Low-loss FeSi-coated CIP composite soft magnetic powder core and preparation method thereof

Abstract

The invention relates to a low-loss FeSi-CIP composite soft magnetic powder core and a preparation method thereof. The adopted raw material powder is composed of amorphous nanocrystalline atomized FeSi series powder and filling powder composed of carbonyl iron powder and iron-silicon-aluminum powder. The carbonyl iron powder accounts for 15-25% of the mass of the raw material powder, the iron-silicon-aluminum powder accounts for 5-15% of the mass of the raw material powder, and the filling powder accounts for 25-35% of the mass of the raw material powder. Two-stage warm-pressing pressing is adopted, self-tempering is achieved to a certain extent at the specific warm-pressing temperature, and high direct-current bias performance and low iron loss can be obtained without heat treatment annealing after pressing forming. The effective magnetic conductivity of the powder core is 42 or above, the loss is as low as 350 mW / cm < 3 > (50 mT, 100 kHz), and the direct current bias performance under the external field of 100 Oe reaches 90% or above.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, and particularly relates to a low-loss FeSi@CIP composite soft magnetic powder core and its preparation method. Background Technology

[0002] In recent years, the demand for metal magnetic powder cores has grown rapidly due to the development of new energy vehicles, charging piles, photovoltaic energy storage, and other fields. Furthermore, the penetration rate of magnetic powder cores in data centers, power quality management, consumer electronics, and servers is also gradually increasing. With continuous breakthroughs in magnetic powder core technology and the ongoing expansion of application scenarios across different frequency bands, the market potential is significant. In the data center field, metal magnetic powder core products are mainly used in uninterruptible power supplies (UPS), communication power supplies, and server power supplies, achieving functions such as energy storage, filtering, and voltage stabilization. With the development of next-generation digital technologies such as 5G, artificial intelligence, and cloud computing, data centers, as data hubs and computing power carriers, are experiencing sustainable development, inevitably driving the continued growth in demand for servers and related high-power electrical equipment (UPS, communication power supplies, server power supplies).

[0003] Active power filters (APFs) are a new type of power electronic device used for dynamically suppressing harmonics and compensating for reactive power. They can compensate for varying harmonics (magnitude and frequency) and reactive power. Employing low-loss, high-DC-bias alloy soft magnetic materials can significantly reduce energy loss during APF operation, improve its operating efficiency, lower manufacturing costs, and enhance its market competitiveness. Current technologies commonly use FeSi soft magnetic materials, often combined with carbonyl iron powder (CIP) to improve performance.

[0004] However, existing FeSi soft magnetic materials have low DC bias performance and high losses. There is an urgent need to develop a soft magnetic material with high DC bias and low loss to meet market requirements and drive industry development. Summary of the Invention

[0005] This invention provides a low-loss FeSi@CIP composite soft magnetic powder core and its preparation method, addressing the problems of low DC bias performance and high loss in current FeSi soft magnetic materials. The resulting low-loss FeSi@CIP composite soft magnetic powder core exhibits a permeability above 42 and a core loss as low as 350 mW / cm². 3 It has a DC bias performance of over 90% under a 100 Oe field and excellent soft magnetic properties.

[0006] In a first aspect, the present invention relates to a low-loss FeSi@CIP composite soft magnetic powder core, which is composed of amorphous nanocrystalline atomized FeSi powder as raw material powder, and a filler powder composed of carbonyl iron powder and iron-silicon-aluminum powder.

[0007] The amorphous nanocrystalline atomized FeSi-based powder composition contains, by mass percentage, 11-12% Si, 7-8% B, 1.2-1.3% C, 2.0-2.2% Cr, 0.5-0.6% Mn, 0.03-0.05% Al, with the balance being Fe;

[0008] The iron-silicon-aluminum powder composition, by mass percentage, contains 5-7% Si, 4-7% Al, 0.3-0.5% C, 1.3-1.5% P, with the balance being Fe;

[0009] The carbonyl iron powder contains, by mass percentage: N≤0.008%, O≤0.6%, C≤0.02%, with the balance being Fe;

[0010] The carbonyl iron powder accounts for 15-25% of the raw material powder by mass, the iron-silicon-aluminum powder accounts for 5-15% of the raw material powder by mass, and the filler powder accounts for 25-35% of the raw material powder by mass.

[0011] Preferably, the filler powder accounts for 27-32% of the mass of the raw material powder.

