Iron-silicon magnetic powder core, preparation method thereof and inductor

Abstract

The application relates to a ferrosilicon magnetic powder core and a preparation method and an inductor thereof, and the preparation method comprises the following steps: (1) mixing ferrosilicon alloy magnetic powder and a surface treatment agent to obtain surface treatment magnetic powder; (2) mixing a passivation agent, a solvent and the surface treatment magnetic powder in step (1) to obtain passivation magnetic powder; (3) performing organic insulation bonding on the passivation magnetic powder in step (2) to obtain bonded magnetic powder; (4) mixing a demolding agent and the bonded magnetic powder in step (3) to obtain mixed magnetic powder material; and (5) performing compression molding and annealing treatment on the mixed magnetic powder material in step (4) to obtain the ferrosilicon magnetic powder core. The ferrosilicon magnetic powder core obtained by the preparation method provided by the application improves insulation effect, reduces eddy current loss, and improves the problems of high loss increase and rapid temperature rise after the temperature rise of the magnetic powder core.

Description

Technical Field

[0001] This invention belongs to the field of soft magnetic alloy materials and powder metallurgy technology, and relates to a method for preparing an iron-silicon magnetic powder core, particularly an iron-silicon magnetic powder core, its preparation method, and an inductor. Background Technology

[0002] Iron and silicon alloy magnetic powder and the magnetic powder cores they manufacture have been widely used in various fields, including AC inductors, output inductors, photovoltaic power inverter inductors, and boost inductors for new energy charging piles, due to their high DC superposition characteristics, noiselessness, and low cost. With the increasing demand for fast charging and the development of power electronics technology, power density is rapidly increasing, placing higher demands on magnetic inductor components. In particular, increased load and higher DC superposition require iron-silicon magnetic cores to withstand larger currents. Large currents will cause the magnetic core to heat up rapidly, further increasing iron-silicon losses. This cycle will eventually lead to core failure.

[0003] The main manufacturing process of metal soft magnetic powder cores involves mixing metal powder with insulating material, forming a uniform and dense insulating layer on the powder surface. After drying, lubricating powder is added, and the product is then molded into the desired shape in a press mold. Finally, the product is heat-treated under specific atmosphere and temperature conditions to eliminate defects and excess non-magnetic substances, resulting in a product with excellent overall performance. From the above manufacturing process, it can be seen that the main factors affecting the core loss and temperature characteristics are the iron-silicon magnetic powder and the insulating material used. The loss-temperature rise characteristic of iron-silicon alloys is inherent; therefore, the only way to change this temperature rise characteristic is to adjust the insulating material.

[0004] CN 112530656A discloses a method for preparing a low-loss iron-silicon magnetic powder core, comprising the following steps: alloy smelting, crushing, sieving, surface treatment, insulating coating, adding lubricant, pressing, heat treatment, and surface coating treatment; wherein, during the sieving process, a powder ratio of -325 mesh: -250 mesh: -120 mesh = 2:3:1 is used for powder proportioning; after heat treatment, the surface of the magnetic powder core is coated. The main component of the low-loss iron-silicon magnetic powder core of the present invention is a binary iron-silicon alloy with the addition of 0.22-0.25% chromium and 0.08-0.15% vanadium, 6.7-7.0% silicon, and the balance being iron. The iron-silicon magnetic powder core prepared by the present invention can achieve a saturation magnetic flux density of over 1.6T, and its volumetric loss Pcv at 50kHz and 500Gs can be as low as 125-135mW / cm². 3 The iron-silicon magnetic powder core of this invention has the advantages of high saturation magnetic flux density and low loss.

[0005] CN 113299451A discloses a FeNi nanoparticle / epoxy resin composite-coated iron-silicon magnetic powder core, the preparation method of which includes powder mixing, modification, insulating coating, drying, molding, and vacuum annealing. This invention uses iron-silicon powder as the main body, with a FeNi nanoparticle / epoxy resin coating layer constructed on the surface. Compared with existing related products, the resulting iron-silicon magnetic powder core has advantages such as low magnetic loss, high magnetic permeability, high product density, and low cost.

