An impregnating liquid for an iron-based alloy magnetic powder core and an impregnating method based on the above impregnating liquid

Abstract

The present invention discloses an impregnating solution for an iron-based alloy magnetic powder core and an impregnating method based on the above impregnating solution, which is prepared from components in the following mass percentages: 5-15% metal organic compound, 5-20% resin, and 65-90% organic solvent. The impregnating method includes the following steps: (1) putting the iron-based alloy powder before insulation into the impregnating solution for soaking, and drying after soaking to obtain the impregnated iron-based alloy powder; (2) performing insulation treatment on the iron-based alloy powder with a nano-silica dispersion liquid, and using a powder metallurgy process to prepare an iron-based alloy magnetic powder core after the insulation treatment to obtain the iron-based alloy magnetic powder core; cleaning and drying the obtained iron-based alloy magnetic powder core to obtain the iron-based alloy magnetic powder core to be impregnated; (3) completely immersing the iron-based alloy magnetic powder core in the impregnating solution for soaking, and cleaning after soaking; (4) heating and curing the cleaned iron-based alloy magnetic powder core, and naturally cooling to obtain the impregnated iron-based alloy magnetic powder core.

Description

Technical Field

[0001] The present invention relates to an impregnating liquid for an iron-based alloy magnetic powder core, and also relates to an impregnating method based on the above impregnating liquid, belonging to the technical field of magnetic materials. Background Art

[0002] The iron-based alloy magnetic powder core is a soft magnetic composite material prepared by powder metallurgy process. Common ones include iron powder cores, iron-silicon powder cores, iron-nickel powder cores, and iron-silicon-aluminum powder cores. Due to their advantages such as high magnetic permeability, high saturation magnetic induction intensity, and high frequency stability, they are widely used in high-performance electronic components such as inductors, photovoltaic inverters, and active filters. However, with the continuous development of electronic devices towards high frequency, high efficiency, miniaturization, and integration, the requirements for iron-based alloy magnetic powder cores are also getting higher and higher. However, the traditional magnetic ring structure in the iron-based alloy magnetic powder core can no longer meet the actual market demand, and the advantages of the combined magnetic circuit device begin to gradually emerge. However, while the combined magnetic circuit device is developing rapidly, there are also difficult problems, especially the strength problem of the combined magnetic circuit core. Since the traditional ring structure will be subjected to a spraying process after the core treatment, compared with the combined core exposed outside, the strength of the core after spraying treatment can be better guaranteed. Therefore, improving the strength of the combined magnetic circuit core is the key to the wide application and stable operation of the combined magnetic circuit device.

[0003] At present, the improvement of the strength of the combined magnetic circuit core adopts an impregnation treatment. The impregnating liquid used in the impregnation treatment is obtained by dissolving resin in an organic solvent. The impregnation treatment process is to soak the iron-based alloy magnetic powder core in the impregnating liquid. However, the improvement of the strength of the combined magnetic circuit core by the above method is limited. If the core strength is improved by prolonging the infiltration time and increasing the concentration of the impregnating liquid, resin will remain on the surface of the treated product, which will seriously affect the appearance of the core on the one hand and significantly deteriorate the magnetic properties of the product on the other hand. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide an impregnating liquid for an iron-based alloy magnetic powder core; another object of the present invention is to provide an impregnating method based on the above impregnating liquid. The iron-based alloy magnetic powder core obtained by the method of the present invention can greatly improve the strength of the formed combined magnetic circuit core while improving its magnetic properties, thereby solving the problems of low strength of the existing combined magnetic circuit core, deterioration of magnetic properties after impregnation treatment, and influence on appearance after core overflow of glue.

[0005] Technical Solution: The impregnating liquid for an iron-based alloy magnetic powder core described in the present invention is prepared from the following components in mass percentage: 5-15% metal organic compound, 5-20% resin, and 65-90% organic solvent.

[0006] Among them, the metal organic compound is one of iron hydroxide, cobalt acetate or nickel acetate.

[0007] Among them, the resin is one of epoxy resin, phenolic resin or polyester resin.

[0008] Among them, the organic solvent is one of methanol, ethanol or acetone.