[0012] Preferably, the amorphous nanocrystalline atomized FeSi powder has a particle size of 25–35 μm.

[0013] The carbonyl iron powder has a particle size of 12–16 μm, and the iron-silicon-aluminum powder has a particle size of 15–25 μm.

[0014] Secondly, the present invention relates to a method for preparing a low-loss FeSi@CIP composite soft magnetic powder core, comprising the following steps:

[0015] (1) Powder pretreatment: Amorphous nanocrystalline atomized FeSi powder and iron-silicon-aluminum powder are pre-calcined at 350 ℃~400 ℃ in a hydrogen atmosphere;

[0016] (2) Mixing raw materials: The amorphous nanocrystalline atomized FeSi powder obtained in step (1), iron-silicon-aluminum powder, and carbonyl iron powder are mixed evenly in proportion to obtain a mixed powder.

[0017] (3) Passivation: The mixed powder is subjected to phosphoric acid passivation treatment;

[0018] (4) Insulation coating treatment: The acetone solution of epoxy resin and phenolic amine epoxy curing agent is uniformly stirred to achieve insulation coating of the mixed powder. After drying, the mixed powder required for temperature pressing is obtained.

[0019] (5) Warm pressing: Weigh an appropriate amount of the mixed powder obtained in step (4), heat it to the warm pressing temperature and put it into the preheated warm pressing mold for pressing. The pressing temperature is 180 ℃~300 ℃. In the first stage, press at 500 MPa~600 MPa for 2~6 min. In the second stage, press at 1000 MPa~1200 MPa for 3~5 min. After pressing, a low-loss FeSi@CIP composite soft magnetic powder core is obtained.

[0020] Preferably, the passivation is performed using a phosphoric acid passivation solution composed of a mixture of acetone and phosphoric acid.

[0021] Preferably, the drying in step (4) is carried out at 80 ℃~100 ℃ for 1~2 h.

[0022] Preferably, in step (5), the first stage is pressure-pressed at 530 MPa, and the second stage is pressure-pressed at 1050 MPa.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention uses composite powder as the main component, which is amorphous nanocrystalline atomized FeSi-based powder, combined with carbonyl iron powder and iron-silicon-aluminum powder. The FeSi alloy with specific components has relatively high resistivity and saturation magnetization density, while the carbonyl iron powder has small particle size and good DC superposition characteristics. When combined with the iron-silicon-chromium alloy powder, the three different powder components work together to comprehensively improve the DC bias performance of the iron-silicon powder core and reduce losses.

[0025] By selecting small-particle-size iron-silicon-chromium alloy powder and even smaller-particle-size carbonyl iron powder, and mixing them with large-particle-size amorphous nanocrystalline atomized FeSi-based powder, specific sizes of coarse and fine powders can be used to achieve efficient filling, increase density, improve magnetic core density, optimize magnetic core magnetism, and thus significantly reduce product power loss.

[0026] Pre-treating amorphous nanocrystalline FeSi-based powder and iron-silicon-aluminum powder can effectively eliminate residual stress during the powder atomization process, improve powder performance, enhance thermal stability, optimize the internal structure of particles, eliminate magnetic domain walls of amorphous particles, and thus improve the DC bias performance of iron-silicon magnetic rings.

[0027] Selecting a specific temperature for thermoforming allows for the achievement of the desired curing effect. Furthermore, this invention employs a two-stage thermoforming process. In the first stage, at 500 MPa to 600 MPa, the powder exhibits high porosity, and the coating material retains a certain degree of fluidity, enabling large particle displacement deformation and promoting densification. In the second stage, at 1000 MPa to 1200 MPa, the particles undergo plastic deformation. The increased pressure further reduces the gaps between powder particles, increasing the filling coefficient, density, and reducing eddy current losses.

[0028] Warm-pressing employs a two-stage pressing process, achieving a certain degree of self-tempering under specific temperature and pressure conditions. After pressing, no heat treatment annealing is required to obtain the magnetic ring with high DC bias performance and low iron loss. The powder core achieves an effective permeability of over 42 and a loss as low as 350 mW / cm. 3 (50 mT / 100 kHz), DC bias performance is over 90% (100 Oe field). Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of a low-loss FeSi@CIP composite soft magnetic powder core preparation process disclosed in an embodiment of the present invention. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0032] Existing FeSi soft magnetic materials have low DC bias performance and high loss, so there is an urgent need to develop a soft magnetic material with high DC bias and low loss to meet market requirements and promote industry development.