[0006] The above technical solutions all improve the low loss of magnetic powder cores. However, CN 112530656A still has shortcomings such as excessive molding pressure and complex powder particle size distribution. It also fails to fully disclose the changes in loss after the magnetic core temperature rises. In addition, the iron-silicon alloy powder production uses trace elements such as chromium and vanadium, which increase costs. It cannot solve the technical problem of iron-silicon rusting and does not achieve the effect of reducing raw material costs. CN 113299451A uses high-cost nano-FeNi materials and requires special processes such as drying in a vacuum environment. In addition, it does not fully explain the role of FeNi materials in this invention, and the magnetic permeability of the sample in the examples is not significantly improved. At the same time, the loss of the magnetic powder core obtained by this invention is higher than the industry standard, has no obvious advantages, and does not explain the change law of loss with the increase of magnetic core temperature.

[0007] Therefore, how to improve the problem that the loss of magnetic core increases with increasing temperature is an urgent problem to be solved in the fields of soft magnetic alloy materials and powder metallurgy technology. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides an iron-silicon magnetic powder core, its preparation method, and an inductor. By enhancing passivation and insulation effects, the heat dissipation performance of the magnetic powder core is improved, effectively solving the problems of high loss and rapid temperature rise in iron-silicon alloy magnetic powder cores.

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

[0010] In a first aspect, the present invention provides a method for preparing an iron-silicon magnetic powder core, the method comprising the following steps:

[0011] (1) Mix iron-silicon alloy magnetic powder with a surface treatment agent to obtain surface-treated magnetic powder;

[0012] (2) Mix the passivating agent, solvent and the surface-treated magnetic powder described in step (1) to obtain passivated magnetic powder;

[0013] (3) Organic insulating bonding is performed on the passivated magnetic powder obtained in step (2) to obtain bonded magnetic powder;

[0014] (4) Mix the release agent and the bonding magnetic powder described in step (3) to obtain a mixed magnetic powder material;

[0015] (5) The mixed magnetic powder material described in step (4) is pressed and annealed to obtain the iron-silicon magnetic powder core.

[0016] The preparation method provided by this invention, by enhancing passivation and insulation effects, changes the trend of increased loss after temperature rise in iron-silicon magnetic powder cores to a constant or even slightly reduced loss, thus overcoming the problem of increased temperature rise loss caused by superposition.

[0017] The iron-silicon alloy magnetic powder provided by this invention is a conventional iron-silicon alloy magnetic powder in the field and is not specifically limited thereto.

[0018] Preferably, the particle size range of the iron-silicon alloy magnetic powder in step (1) is 15 to 150 μm, for example, it can be 15 μm, 50 μm, 100 μm, 125 μm or 150 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, in the iron-silicon alloy magnetic powder of step (1), the mass of particles with a diameter range of 75 to 150 μm accounts for more than 40 wt% of the total mass, for example, it can be 40 wt%, 45 wt%, 50 wt%, 55 wt% or 65 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, in the iron-silicon alloy magnetic powder of step (1), the mass of particles with a diameter range of 15 to 35 μm accounts for more than 30% of the total mass, for example, it can be 30 wt%, 40 wt%, 45 wt%, 50 wt% or 55 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] The particle size range of the iron-silicon alloy magnetic powder provided by this invention increases the utilization rate of low-cost materials.

[0022] Preferably, the surface treatment agent in step (1) includes an organoaluminum aerosol.

[0023] The organic aluminum aerosol provided by this invention can effectively improve the surface condition of iron-silicon alloy magnetic powder, which is beneficial for its passivation treatment.

[0024] Preferably, the mass of the surface treatment agent in step (1) is 0.5 to 1.5 wt% of the iron-silicon alloy magnetic powder, for example, it can be 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt% or 1.5 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the mixing in step (1) further includes drying.

[0026] Preferably, the drying temperature is 75-85°C, for example, 75°C, 78°C, 80°C, 82°C or 85°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the passivating agent in step (2) comprises a water-soluble inorganic material, preferably phosphoric acid and / or aluminum dihydrogen phosphate.

[0028] Preferably, the mass of the passivating agent in step (2) is 0.15 to 2.5 wt% of the iron-silicon alloy magnetic powder, for example, it can be 0.15 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 2 wt% or 2.5 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, the solvent in step (2) includes deionized water.