[0009] The impregnation method based on the above impregnating solution includes the following steps:

[0010] (1) Put the iron-based alloy powder before insulation into the impregnating solution for soaking, and dry it after soaking to obtain the impregnated iron-based alloy powder; the particle size D50 of the iron-based alloy powder is generally 30 - 60 μm;

[0011] (2) Insulate the iron-based alloy powder in step (1) with a nano-silica dispersion liquid, and perform pressing and annealing after insulation to obtain an iron-based alloy magnetic powder core (the iron-based alloy magnetic powder core is prepared by powder metallurgy process), clean and dry the obtained iron-based alloy magnetic powder core to obtain the iron-based alloy magnetic powder core to be impregnated;

[0012] (3) Completely immerse the iron-based alloy magnetic powder core in step (2) in the impregnating solution for soaking, and clean it after soaking;

[0013] (4) Heat and cure the cleaned iron-based alloy magnetic powder core, and after natural cooling, obtain the impregnated iron-based alloy magnetic powder core.

[0014] Among them, in step (1), the soaking temperature is 40 - 80 °C, and the soaking time is 20 - 60 min (heating can accelerate molecular movement and promote film formation); the drying temperature is 60 - 120 °C, and the drying time is 30 - 60 min.

[0015] Among them, in step (2), the addition amount of the nano-silica dispersion liquid is 10 - 16‰ of the mass of the iron-based alloy powder.

[0016] Among them, the mass concentration of the nano-silica dispersion liquid is 4 g / L.

[0017] Among them, in step (2), acetone is used for cleaning, and the cleaning time is 10 - 15 min; the drying temperature is 60 - 120 °C.

[0018] Among them, in step (3), the soaking time is 2 - 6 h, and the soaking temperature is 40 - 80 °C; acetone is used for cleaning, and the cleaning time is 30 - 60 min.

[0019] Among them, in step (4), the heating time is 2 - 6 h, and the heating temperature is 120 °C - 350 °C.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following remarkable effects:

[0021] (1) The impregnating solution formula of the present invention contains metal organic compounds. During the impregnation process of iron-based alloy magnetic powder particles, the metal organic compounds and the resin can form a composite film (resin and metal chelate film) on the surface of the iron-based alloy magnetic powder particles. On the one hand, it can effectively prevent the resin (adhesive substance) from volatilizing during the subsequent annealing treatment. On the other hand, the composite film can bond with nano-silica, thereby improving the density and stability of the insulating film, and further improving the coating effect of the insulating film on the iron-based alloy magnetic powder particles. At the same time, during the impregnation process of the iron-based alloy magnetic powder core, the impregnating solution of the present invention has good permeability and excellent high-temperature curing effect, so as to fully protect the iron-based alloy magnetic powder particles and the iron-based alloy magnetic powder core, achieving the purpose of significantly improving the strength of the iron-based alloy magnetic powder core;

[0022] (2) The impregnation method of the present invention adopts two impregnation treatments, which are respectively carried out on the iron-based alloy magnetic powder particles and the iron-based alloy magnetic powder core. The first impregnation treatment of the iron-based alloy magnetic powder particles can form a composite film on the surface of the magnetic powder particles. The composite film can bond with nano-silica during the subsequent insulation treatment, thereby improving the density and stability of the insulating film. The second impregnation treatment of the iron-based alloy magnetic powder core. Due to the existence of a large number of distributed air gaps inside the iron-based alloy magnetic powder core after pressing and annealing treatment, the impregnating solution has good permeability and curing effect at high temperature, and can penetrate well into the iron-based alloy magnetic powder core and cure quickly. Therefore, the method of the present invention not only ensures the coating effect of the insulating oxide, but also ensures the strength of the iron-based alloy magnetic powder core, achieving the effect that the treated iron-based alloy magnetic powder core can significantly improve the strength of the combined magnetic circuit magnetic core while also improving its magnetic properties. Description of the drawings

[0023] Figure 1 It is the scanning electron microscope image of the gas-atomized iron-silicon-aluminum magnetic powder particles after impregnation and insulation treatment and the cross-section scanning electron microscope image of the gas-atomized iron-silicon-aluminum magnetic powder core after impregnation treatment in Example 1; among them, (a) is the scanning electron microscope image of the gas-atomized iron-silicon-aluminum magnetic powder particles after impregnation and insulation treatment; (b) is the cross-section scanning electron microscope image of the gas-atomized iron-silicon-aluminum magnetic powder core after impregnation treatment. Detailed implementation manners

[0024] Example 1

[0025] The impregnating solution for the iron-based alloy magnetic powder core of the present invention is prepared by the following method: Mix 1 kg of iron hydroxide, 1 kg of phenolic resin and 18 kg of ethanol, ultrasonicate for 10 min, and then let it stand for 30 min to obtain the impregnating solution.