[0033] To address the aforementioned technical problems, this invention provides a low-loss FeSi@CIP composite soft magnetic powder core, which is composed of amorphous nanocrystalline atomized FeSi powder as raw material, and a filler powder composed of carbonyl iron powder and iron-silicon-aluminum powder.

[0034] The amorphous nanocrystalline atomized FeSi-based powder composition contains, by mass percentage, 11-12% Si, 7-8% B, 1.2-1.3% C, 2.0-2.2% Cr, 0.5-0.6% Mn, 0.03-0.05% Al, with the balance being Fe;

[0035] The iron-silicon-aluminum powder composition, by mass percentage, contains 5-7% Si, 4-7% Al, 0.3-0.5% C, 1.3-1.5% P, with the balance being Fe;

[0036] The carbonyl iron powder contains, by mass percentage: N≤0.008%, O≤0.6%, C≤0.02%, with the balance being Fe;

[0037] The carbonyl iron powder accounts for 15-25% of the raw material powder by mass, the iron-silicon-aluminum powder accounts for 5-15% of the raw material powder by mass, and the filler powder accounts for 25-35% of the raw material powder by mass.

[0038] In one embodiment, the filler powder is added at a mass ratio of 27% to 32% of the raw material powder.

[0039] In one embodiment, the amorphous nanocrystalline atomized FeSi powder has a particle size of 25–35 μm.

[0040] The carbonyl iron powder has a particle size of 12–16 μm, and the iron-silicon-aluminum powder has a particle size of 15–25 μm.

[0041] The composite powder is mainly composed of amorphous and nanocrystalline atomized FeSi-based powder, supplemented with carbonyl iron powder and iron-silicon-aluminum powder. The FeSi alloy exhibits relatively high resistivity and saturation magnetization, with a preferred silicon content of 11–12%. Adding 1.2–1.3% C, 2.0–2.2% Cr, 0.5–0.6% Mn, and 0.03–0.05% Al can further improve its saturation magnetization. The amorphous and nanocrystalline atomized FeSi-based powder has high hardness and near-spherical shape, making it difficult to compress during the compaction process. Therefore, it contains numerous pores between particles, requiring more forming agent and higher pressure. Carbonyl iron powder has a small particle size, is easy to press and form, and its Ms is as high as 200 emu / g, which can effectively improve the overall Bs value of the powder core and has good DC superposition characteristics; the preferred composition of iron-silicon-chromium alloy powder is Si 5-7%, Al 4-7%, C 0.3-0.5%, P 1.3-1.5%, with the balance being Fe, which has excellent resistivity and saturation magnetization density.

[0042] By selecting iron-silicon-aluminum powder with a particle size of 15–25 μm, carbonyl iron powder with a particle size of 12–16 μm, and using small-particle-size iron-silicon-chromium alloy powder and even smaller-particle-size carbonyl iron powder with large-particle-size amorphous nanocrystalline atomized FeSi-based powder, a mixture of coarse and fine powders of specific sizes is achieved. This results in efficient filling, increased density, improved magnetic core density, and optimized magnetic core magnetism, thereby significantly reducing product power loss. To achieve the above effects, the carbonyl iron powder accounts for 15–25% of the raw material powder by mass, and the iron-silicon-aluminum powder accounts for 5–15% of the raw material powder by mass. The study also found that when the carbonyl iron powder and iron-silicon-aluminum powder filler powder accounts for 25–35% of the raw material powder by mass, even better DC bias performance and loss of the iron-silicon magnetic ring can be achieved.

[0043] like Figure 1As shown, an embodiment of the present invention provides a method for preparing a low-loss FeSi@CIP composite soft magnetic powder core, comprising the following steps:

[0044] (1) Powder pretreatment: Amorphous nanocrystalline atomized FeSi powder and iron-silicon-aluminum powder are pre-calcined at 350℃~400℃ in a hydrogen atmosphere.

[0045] (2) Mixing raw materials: The amorphous nanocrystalline atomized FeSi powder obtained in step (1), iron-silicon-aluminum powder, and carbonyl iron powder are mixed evenly in proportion to obtain a mixed powder.

[0046] (3) Passivation: The mixed powder is subjected to phosphoric acid passivation treatment;

[0047] (4) Insulation coating treatment: The acetone solution of epoxy resin and phenolic amine epoxy curing agent is uniformly stirred to achieve insulation coating of the mixed powder. After drying, the mixed powder required for temperature pressing is obtained.

