powder with a polydopamine / polyacrylamide layer. The catechol groups of polydopamine interact with the surface of the soft magnetic amorphous powder, and its hydroxyl functional groups can form hydrogen bonds with the groups of polyacrylamide, thus constructing a three-dimensional network insulating coating structure. This improves the mechanical properties of the soft magnetic powder core surface, thereby enhancing the high-frequency stability of the soft magnetic powder core and effectively broadening the application of soft magnetic powder cores in the high-frequency field.

[0130] This invention illustrates the detailed process equipment and process flow through the above embodiments. However, this invention is not limited to the detailed process equipment and process flow described above, meaning that this invention does not necessarily depend on the detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, all fall within the protection scope and disclosure scope of this invention.

Claims

1. A soft magnetic powder core, characterized in that, The soft magnetic powder core includes soft magnetic amorphous powder and an insulating coating layer, wherein the insulating coating layer is a polydopamine / polyacrylamide layer; In the insulating coating layer, the mass ratio of polydopamine to polyacrylamide is (3~8):(2~7); The soft magnetic amorphous powder is a pretreated soft magnetic amorphous powder; the pretreatment method includes washing the soft magnetic amorphous powder raw material, then performing alkaline treatment, and then mixing it with a polyacryl alcohol solution to complete the pretreatment. The preparation method includes the following steps: (1) Mix soft magnetic amorphous powder and insulating coating material solution to obtain coated soft magnetic amorphous powder; (2) Mix the coated soft magnetic amorphous powder and epoxy resin to obtain a mixed powder; (3) The mixed powder is cold-pressed and then annealed to obtain the soft magnetic powder core; Wherein, the soft magnetic amorphous powder in step (1) is a pretreated soft magnetic amorphous powder; the pretreatment method includes: The soft magnetic amorphous powder raw material is cleaned, then subjected to alkaline treatment, and then mixed with polyacryl alcohol solution to complete the pretreatment. The insulating coating material solution in step (1) includes a mixed solution of dopamine hydrochloride and polyacryl alcohol; the mass ratio of dopamine hydrochloride and polyacryl alcohol is (3~8):(2~7).

2. The soft magnetic powder core according to claim 1, characterized in that, The soft magnetic amorphous powder includes any one or a combination of at least two of Fe-Si-B, FeNiPB, CoZr, ZrTiCuNi, or FeSiAl.

3. The soft magnetic powder core according to claim 1, characterized in that, The mass of the insulating coating layer is 0.03~0.052% of the mass of the soft magnetic powder core.

4. The soft magnetic powder core according to claim 1, characterized in that, The median particle size of the soft magnetic powder core is 10~60μm.

5. The method for preparing the soft magnetic powder core according to any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: (1) Mix soft magnetic amorphous powder and insulating coating material solution to obtain coated soft magnetic amorphous powder; (2) Mix the coated soft magnetic amorphous powder and epoxy resin to obtain a mixed powder; (3) The mixed powder is cold-pressed and then annealed to obtain the soft magnetic powder core; Wherein, the soft magnetic amorphous powder in step (1) is a pretreated soft magnetic amorphous powder; the pretreatment method includes: The soft magnetic amorphous powder raw material is cleaned, then subjected to alkaline treatment, and then mixed with polyacryl alcohol solution to complete the pretreatment. The insulating coating material solution in step (1) includes a mixed solution of dopamine hydrochloride and polyacryl alcohol; the mass ratio of dopamine hydrochloride and polyacryl alcohol is (3~8):(2~7).

6. The preparation method according to claim 5, characterized in that, The cleaning process includes ultrasonic cleaning in acetone solution and / or cleaning with deionized water.

7. The preparation method according to claim 6, characterized in that, The ultrasonic cleaning time in the acetone solution is 5-15 minutes.

8. The preparation method according to claim 5, characterized in that, The alkaline treatment includes mixing the washed powder and alkaline solution and stirring.

9. The preparation method according to claim 8, characterized in that, The alkaline solution comprises a 0.2-0.8 mol / L NaOH solution.

10. The preparation method according to claim 8, characterized in that, The stirring time is 20-60 minutes.

11. The preparation method according to claim 5, characterized in that, The concentration of the polyacrylol solution is 30~80 mg / mL.

12. The preparation method according to claim 5, characterized in that, In the insulating coating material solution, the concentrations of dopamine hydrochloride and polyacrylamide are 6~35 mg / mL.

13. The preparation method according to claim 5, characterized in that, The solvent for the insulating coating material solution is Tris solvent.

14. The preparation method according to claim 5, characterized in that, The pH of the insulating coating material solution is 7.5~8.

5.

15. The preparation method according to claim 5, characterized in that, Step (1) further includes heating after mixing.

16. The preparation method according to claim 15, characterized in that, The heating temperature is 30~50℃.

17. The preparation method according to claim 15, characterized in that, The heating time is 20~48h.

18. The preparation method according to claim 5, characterized in that, The epoxy resin mentioned in step (2) is an acetone solution of epoxy resin.

19. The preparation method according to claim 5, characterized in that, In step (2), the mass ratio of the coated soft magnetic amorphous powder and epoxy resin in the mixture is 40~70:

1.

20. The preparation method according to claim 5, characterized in that, The mixing in step (2) includes stirring.

21. The preparation method according to claim 20, characterized in that, Stir until the solvent has completely evaporated.

22. The preparation method according to claim 20, characterized in that, The mixing process also includes drying.

23. The preparation method according to claim 22, characterized in that, The drying temperature is 40~105℃.

24. The preparation method according to claim 22, characterized in that, The drying time is 3 to 6 hours.

25. The preparation method according to claim 5, characterized in that, The pressure for cold pressing in step (3) is 1.2~3.6 GPa.

26. The preparation method according to claim 5, characterized in that, The annealing process is performed in a protective atmosphere.

27. The preparation method according to claim 5, characterized in that, The annealing temperature is 300~600℃.

28. The preparation method according to claim 5, characterized in that, The annealing process takes 0.5 to 2 hours.

29. The preparation method according to claim 5, characterized in that, The preparation method includes the following steps: (1) Mix pretreated soft magnetic amorphous powder with an insulating coating material solution with a pH of 7.5~8.

5. The insulating coating material solution is a Tris mixed solution of dopamine hydrochloride and polyacrylamide, with a concentration of 6~35 mg / mL and a ratio of (3~8):(2~7). Heat in a water bath at 30~50℃ for 20~48h to obtain coated soft magnetic amorphous powder. (2) Mix the acetone solution of the coated soft magnetic amorphous powder and epoxy resin in a ratio of 40~70:1, stir until the acetone is completely evaporated, and then dry at 40~105℃ for 3~6h to obtain the mixed powder. (3) After the mixed powder is cold-pressed at a pressure of 1.2~3.6GPa, it is annealed at 300~600℃ for 0.5~2h in a protective atmosphere to obtain the soft magnetic powder core; The preprocessing method is as follows: The soft magnetic amorphous powder raw material is immersed in acetone for ultrasonic cleaning for 5-15 minutes, and then washed with deionized water 3-5 times to obtain the cleaned powder. The cleaned powder is mixed with 0.2-0.8 mol / L NaOH solution and stirred for 20-60 minutes, and then washed with deionized water until neutral to obtain the alkaline-treated powder. The alkaline-treated powder is immersed in a polyacryl alcohol solution with a concentration of 30-80 mg / mL for 20-60 minutes and then removed to obtain the pretreated soft magnetic amorphous powder.

30. An application of the soft magnetic powder core according to any one of claims 1 to 4, characterized in that, The soft magnetic powder core is used in inductors or power devices.

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