[0026] The impregnation method based on the above impregnating solution includes the following steps:

[0027] (1) Put 1000 g of gas-atomized iron-silicon-aluminum alloy powder (with a D50 particle size of 41 μm) before insulation into the impregnating solution for soaking. The soaking time is 20 min and the soaking temperature is 40 °C. After soaking, take it out and dry it. The drying temperature is 60 °C and the drying time is 30 min to obtain the impregnated gas-atomized iron-silicon-aluminum alloy powder.

[0028] (2) Add 10 g of nano-silica dispersion liquid (the mass concentration of the nano-silica dispersion liquid is 4 g / L) to 1000 g of the gas-atomized iron-silicon-aluminum alloy powder in step (1) for insulation treatment. After insulation treatment, press and anneal to obtain the gas-atomized iron-silicon-aluminum alloy magnetic powder core. Put the gas-atomized iron-silicon-aluminum alloy magnetic powder core into acetone and wash it for 10 min, then dry it. The drying temperature is 60 °C to obtain the gas-atomized iron-silicon-aluminum alloy magnetic powder core to be impregnated.

[0029] (3) Completely immerse the dried gas-atomized iron-silicon-aluminum alloy magnetic powder core in the impregnating solution for soaking. The soaking time is 2 h and the soaking temperature is 40 °C. After soaking, take it out and put it into acetone for washing. The washing time is 30 min. Among them, the impregnating solution is the same as the impregnating solution in step (1).

[0030] (4) Put the washed gas-atomized iron-silicon-aluminum alloy magnetic powder core into the oven for heat curing. The heating time is 2 h and the heating temperature is 350 °C. After natural cooling, obtain the impregnated gas-atomized iron-silicon-aluminum alloy magnetic powder core.

[0031] The relative magnetic permeability of the gas-atomized iron-silicon-aluminum alloy magnetic powder core prepared in Example 1 was tested to be 62.2 at 100 kHz / 1 V; the DC bias performance under a magnetic field strength of 100 Oe was 60.3%; the loss at 50 kHz / 100 mT was 221 mW / cm3; the breaking strength was 1733 N.

[0032] Figure 1 (a) is the scanning electron microscope image (SEM) of the magnetic powder particles of the gas-atomized iron-silicon-aluminum magnetic powder in Example 1 after impregnation and insulation treatment; through Figure 1 (a), it can be seen that the surface of the magnetic powder particles is tightly wrapped, mainly with silica bonded to the network film formed by metal organic compounds. Figure 1 (b) is the cross-section scanning electron microscope image of the magnetic core of the gas-atomized iron-silicon-aluminum magnetic powder core prepared in Example 1 after impregnation treatment. Through Figure 1 (b), it can be seen that the magnetic powder particles inside the magnetic core are in close contact with each other, and silica and the impregnated substance are continuously and evenly distributed between the particles, indicating that on the one hand, good isolation is achieved between the particles, which can improve the magnetic properties of the magnetic core, and at the same time, the particles are tightly bonded, making the magnetic core have good strength.

[0033] Comparative Example 1

[0034] Comparative Example 1 has a different formulation of the impregnating solution compared to Example 1. The impregnating solution of Comparative Example 1 was prepared by the following method: 4 kg of epoxy resin and 16 kg of acetone were mixed, ultrasonicated for 10 min, and then allowed to stand for 30 min to obtain the impregnating solution.

[0035] The impregnating method based on the above impregnating solution includes the following steps:

[0036] (1) 10 g of nano-silica dispersion (the mass concentration of the nano-silica dispersion is 4 g / L) was added to 1000 g of gas-atomized iron-silicon-aluminum alloy powder (the D50 of the particle size is 41 μm) before insulation for insulation treatment. After insulation treatment, pressing and annealing were carried out to obtain a gas-atomized iron-silicon-aluminum alloy magnetic powder core; the gas-atomized iron-silicon-aluminum alloy magnetic powder core was placed in acetone, washed for 10 min, and dried at a drying temperature of 60 °C to obtain the gas-atomized iron-silicon-aluminum alloy magnetic powder core to be impregnated.