[0048] (5) Warm pressing: Weigh an appropriate amount of the mixed powder obtained in step (4), heat it to the warm pressing temperature and put it into the preheated warm pressing mold for pressing. The pressing temperature is 180 ℃~300 ℃. In the first stage, the pressure is 500 MPa~600 MPa for 2~6 min. In the second stage, the pressure is 1000 MPa~1200 MPa for 3~5 min. After pressing, a low-loss FeSi@CIP composite soft magnetic powder core is obtained.

[0049] Amorphous nanocrystalline FeSi powder and iron-silicon-aluminum powder are obtained by ultra-rapid solidification atomization. However, some residual stress still exists inside. Pre-treating the two powders at 350℃~400℃ can effectively eliminate the residual stress in the atomization process, improve the powder performance, enhance thermal stability, optimize the internal structure of the particles, eliminate the magnetic domain walls of amorphous particles, and thus improve the DC bias performance of iron-silicon magnetic rings.

[0050] Warm pressing simultaneously densifies and cures the resin by heating the mold to the required curing temperature and applying a certain pressing force. The selection of the warm pressing temperature in this invention considers both the curing effect and the two-stage warm pressing process. In the first stage, at 500 MPa to 600 MPa, the powder has high porosity, and the coating material still possesses a certain degree of fluidity, allowing for large particle displacement deformation and promoting densification. In the second stage, at 1000 MPa to 1200 MPa, the particles undergo plastic deformation, and the increased pressing pressure further reduces powder porosity, increasing the filling coefficient and density while reducing eddy current losses. Furthermore, the two-stage pressing process, with its stepwise increase in pressure, weakens the generation of internal stress in the powder, and the warm pressing within the 180℃ to 300℃ range allows for a degree of self-tempering, further eliminating some residual stress. Therefore, high DC bias performance and low iron loss of the magnetic ring can be obtained without heat treatment annealing after pressing. The resulting powder core has an effective magnetic permeability of over 42 and a loss as low as 350 mW / cm. 3 (50 mT / 100 kHz), DC bias performance is over 90% (100 Oe field).

[0051] In one embodiment, the passivation uses a phosphoric acid passivation solution composed of a mixture of acetone and phosphoric acid.

[0052] In one embodiment, step (4) drying is performed at 80 ℃ to 100 ℃ for 1 to 2 h.

[0053] In one embodiment, step (5) involves pressing at 530 MPa in the first stage and at 1050 MPa in the second stage.

[0054] Example 1:

[0055] A method for preparing a low-loss FeSi@CIP composite soft magnetic powder core, wherein the raw material powder is composed of amorphous nanocrystalline atomized FeSi powder, and filler powder composed of carbonyl iron powder and iron-silicon-aluminum powder;

[0056] The amorphous nanocrystalline atomized FeSi-based powder composition contains, by mass percentage, 11% Si, 7% B, 1.3% C, 2.0% Cr, 0.5% Mn, 0.03% Al, with the balance being Fe;

[0057] The iron-silicon-aluminum powder composition, by mass percentage, contains 7% Si, 7% Al, 0.5% C, 1.3% P, with the balance being Fe;

[0058] The carbonyl iron powder contains, by mass percentage: N≤0.006%, O≤0.4%, C≤0.01%, with the balance being Fe;

[0059] The carbonyl iron powder accounts for 15% of the raw material powder by mass, the iron-silicon-aluminum powder accounts for 12% of the raw material powder by mass, and the filler powder accounts for 27% of the raw material powder by mass.

[0060] The amorphous nanocrystalline atomized FeSi powder has a particle size of 25 μm, the carbonyl iron powder has a particle size of 15 μm, and the iron-silicon-aluminum powder has a particle size of 12 μm.

[0061] Includes the following steps:

[0062] (1) Powder pretreatment: Amorphous nanocrystalline atomized FeSi powder and iron-silicon-aluminum powder are pre-calcined at 360°C in a hydrogen atmosphere.

[0063] (2) Mixing raw materials: The amorphous nanocrystalline atomized FeSi powder obtained in step (1), iron-silicon-aluminum powder, and carbonyl iron powder are mixed evenly in proportion to obtain a mixed powder.

[0064] (3) Passivation: The mixed powder is subjected to phosphoric acid passivation treatment using a phosphoric acid passivation solution made of acetone and phosphoric acid;

[0065] (4) Insulation coating treatment: The acetone solution of epoxy resin and phenolic amine epoxy curing agent is uniformly stirred to achieve insulation coating of the mixed powder. After drying at 80 ℃ for 2 h, the mixed powder required for temperature pressing is obtained.