[0030] Preferably, the mass of the solvent in step (2) is 1.5 to 3 times that of the passivating agent, for example, it can be 1.5 times, 1.8 times, 2 times, 2.5 times or 3 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the mixing in step (2) further includes drying.

[0032] Preferably, step (3) further includes mixing a silane coupling agent with the passivating magnetic powder described in step (2) before the organic insulating bonding.

[0033] The silane coupling agent provided by this invention is mixed with passivating magnetic powder before bonding, which increases the uniformity of the adhesive coating on the surface of the magnetic powder and is beneficial to enhancing the penetration of the adhesive.

[0034] The silane coupling agent comprises any one or a combination of at least two of vinylsilanes, aminosilanes, or methacryloxysilanes. Typical but non-limiting combinations include combinations of vinylsilanes and aminosilanes, combinations of aminosilanes and methacryloxysilanes, combinations of vinylsilanes and methacryloxysilanes, or combinations of vinylsilanes, aminosilanes, and methacryloxysilanes.

[0035] The silane coupling agent provided by this invention can improve the dispersibility and adhesion of fillers in resins, improve the compatibility between inorganic fillers and resins, and enhance the mechanical, electrical and weather resistance properties of fillers.

[0036] Preferably, the mass of the silane coupling agent is 0.15 to 0.5 wt% of the iron-silicon alloy magnetic powder, for example, it can be 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.4 wt% or 0.5 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the organic insulating bonding method in step (3) is: mixing the adhesive solution with the passivating magnetic powder in step (2), drying and sieving.

[0038] Preferably, the adhesive in the adhesive solution includes an organosilicon resin.

[0039] Preferably, the silicone resin includes high-temperature resistant silicone resin and / or modified silicone resin, and more preferably polymethyl silicone resin and / or polysilane silicone resin.

[0040] The organosilicon resin provided by this invention can improve the insulation properties of powder, improve the compatibility between inorganic fillers and resin, improve powder formability and increase density, etc.

[0041] Preferably, the solvent in the adhesive solution includes acetone.

[0042] Preferably, the mass of the binder in the binder solution is 0.3 to 1.5 wt% of the iron-silicon alloy magnetic powder, for example, it can be 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, or 1.5 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Preferably, the mass of the solvent in the adhesive solution is 1 to 5 times that of the adhesive, for example, it can be 1, 2, 3, 4 or 5 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] Preferably, the mesh size of the sieve is 80 to 200 mesh, for example, it can be 80 mesh, 100 mesh, 150 mesh, 180 mesh or 200 mesh, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] Preferably, the release agent in step (4) comprises zinc stearate.

[0046] Preferably, the mass of the release agent in step (4) is 0.3 to 0.5 wt% of the iron-silicon alloy magnetic powder, for example, it can be 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt% or 0.5 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0047] Preferably, the pressing pressure in step (5) is 1500-1800 MPa, for example, it can be 1500 MPa, 1550 MPa, 1600 MPa, 1700 MPa or 1800 MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0048] Preferably, the maximum temperature of the annealing treatment in step (5) is 680 to 730°C, for example, it can be 680°C, 690°C, 700°C, 710°C, 720°C or 730°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0049] Preferably, the holding time for the annealing treatment in step (5) is 25 to 35 minutes, for example, it can be 25 minutes, 28 minutes, 30 minutes, 32 minutes or 35 minutes, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0050] Preferably, the annealing process in step (5) further includes cooling and applying a paint coating.

[0051] Preferably, the paint material of the paint coating includes epoxy resin.

[0052] As a preferred embodiment of the preparation method described in the first aspect of the present invention, the preparation method includes the following steps:

[0053] (1) Mix iron-silicon alloy magnetic powder and organic aluminum aerosol, and dry at 75-85°C to obtain surface-treated magnetic powder; the mass of the organic aluminum aerosol is 0.5-1.5 wt% of the iron-silicon alloy magnetic powder.