[0037] (2) The dried gas-atomized iron-silicon-aluminum alloy magnetic powder core was completely immersed in the impregnating solution and soaked for 2 h at an immersion temperature of 40 °C; after soaking, it was taken out and washed in acetone for 30 min;

[0038] (3) The washed gas-atomized iron-silicon-aluminum alloy magnetic powder core was placed in an oven for heat curing for 2 h at a heating temperature of 350 °C. After natural cooling, the impregnated gas-atomized iron-silicon-aluminum alloy magnetic powder core was obtained.

[0039] Table 1 shows the performance comparison of the gas-atomized iron-silicon-aluminum alloy magnetic powder cores obtained in Example 1 and Comparative Example 1

[0040]

[0041] It can be seen from Table 1 that the overall magnetic properties of the gas-atomized iron-silicon-aluminum alloy magnetic powder core obtained by using the impregnating solution and process of the present invention are improved. Among them, the DC bias performance is increased by 1.6%, the loss at 50 kHz / 100 mT is decreased by 12.6%, and the tensile strength is increased by more than twice.

[0042] Example 2

[0043] The impregnating solution of the present invention for iron-based alloy magnetic powder cores was prepared by the following method: 2 kg of cobalt acetate, 2.7 kg of polyester resin, and 15.3 kg of methanol were mixed, ultrasonicated for 15 min, and then allowed to stand for 45 min to obtain the impregnating solution.

[0044] The impregnating method based on the above impregnating solution includes the following steps:

[0045] (1) Put 1000 g of iron-silicon-aluminum alloy powder prepared by ball milling before insulation (D50 of particle size is 56 μm) into the impregnating solution for soaking. The soaking time is 40 min and the soaking temperature is 60 °C. After soaking, take it out and dry it. The drying temperature is 90 °C and the drying time is 45 min to obtain the impregnated ball-milled iron-silicon-aluminum alloy powder.

[0046] (2) Add 13 g of nano-silica dispersion liquid (the mass concentration of nano-silica dispersion liquid is 4 g / L) to 1000 g of ball-milled iron-silicon-aluminum alloy powder in step (1) for insulation treatment. After insulation treatment, press and anneal to obtain ball-milled iron-silicon-aluminum alloy magnetic powder cores. Put the ball-milled iron-silicon-aluminum alloy magnetic powder cores into acetone and wash for 12 min, then dry. The drying temperature is 90 °C to obtain the ball-milled iron-silicon-aluminum alloy magnetic powder cores to be impregnated.

[0047] (3) Completely immerse the dried ball-milled iron-silicon-aluminum alloy magnetic powder cores into the impregnating solution for soaking. The soaking time is 4 h and the soaking temperature is 60 °C. After soaking, take it out and put it into acetone for washing. The washing time is 45 min. Among them, the impregnating solution is the same as that in step (1).

[0048] (4) Put the washed ball-milled iron-silicon-aluminum alloy magnetic powder cores into the oven for heat curing. The heating time is 4 h and the heating temperature is 230 °C. After natural cooling, obtain the impregnated ball-milled iron-silicon-aluminum alloy magnetic powder cores.

[0049] The relative magnetic permeability of the ball-milled iron-silicon-aluminum alloy magnetic powder cores prepared in Example 2 is tested to be 71.3 at 100 kHz / 1 V; the DC bias performance under a magnetic field strength of 100 Oe is 46.3%; the loss at 50 kHz / 100 mT is 269 mW / cm3; the tensile strength is 1523 N.

[0050] Example 3

[0051] The impregnating solution for iron-based alloy magnetic powder cores of the present invention is prepared by the following method: Mix 3 kg of nickel acetate, 4 kg of epoxy resin and 13 kg of acetone, ultrasonically treat for 20 min, and then let it stand for 60 min to obtain the impregnating solution.

[0052] The impregnating method based on the above impregnating solution includes the following steps:

[0053] (1) Put 1000 g of gas-atomized iron-silicon alloy powder before insulation (D50 of particle size is 35 μm) into the impregnating solution for soaking. The soaking time is 60 min and the soaking temperature is 80 °C. After soaking, take it out and dry it. The drying temperature is 120 °C and the drying time is 60 min to obtain the impregnated gas-atomized iron-silicon alloy powder.