[0066] (5) Warm pressing: Weigh an appropriate amount of the mixed powder obtained in step (4), heat it to the warm pressing temperature and put it into the preheated warm pressing mold for pressing. The pressing temperature is 190 ℃. In the first stage, press at 510 MPa for 6 min and in the second stage, press at 1100 MPa for 3 min. After pressing, a low-loss FeSi@CIP composite soft magnetic powder core is obtained.

[0067] Example 2:

[0068] A method for preparing a low-loss FeSi@CIP composite soft magnetic powder core, wherein the raw material powder is composed of amorphous nanocrystalline atomized FeSi powder, and filler powder composed of carbonyl iron powder and iron-silicon-aluminum powder;

[0069] The amorphous nanocrystalline atomized FeSi-based powder composition, by mass percentage, contains 11.5% Si, 7.5% B, 1.3% C, 2.1% Cr, 0.5% Mn, 0.04% Al, with the balance being Fe;

[0070] The iron-silicon-aluminum powder composition, by mass percentage, contains 5% Si, 6% Al, 0.4% C, 1.4% P, with the balance being Fe;

[0071] The carbonyl iron powder contains, by mass percentage: N≤0.006%, O≤0.4%, C≤0.01%, with the balance being Fe;

[0072] The carbonyl iron powder accounts for 18% of the raw material powder by mass, the iron-silicon-aluminum powder accounts for 14% of the raw material powder by mass, and the filler powder accounts for 32% of the raw material powder by mass.

[0073] The amorphous nanocrystalline atomized FeSi-based powder has a particle size of 24 μm, the carbonyl iron powder has a particle size of 13 μm, and the iron-silicon-aluminum powder has a particle size of 14 μm.

[0074] Includes the following steps:

[0075] (1) Powder pretreatment: Amorphous nanocrystalline atomized FeSi powder and iron-silicon-aluminum powder are pre-calcined at 370 °C in a hydrogen atmosphere;

[0076] (2) Mixing raw materials: The amorphous nanocrystalline atomized FeSi powder obtained in step (1), iron-silicon-aluminum powder, and carbonyl iron powder are mixed evenly in proportion to obtain a mixed powder.

[0077] (3) Passivation: The mixed powder is subjected to phosphoric acid passivation treatment using a phosphoric acid passivation solution made of acetone and phosphoric acid;

[0078] (4) Insulation coating treatment: The acetone solution of epoxy resin and phenolic amine epoxy curing agent is uniformly stirred to achieve insulation coating of the mixed powder. After drying at 90 ℃ for 1.5 h, the mixed powder required for temperature pressing is obtained.

[0079] (5) Warm pressing: Weigh an appropriate amount of the mixed powder obtained in step (4), heat it to the warm pressing temperature and put it into the preheated warm pressing mold for pressing. The pressing temperature is 250 ℃. In the first stage, the pressure is 530 MPa for 4 min, and in the second stage, the pressure is 1050 MPa for 4 min. After pressing, a low-loss FeSi@CIP composite soft magnetic powder core is obtained.

[0080] Example 3:

[0081] A method for preparing a low-loss FeSi@CIP composite soft magnetic powder core, wherein the raw material powder is composed of amorphous nanocrystalline atomized FeSi powder, and filler powder composed of carbonyl iron powder and iron-silicon-aluminum powder;

[0082] The amorphous nanocrystalline atomized FeSi-based powder composition contains, by mass percentage, 12% Si, 8% B, 1.2% C, 2.2% Cr, 0.6% Mn, 0.05% Al, with the balance being Fe;

[0083] The iron-silicon-aluminum powder composition, by mass percentage, contains 6% Si, 4% Al, 0.3% C, 1.5% P, with the balance being Fe;

[0084] The carbonyl iron powder contains, by mass percentage: N≤0.006%, O≤0.4%, C≤0.01%, with the balance being Fe;

[0085] The carbonyl iron powder accounts for 25% of the raw material powder by mass, the iron-silicon-aluminum powder accounts for 5% of the raw material powder by mass, and the filler powder accounts for 30% of the raw material powder by mass.

[0086] The amorphous nanocrystalline atomized FeSi-based powder has a particle size of 30 μm, the carbonyl iron powder has a particle size of 25 μm, and the iron-silicon-aluminum powder has a particle size of 5 μm.