[0054] (2) Mix the passivating agent, deionized water and the surface-treated magnetic powder from step (1), and dry them to obtain passivated magnetic powder; the passivating agent is 0.15 to 2.5 wt% of the iron-silicon alloy magnetic powder, and the mass of the deionized water is 1.5 to 3 times that of the passivating agent; the passivating agent is phosphoric acid and / or aluminum dihydrogen phosphate;

[0055] (3) After mixing 0.15 to 0.5 wt% of the iron-silicon alloy magnetic powder with the passivated magnetic powder in step (2), the mixture is then mixed with an organosilicon resin-acetone solution, dried, and passed through an 80 to 200 mesh sieve to obtain bonded magnetic powder; the mass of the organosilicon resin is 0.3 to 1.5 wt% of the iron-silicon alloy magnetic powder, and the mass of the acetone is 1 to 5 times that of the organosilicon resin;

[0056] (4) Mix zinc stearate and the bonding magnetic powder from step (3) at a mass of 0.3 to 0.5 wt% of the iron-silicon alloy magnetic powder to obtain a mixed magnetic powder material;

[0057] (5) The mixed magnetic powder material described in step (4) is pressed and molded under a pressure of 1500-1800 MPa, and then annealed at a maximum temperature of 680-730℃ for 25-35 minutes. After cooling, an epoxy resin coating is applied to obtain the iron-silicon magnetic powder core.

[0058] In the iron-silicon alloy magnetic powder described in step (1), the mass of particles with a diameter range of 75 to 150 μm accounts for more than 40 wt% of the total mass, the mass of particles with a diameter range of 15 to 35 μm accounts for more than 30% of the total mass, and the remaining particles have a diameter range of 35 to 75 μm.

[0059] In a second aspect, the present invention provides an iron-silicon magnetic powder core, which is obtained by the preparation method described in the first aspect.

[0060] Thirdly, the present invention provides an inductor containing an iron-silicon magnetic powder core as described in the second aspect.

[0061] Compared with the prior art, the present invention has at least the following beneficial effects:

[0062] (1) The iron-silicon magnetic powder core obtained by the preparation method provided by the present invention improves the passivation and insulation effect, reduces eddy current loss, and improves the problem of increased loss and excessively rapid temperature rise after the magnetic powder core is heated.

[0063] (2) The preparation method provided by the present invention is simple and does not require high equipment, and reduces material costs. Detailed Implementation

[0064] 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.

[0065] Example 1

[0066] This embodiment provides a method for preparing an iron-silicon magnetic powder core, the method comprising the following steps:

[0067] (1) Mixed iron-silicon alloy magnetic powder (silicon content 5wt%, the rest is iron) and 1wt% of organic aluminum aerosol (Changhe JR14W, nano aluminum aerosol) of iron-silicon alloy magnetic powder, dried at 80°C to obtain surface-treated magnetic powder.

[0068] In the iron-silicon alloy magnetic powder, the mass of particles with a diameter range of 75-150 μm accounts for 40 wt% of the total mass, the mass of particles with a diameter range of 15-35 μm accounts for 30% of the total mass, and the remaining particles have a diameter range of 35-75 μm.

[0069] (2) Mix phosphoric acid, deionized water and the surface-treated magnetic powder from step (1), and dry them to obtain passivated magnetic powder;

[0070] The mass of the phosphoric acid is 1 wt% of the iron-silicon alloy magnetic powder; the mass of the deionized water is twice that of the phosphoric acid.

[0071] (3) Add 0.25 wt% of vinyl silane coupling agent of the iron-silicon alloy magnetic powder to the passivated magnetic powder in step (2), and then mix it with organosilicon resin (domestic FJN-9802 high temperature organosilicon)-acetone solution, dry it and pass it through a 100-mesh sieve to obtain the bonded magnetic powder.

[0072] The mass of the organosilicon resin is 1 wt% of the iron-silicon alloy magnetic powder, and the mass of the acetone is 3 times that of the organosilicon resin;

[0073] (4) Mix zinc stearate (0.4 wt% of the iron-silicon alloy magnetic powder) and the bonding magnetic powder from step (3) to obtain a mixed magnetic powder material;

[0074] (5) The mixed magnetic powder material described in step (4) is pressed and molded at a pressure of 1700 MPa, and then annealed at a maximum temperature of 700°C for 30 minutes. After cooling, an epoxy resin coating is applied to obtain the iron-silicon magnetic powder core.