[0087] Includes the following steps:

[0088] (1) Powder pretreatment: Amorphous nanocrystalline atomized FeSi powder and iron-silicon-aluminum powder are pre-calcined at 350°C in a hydrogen atmosphere.

[0089] (2) Mixing raw materials: The amorphous nanocrystalline atomized FeSi powder obtained in step (1), iron-silicon-aluminum powder, and carbonyl iron powder are mixed evenly in proportion to obtain a mixed powder.

[0090] (3) Passivation: The mixed powder is subjected to phosphoric acid passivation treatment using a phosphoric acid passivation solution made of acetone and phosphoric acid;

[0091] (4) Insulation coating treatment: The acetone solution of epoxy resin and phenolic amine epoxy curing agent is uniformly stirred to achieve insulation coating of the mixed powder. After drying at 100 ℃ for 1 h, the mixed powder required for temperature pressing is obtained.

[0092] (5) Warm pressing: Weigh an appropriate amount of the mixed powder obtained in step (4), heat it to the warm pressing temperature and put it into the preheated warm pressing mold for pressing. The pressing temperature is 300 ℃. In the first stage, press at 500 MPa for 2 min and in the second stage, press at 1000 MPa for 5 min. After pressing, a low-loss FeSi@CIP composite soft magnetic powder core is obtained.

[0093] Example 4:

[0094] A method for preparing a low-loss FeSi@CIP composite soft magnetic powder core, wherein the raw material powder is composed of amorphous nanocrystalline atomized FeSi powder, and filler powder composed of carbonyl iron powder and iron-silicon-aluminum powder;

[0095] The amorphous nanocrystalline atomized FeSi-based powder composition contains, by mass percentage, 11% Si, 8% B, 1.3% C, 2.0% Cr, 0.5% Mn, 0.04% Al, with the balance being Fe;

[0096] The iron-silicon-aluminum powder composition, by mass percentage, contains 7% Si, 6% Al, 0.5% C, 1.3% P, with the balance being Fe;

[0097] The carbonyl iron powder contains, by mass percentage: N≤0.006%, O≤0.4%, C≤0.01%, with the balance being Fe;

[0098] The carbonyl iron powder accounts for 20% of the raw material powder by mass, the iron-silicon-aluminum powder accounts for 8% of the raw material powder by mass, and the filler powder accounts for 28% of the raw material powder by mass.

[0099] The amorphous nanocrystalline atomized FeSi powder has a particle size of 35 μm, the carbonyl iron powder has a particle size of 16 μm, and the iron-silicon-aluminum powder has a particle size of 25 μm.

[0100] Includes the following steps:

[0101] (1) Powder pretreatment: Amorphous nanocrystalline atomized FeSi powder and iron-silicon-aluminum powder are pre-calcined at 400°C in a hydrogen atmosphere.

[0102] (2) Mixing raw materials: The amorphous nanocrystalline atomized FeSi powder obtained in step (1), iron-silicon-aluminum powder, and carbonyl iron powder are mixed evenly in proportion to obtain a mixed powder.

[0103] (3) Passivation: The mixed powder is subjected to phosphoric acid passivation treatment using a phosphoric acid passivation solution made of acetone and phosphoric acid;

[0104] (4) Insulation coating treatment: The acetone solution of epoxy resin and phenolic amine epoxy curing agent is uniformly stirred to achieve insulation coating of the mixed powder. After drying at 80 ℃ for 2 h, the mixed powder required for temperature pressing is obtained.

[0105] (5) Warm pressing: Weigh an appropriate amount of the mixed powder obtained in step (4), heat it to the warm pressing temperature and put it into the preheated warm pressing mold for pressing. The pressing temperature is 180 ℃. In the first stage, press at 600 MPa for 3 min and in the second stage, press at 1200 MPa for 4 min. After pressing, a low-loss FeSi@CIP composite soft magnetic powder core is obtained.

[0106] Comparative Example 1

[0107] The difference between the preparation method of the low-loss FeSi@CIP composite soft magnetic powder core in Comparative Example 1 and Example 2 is only that: the amorphous nanocrystalline atomized FeSi powder composition contains, by mass percentage, 10% Si, 5% B, 1.0% C, 3% Cr, 0.5% Mn, 0.04% Al, with the balance being Fe;

[0108] The iron-silicon-aluminum powder composition, by mass percentage, contains 4% Si, 3% Al, 0.2% C, 1.4% P, with the balance being Fe.