[0075] Example 2

[0076] This embodiment provides a method for preparing an iron-silicon magnetic powder core, the method comprising the following steps:

[0077] (1) Mixed iron-silicon alloy magnetic powder (silicon content 4.5wt%, the rest is iron) and 0.5wt% of organic aluminum aerosol (Changhe JR14W, nano aluminum aerosol) of iron-silicon alloy magnetic powder by mass, and dried at 85℃ to obtain surface-treated magnetic powder.

[0078] In the iron-silicon alloy magnetic powder, the mass of particles with a diameter range of 75-150 μm accounts for 45 wt% of the total mass, the mass of particles with a diameter range of 15-35 μm accounts for 35% of the total mass, and the remaining particles have a diameter range of 35-75 μm.

[0079] (2) Mix aluminum dihydrogen phosphate, deionized water and the surface-treated magnetic powder from step (1), and dry them to obtain passivated magnetic powder;

[0080] The mass of aluminum dihydrogen phosphate is 0.15 wt% of the iron-silicon alloy magnetic powder; the mass of deionized water is 1.5 times that of aluminum dihydrogen phosphate.

[0081] (3) Add 0.15 wt% of aminosilane coupling agent of the iron-silicon alloy magnetic powder to the passivation magnetic powder in step (2), then mix with polymethyl silicone resin-acetone solution, dry and pass through an 80-mesh sieve to obtain bonded magnetic powder.

[0082] The mass of the polymethyl silicone resin is 0.3 wt% of the iron-silicon alloy magnetic powder, and the mass of the acetone is 1 times that of the polymethyl silicone resin;

[0083] (4) Mix zinc stearate (0.3 wt% of the iron-silicon alloy magnetic powder) and the bonding magnetic powder from step (3) to obtain a mixed magnetic powder material;

[0084] (5) The mixed magnetic powder material described in step (4) is pressed and molded at a pressure of 1500 MPa, and then annealed at a maximum temperature of 730°C for 25 minutes. After cooling, an epoxy resin coating is applied to obtain the iron-silicon magnetic powder core.

[0085] Example 3

[0086] This embodiment provides a method for preparing an iron-silicon magnetic powder core, the method comprising the following steps:

[0087] (1) Mixed iron-silicon alloy magnetic powder (silicon content 6.5wt%, the rest is iron) and 1.5wt% of organic aluminum aerosol (Changhe JR14W, nano aluminum aerosol) of iron-silicon alloy magnetic powder were dried at 75°C to obtain surface-treated magnetic powder.

[0088] In the iron-silicon alloy magnetic powder, the mass of particles with a diameter range of 75-150 μm accounts for 42 wt% of the total mass, the mass of particles with a diameter range of 15-35 μm accounts for 32% of the total mass, and the remaining particles have a diameter range of 35-75 μm.

[0089] (2) Mix phosphoric acid, deionized water and the surface-treated magnetic powder from step (1), and dry them to obtain passivated magnetic powder;

[0090] The phosphoric acid is 2.5 wt% of the iron-silicon alloy magnetic powder; the deionized water is 3 times the mass of the phosphoric acid.

[0091] (3) After adding 0.5 wt% of methacryloxysilane coupling agent (by weight of the iron-silicon alloy magnetic powder) to the passivated magnetic powder obtained in step (2), it is then mixed with a polysilane silicone resin-acetone solution, dried, and passed through a 200-mesh sieve to obtain bonded magnetic powder.

[0092] The mass of the polysilane silicone resin is 1.5 wt% of the iron-silicon alloy magnetic powder, and the mass of the acetone is 5 times that of the organosilicon resin;

[0093] (4) Mix zinc stearate (0.5 wt% of the iron-silicon alloy magnetic powder) and the bonding magnetic powder from step (3) to obtain a mixed magnetic powder material;

[0094] (5) The mixed magnetic powder material described in step (4) is pressed and molded at a pressure of 1800 MPa, and then annealed at a maximum temperature of 680°C for 35 minutes. After cooling, an epoxy resin coating is applied to obtain the iron-silicon magnetic powder core.

[0095] Example 4

[0096] This embodiment provides a method for preparing an iron-silicon magnetic powder core. The difference from Embodiment 1 is only that in the iron-silicon alloy magnetic powder described in step (1), the mass of particles with a diameter range of 75 to 150 μm accounts for 30 wt% of the total mass, the mass of particles with a diameter range of 15 to 35 μm accounts for 30% of the total mass, and the remaining particles have a diameter range of 35 to 75 μm.