[0109] Comparative Example 2

[0110] The preparation method of the low-loss FeSi@CIP composite soft magnetic powder core in Comparative Example 2 differs from that in Example 2 only in that: the carbonyl iron powder accounts for 13% of the raw material powder by mass, the iron-silicon-aluminum powder accounts for 5% of the raw material powder by mass, and the filler powder accounts for 18% of the raw material powder by mass.

[0111] Comparative Example 3

[0112] The preparation method of the low-loss FeSi@CIP composite soft magnetic powder core in Comparative Example 3 differs from that in Example 2 only in that: the carbonyl iron powder accounts for 27% of the raw material powder by mass, the iron-silicon-aluminum powder accounts for 16% of the raw material powder by mass, and the filler powder accounts for 43% of the raw material powder by mass.

[0113] Comparative Example 4

[0114] The preparation method of the low-loss FeSi@CIP composite soft magnetic powder core in Comparative Example 4 differs from that in Example 2 only in that: the amorphous nanocrystalline atomized FeSi powder has a particle size of 40 μm, the carbonyl iron powder has a particle size of 25 μm, and the iron-silicon-aluminum powder has a particle size of 30 μm.

[0115] Comparative Example 5

[0116] The difference between the preparation method of the low-loss FeSi@CIP composite soft magnetic powder core in Comparative Example 5 and Example 2 is only that: (1) Powder pretreatment: amorphous nanocrystalline atomized FeSi powder and iron-silicon-aluminum powder are pre-calcined at 300°C in a hydrogen atmosphere.

[0117] Comparative Example 6

[0118] The preparation method of the low-loss FeSi@CIP composite soft magnetic powder core in Comparative Example 6 differs from that in Example 2 only in the following aspects: warm pressing: weigh an appropriate amount of the mixed powder obtained in step (4), heat it to the warm pressing temperature and put it into a preheated warm pressing mold for pressing. The pressing temperature is 150 ℃. In the first stage, the pressure is 300 MPa for 4 min, and in the second stage, the pressure is 800 MPa for 4 min. After pressing, the low-loss FeSi@CIP composite soft magnetic powder core is obtained.

[0119] Comparative Example 7

[0120] The difference between the preparation method of the low-loss FeSi@CIP composite soft magnetic powder core in Comparative Example 7 and Example 2 is only that: warm pressing: weigh an appropriate amount of the mixed powder obtained in step (4), heat it to the warm pressing temperature and put it into a preheated warm pressing mold for pressing. The pressing temperature is 150 ℃, and it is pressed at 1000 MPa pressure for 4 min. After pressing, the low-loss FeSi@CIP composite soft magnetic powder core is obtained.

[0121] The low-loss FeSi@CIP composite soft magnetic powder cores prepared in Examples 1-4 and Comparative Examples 1-7 were used to wind coils. The magnetic permeability was calculated by testing the magnetic ring inductance. The power loss of the magnetic ring at 50mT and 100kHz, and its DC bias performance under an external field of 100 Oe were also tested. The results are shown in Table 1.

[0122] Table 1: Performance data of soft magnetic powder cores prepared in the examples and comparative examples

[0123] <![CDATA[Effective permeability μ e > <![CDATA[Core loss (mW / cm 3 ).]]> DC bias performance (%) Example 1 42 380 90 Example 2 50 350 94 Example 3 45 361 91 Example 4 48 357 92 Comparative Example 1 33 445 70 Comparative Example 2 35 450 61 Comparative Example 3 36 462 65 Comparative Example 4 35 432 69 Comparative Example 5 34 489 53 Comparative Example 6 37 478 59 Comparative Example 7 32 501 56

[0124] Table 1 shows that the low-loss FeSi@CIP composite soft magnetic powder core prepared by this invention has a permeability of over 42 and a core loss as low as 350 mW / cm. 3 The DC bias performance is as high as 90% or more (100 Oe external field). The prepared composite soft magnetic powder core has low loss, high permeability and excellent DC bias performance, and has excellent overall soft magnetic properties.

[0125] Compared with Comparative Examples 1 to 3, after adjusting the raw material composition and ratio, amorphous nanocrystalline atomized FeSi-based powder, carbonyl iron powder, and iron-silicon-aluminum powder could not achieve synergy, and could not improve the DC bias performance of the iron-silicon powder core and reduce losses, resulting in a sharp decrease in core loss and permeability, and a significant reduction in DC bias performance.