[0097] Example 5

[0098] This embodiment provides a method for preparing an iron-silicon magnetic powder core. The difference from Embodiment 1 is only that in the iron-silicon alloy magnetic powder described in step (1), the mass of particles with a diameter range of 75 to 150 μm accounts for 40 wt% of the total mass, the mass of particles with a diameter range of 15 to 35 μm accounts for 20% of the total mass, and the remaining particles have a diameter range of 35 to 75 μm.

[0099] Example 6

[0100] This embodiment provides a method for preparing an iron-silicon magnetic powder core, which differs from Embodiment 1 only in that the mass of phosphoric acid in step (2) is 0.1 wt% of the iron-silicon alloy magnetic powder.

[0101] Example 7

[0102] This embodiment provides a method for preparing an iron-silicon magnetic powder core, which differs from Embodiment 1 only in that the mass of phosphoric acid in step (2) is 2.8 wt% of the iron-silicon alloy magnetic powder.

[0103] Example 8

[0104] This embodiment provides a method for preparing an iron-silicon magnetic powder core. The only difference from Embodiment 1 is that in step (3), before mixing with the organosilicon resin-acetone solution, the operation of mixing with the silane coupling agent is not performed.

[0105] Example 9

[0106] This embodiment provides a method for preparing an iron-silicon magnetic powder core, which differs from Embodiment 1 only in that the mass of the silane coupling agent in step (3) is 0.1 wt% of the iron-silicon alloy magnetic powder.

[0107] Example 10

[0108] This embodiment provides a method for preparing an iron-silicon magnetic powder core, which differs from Embodiment 1 only in that the mass of the silane coupling agent in step (3) is 0.7 wt% of the iron-silicon alloy magnetic powder.

[0109] Example 11

[0110] This embodiment provides a method for preparing an iron-silicon magnetic powder core. The only difference from Embodiment 1 is that in step (3), the mass of the organosilicon resin is 0.2 wt% of the iron-silicon alloy magnetic powder.

[0111] Example 12

[0112] This embodiment provides a method for preparing an iron-silicon magnetic powder core. The only difference from Embodiment 1 is that in step (3), the mass of the organosilicon resin is 1.8 wt% of the iron-silicon alloy magnetic powder.

[0113] Comparative Example 1

[0114] This comparative example provides a method for preparing an iron-silicon magnetic powder core. The only difference from Example 1 is that in step (3), the silicone resin is replaced with an equal mass of glass powder (Ammi T800 glass powder).

[0115] Comparative Example 2

[0116] This comparative example provides a method for preparing an iron-silicon magnetic powder core, the only difference from Example 1 is that in step (3), the organosilicon resin is replaced with an equal mass of silicon dioxide.

[0117] The obtained iron-silicon magnetic powder core was tested.

[0118] Inductance test conditions: 20 turns of wire, frequency 100kHz.

[0119] Loss test conditions: 50kHz, 100mT load.

[0120] Test temperatures: 25℃, 50℃, 100℃, 150℃.

[0121] The winding consists of 22 turns + 22 turns, with the input and output windings being the same.

[0122] The test results are shown in Tables 1 and 2 below.

[0123] Table 1

[0124]

[0125]

[0126] Table 2

[0127] Test number <![CDATA[Loss (mW / cm 3 , 25 °C)]]> 50℃ 100℃ 150℃ Example 1 521.12 516.77 512.47 511.22 Example 2 508.40 507.57 507.52 503.49 Example 3 512.46 510.45 510.43 507.35 Example 4 535.11 534.28 528.76 520.63 Example 5 528.14 524.18 523.87 519.09 Example 6 531.31 530.45 528.29 525.13 Example 7 553.45 553.21 550.23 545.78 Example 8 529.89 528.77 524.81 519.23 Example 9 533.23 530.25 528.78 525.67 Example 10 535.78 530.58 527.48 519.06 Example 11 543.72 539.57 530.74 521.43 Example 12 574.32 572.62 570.11 571.04 Comparative Example 1 521.78 535.30 539.91 542.39 Comparative Example 2 514.52 527.47 534.20 537.27

[0128] The following conclusions can be drawn from Tables 1 and 2:

[0129] (1) As can be seen from Examples 1-3, the iron-silicon magnetic powder cores obtained by the preparation method provided by the present invention improve the passivation and insulation effects, reduce eddy current losses, and improve the problem of increased losses and excessively rapid temperature rise after the magnetic powder cores are heated.

[0130] (2) As can be seen from the comparison between Examples 4 and 5 and Example 1, when the particle size range of the iron-silicon alloy magnetic powder is changed beyond the preferred range of the present invention, the loss of the magnetic powder core is increased and the quality is reduced. At the same time, the amount of magnetic powder core in the range of 35 to 75 μm is increased, which increases the preparation cost.

[0131] (3) As can be seen from the comparison between Examples 6 and 7 and Example 1, when the mass of the passivating agent in step (2) is changed beyond the preferred range of the present invention, the loss of the magnetic powder core is increased and the inductance and quality of the magnetic powder core are reduced.

[0132] (4) As can be seen from the comparison between Example 8 and Example 1, when no silane coupling agent is added in step (3), the loss of the magnetic powder core is increased and the quality of the magnetic powder core is reduced.

[0133] (5) As can be seen from the comparison between Examples 9 and 10 and Example 1, when the quality of the silane coupling agent in step (3) is not within the preferred range of the present invention, the inductance and quality of the magnetic powder core are reduced, and the loss of the magnetic powder core is increased.

[0134] (6) As can be seen from the comparison between Examples 11 and 12 and Example 1, when the quality of the silicone resin in step (3) is not within the preferred range of the present invention, the inductance and quality of the magnetic powder core are reduced, and the loss of the magnetic powder core is increased.

[0135] (7) As can be seen from the comparison of Comparative Examples 1 and 2 with Example 1, when inorganic bonding is replaced with organic bonding in step (3), the inductance and quality of the magnetic powder core are reduced, and the problem of increased temperature rise loss of the magnetic powder core cannot be solved.

[0136] In summary, the iron-silicon magnetic powder core prepared by the method provided by this invention improves passivation and insulation effects, reduces eddy current losses, and addresses the problems of increased losses and excessively rapid temperature rise after the magnetic powder core is heated. Furthermore, the preparation method provided by this invention is simple, requires minimal equipment, and reduces material costs.

[0137] The present invention has been illustrated with the above embodiments to describe the detailed process flow of the present invention. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an iron-silicon magnetic powder core, characterized in that, The preparation method includes the following steps: (1) Mix iron-silicon alloy magnetic powder with a surface treatment agent to obtain surface-treated magnetic powder; In the iron-silicon alloy magnetic powder, the particle size range of 75~150μm accounts for more than 40wt% of the total mass; in the iron-silicon alloy magnetic powder, the particle size range of 15~35μm accounts for more than 30% of the total mass; the surface treatment agent includes organoaluminum aerosol. (2) Mix the passivating agent, solvent and the surface-treated magnetic powder described in step (1) to obtain passivated magnetic powder; (3) Organic insulating bonding is performed on the passivated magnetic powder obtained in step (2) to obtain bonded magnetic powder; Step (3) before the organic insulating bonding process includes mixing a silane coupling agent with the passivating magnetic powder from step (2); the mass of the silane coupling agent is 0.15~0.4wt% of the iron-silicon alloy magnetic powder. (4) Mix the release agent and the bonding magnetic powder described in step (3) to obtain a mixed magnetic powder material; (5) The mixed magnetic powder material described in step (4) is pressed and annealed to obtain the iron-silicon magnetic powder core.

2. The preparation method according to claim 1, characterized in that, The particle size range of the iron-silicon alloy magnetic powder in step (1) is 15~150μm.

3. The preparation method according to claim 1, characterized in that, The mass of the surface treatment agent in step (1) is 0.5~1.5wt% of the iron-silicon alloy magnetic powder.

4. The preparation method according to claim 1, characterized in that, Step (1) includes drying after mixing.

5. The preparation method according to claim 4, characterized in that, The drying temperature is 75~85℃.

6. The preparation method according to claim 1, characterized in that, The passivating agent in step (2) includes water-soluble inorganic materials.

7. The preparation method according to claim 6, characterized in that, The passivating agent in step (2) is phosphoric acid and / or aluminum dihydrogen phosphate.