[0126] Comparative Example 4: Adjusting the particle size of amorphous nanocrystalline atomized FeSi-based powder, carbonyl iron powder, and iron-silicon-aluminum powder failed to achieve efficient filling, increase density, improve magnetic powder core density, and optimize magnetic powder core magnetism. This resulted in a sharp decrease in magnetic core loss and permeability, and a significant reduction in DC bias performance.

[0127] Comparative Examples 5-7 adjusted the preparation method. After changing the pretreatment temperature and the warm pressing method, it was impossible to effectively eliminate the residual stress of the powder during the atomization process, nor could it achieve self-tempering during the warm pressing process, thus failing to achieve high DC bias performance and low iron loss of the magnetic ring without heat treatment annealing after pressing. This resulted in a sharp decrease in core loss and permeability, and a significant reduction in DC bias performance.

[0128] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in these combinations of technical features, they should be considered to be within the scope of this specification.

Claims

1. A low-loss FeSi@CIP composite soft magnetic powder core, characterized in that, The raw material powder used consists of amorphous nanocrystalline atomized FeSi-based powder, as well as filler powder composed of carbonyl iron powder and iron-silicon-aluminum powder; The amorphous nanocrystalline atomized FeSi-based powder composition contains, by mass percentage, 11-12% Si, 7-8% B, 1.2-1.3% C, 2.0-2.2% Cr, 0.5-0.6% Mn, 0.03-0.05% Al, with the balance being Fe; The iron-silicon-aluminum powder composition, by mass percentage, contains 5-7% Si, 4-7% Al, 0.3-0.5% C, 1.3-1.5% P, with the balance being Fe; The carbonyl iron powder contains, by mass percentage: N≤0.008%, O≤0.6%, C≤0.02%, with the balance being Fe; The carbonyl iron powder accounts for 15-25% of the raw material powder by mass, the iron-silicon-aluminum powder accounts for 5-15% of the raw material powder by mass, and the filler powder accounts for 25-35% of the raw material powder by mass.

2. The low-loss FeSi@CIP composite soft magnetic powder core according to claim 1, characterized in that, The filler powder is added at a mass ratio of 27% to 32% of the raw material powder.

3. The low-loss FeSi@CIP composite soft magnetic powder core according to claim 1, characterized in that, The amorphous nanocrystalline atomized FeSi powder has a particle size of 25–35 μm. The carbonyl iron powder has a particle size of 12–16 μm, and the iron-silicon-aluminum powder has a particle size of 15–25 μm.

4. The method for preparing a low-loss FeSi@CIP composite soft magnetic powder core according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Powder pretreatment: Amorphous nanocrystalline atomized FeSi powder and iron-silicon-aluminum powder are pre-calcined at 350℃~400℃ in a hydrogen atmosphere. (2) Mixing raw materials: The amorphous nanocrystalline atomized FeSi powder obtained in step (1), iron-silicon-aluminum powder, and carbonyl iron powder are mixed evenly in proportion to obtain a mixed powder. (3) Passivation: The mixed powder is subjected to phosphoric acid passivation treatment; (4) Insulation coating treatment: The acetone solution of epoxy resin and phenolic amine epoxy curing agent is uniformly stirred to achieve insulation coating of the mixed powder. After drying, the mixed powder required for temperature pressing is obtained. (5) Warm pressing: Weigh an appropriate amount of the mixed powder obtained in step (4), heat it to the warm pressing temperature and put it into a preheated warm pressing mold for pressing. The pressing temperature is 180 ℃~300 ℃. In the first stage, the pressure is 500 MPa~600 MPa for 2~6 min, and in the second stage, the pressure is 1000 MPa~1200 MPa for 3~5 min. After pressing, a low-loss FeSi@CIP composite soft magnetic powder core is obtained.

5. The method for preparing low-loss FeSi@CIP composite soft magnetic powder core according to claim 4, characterized in that, The passivation is performed using a phosphoric acid passivation solution made of a mixture of acetone and phosphoric acid.

6. The method for preparing low-loss FeSi@CIP composite soft magnetic powder core according to claim 4, characterized in that, The drying step (4) is performed at 80 ℃~100 ℃ for 1~2 h.

7. The method for preparing low-loss FeSi@CIP composite soft magnetic powder core according to claim 4, characterized in that, The first stage of step (5) involves pressing at 530 MPa pressure, and the second stage involves pressing at 1050 MPa pressure.

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