8. The preparation method according to claim 1, characterized in that, The mass of the passivating agent in step (2) is 0.15~2.5wt% of the iron-silicon alloy magnetic powder.

9. The preparation method according to claim 1, characterized in that, The solvent in step (2) includes deionized water.

10. The preparation method according to claim 1, characterized in that, The mass of the solvent in step (2) is 1.5 to 3 times that of the passivating agent.

11. The preparation method according to claim 1, characterized in that, Step (2) further includes drying after mixing.

12. The preparation method according to claim 1, characterized in that, The organic insulating bonding method in step (3) is as follows: mix the adhesive solution with the passivating magnetic powder in step (2), dry and sieve.

13. The preparation method according to claim 12, characterized in that, The adhesive in the adhesive solution includes silicone resin.

14. The preparation method according to claim 12, characterized in that, The solvent in the adhesive solution includes acetone.

15. The preparation method according to claim 12, characterized in that, The mass of the binder in the binder solution is 0.3~1.5 wt% of the iron-silicon alloy magnetic powder.

16. The preparation method according to claim 12, characterized in that, The mass of the solvent in the adhesive solution is 1 to 5 times that of the adhesive.

17. The preparation method according to claim 12, characterized in that, The sieve mesh size is 80~200 mesh.

18. The preparation method according to claim 1, characterized in that, The release agent in step (4) includes zinc stearate.

19. The preparation method according to claim 1, characterized in that, The mass of the release agent in step (4) is 0.3~0.5 wt% of the iron-silicon alloy magnetic powder.

20. The preparation method according to claim 1, characterized in that, The pressing pressure in step (5) is 1500~1800MPa.

21. The preparation method according to claim 1, characterized in that, The maximum temperature for the annealing process in step (5) is 680~730°C.

22. The preparation method according to claim 1, characterized in that, The holding time for the annealing treatment in step (5) is 25~35 minutes.

23. The preparation method according to claim 1, characterized in that, Step (5) after annealing also includes cooling and applying a paint coating.

24. The preparation method according to claim 23, characterized in that, The paint material for the paint coating includes epoxy resin.

25. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Mix iron-silicon alloy magnetic powder and organoaluminum aerosol, and dry at 75~85℃ to obtain surface-treated magnetic powder; the mass of the organoaluminum aerosol is 0.5~1.5wt% of the iron-silicon alloy magnetic powder; (2) Mix the passivating agent, deionized water and the surface-treated magnetic powder from step (1), and dry them to obtain passivated magnetic powder; the passivating agent is 0.15~2.5wt% of the iron-silicon alloy magnetic powder, and the mass of the deionized water is 1.5~3 times that of the passivating agent; the passivating agent is phosphoric acid and / or aluminum dihydrogen phosphate; (3) After mixing 0.15~0.5wt% of the iron-silicon alloy magnetic powder with the passivated magnetic powder in step (2), the mixture is then mixed with an organosilicon resin-acetone solution, dried, and passed through an 80~200 mesh sieve to obtain bonded magnetic powder; the mass of the organosilicon resin is 0.3~1.5wt% of the iron-silicon alloy magnetic powder, and the mass of the acetone is 1~5 times that of the organosilicon resin; (4) Mix zinc stearate and the bonding magnetic powder from step (3) at a mass of 0.3~0.5 wt% of the iron-silicon alloy magnetic powder to obtain a mixed magnetic powder material; (5) The mixed magnetic powder material described in step (4) is pressed and molded under a pressure of 1500~1800MPa, and then annealed at a maximum temperature of 680~730°C for 25~35min. After cooling, an epoxy resin coating is applied to obtain the iron-silicon magnetic powder core. In the iron-silicon alloy magnetic powder of step (1), the mass of particles with a diameter range of 75~150μm accounts for more than 40wt% of the total mass, the mass of particles with a diameter range of 15~35μm accounts for more than 30% of the total mass, and the remaining particles have a diameter range of 35~75μm.

26. A type of iron-silicon magnetic powder core, characterized in that, The iron-silicon magnetic powder core is obtained by the preparation method described in any one of claims 1-25.

27. An inductor, characterized in that, The inductor contains an iron-silicon magnetic powder core as described in claim 26.

Images