[0054] (2) 16 g of nano-silica dispersion (the mass concentration of the nano-silica dispersion is 4 g / L) is added to 1000 g of gas-atomized iron-silicon alloy powder in step (1) for insulation treatment. After insulation treatment, pressing and annealing are carried out to obtain gas-atomized iron-silicon alloy magnetic powder cores. The gas-atomized iron-silicon alloy magnetic powder cores are put into acetone and washed for 15 min, and then dried. The drying temperature is 120 °C to obtain the gas-atomized iron-silicon alloy magnetic powder cores to be impregnated.

[0055] (3) The dried gas-atomized iron-silicon alloy magnetic powder cores are completely immersed in the impregnating solution and soaked for 6 h at a soaking temperature of 80 °C. After soaking, they are taken out and put into acetone for washing for 60 min. Among them, the impregnating solution is the same as the impregnating solution in step (1).

[0056] (4) The washed gas-atomized iron-silicon alloy magnetic powder cores are put into an oven for heat curing. The heating time is 6 h and the heating temperature is 120 °C. After natural cooling, the impregnated gas-atomized iron-silicon alloy magnetic powder cores are obtained.

[0057] The relative permeability of the gas-atomized iron-silicon alloy magnetic powder cores prepared in Example 3 is tested to be 58.2 at 100 kHz / 1 V; the DC bias performance under a magnetic field strength of 100 Oe is 79.2%; the loss at 50 kHz / 100 mT is 566 mW / cm3; the tensile strength is 2615 N.

[0058] Comparative Example 2

[0059] The only difference between Comparative Example 2 and Example 1 is that there is no treatment in step (1) during the impregnation process. Specifically:

[0060] The impregnating solution used in the present invention for iron-based alloy magnetic powder cores is prepared by the following method: 1 kg of iron hydroxide, 1 kg of phenolic resin and 18 kg of ethanol are mixed, ultrasonicated for 10 min, and then left standing for 30 min to obtain the impregnating solution.

[0061] The impregnation method based on the above impregnating solution includes the following steps:

[0062] (1) 10 g of nano-silica dispersion (the mass concentration of the nano-silica dispersion is 4 g / L) is added to 1000 g of gas-atomized iron-silicon-aluminum alloy powder (the D50 of the particle size is 41 μm) before insulation for insulation treatment. After insulation treatment, pressing and annealing are carried out to obtain gas-atomized iron-silicon-aluminum alloy magnetic powder cores. The gas-atomized iron-silicon-aluminum alloy magnetic powder cores are put into acetone and washed for 10 min, and then dried. The drying temperature is 60 °C to obtain the gas-atomized iron-silicon-aluminum alloy magnetic powder cores to be impregnated.

[0063] (2) Immerse the dried gas-atomized iron-silicon-aluminum alloy magnetic powder cores completely in the impregnating liquid for 2 h at a soaking temperature of 40 °C. After soaking, take them out and wash them in acetone for 30 min.

[0064] (3) Put the washed gas-atomized iron-silicon-aluminum alloy magnetic powder cores into an oven for heat curing for 2 h at a heating temperature of 350 °C. After natural cooling, the impregnated gas-atomized iron-silicon-aluminum alloy magnetic powder cores are obtained.

[0065] The relative permeability of the gas-atomized iron-silicon-aluminum alloy magnetic powder cores prepared in Comparative Example 2 was measured to be 61.6 at 100 kHz / 1 V; the DC bias performance under a magnetic field strength of 100 Oe was 58.9%; the loss at 50 kHz / 100 mT was 233 mW / cm3; and the breaking strength was 1322 N.

Claims

1. A method for impregnating an iron-based alloy magnetic powder core, characterized in that: The steps include: (1) Putting the iron-based alloy powder before insulation into the impregnation liquid for immersion, and drying after immersion to obtain the iron-based alloy powder after impregnation; the immersion temperature is 40-80°C, and the immersion time is 20-60 minutes; (2) insulating the iron-based alloy powder of step (1) with a nano-silicon oxide dispersion, and preparing an iron-based alloy magnetic powder core by a powder metallurgy process after the insulation treatment to obtain an iron-based alloy magnetic powder core; washing and drying the obtained iron-based alloy magnetic powder core to obtain an iron-based alloy magnetic powder core to be impregnated; (3) completely immersing the iron-based alloy magnetic powder core of step (2) in the impregnation liquid, and then washing it; the immersion time is 2 to 6 hours, and the immersion temperature is 40 to 80°C; (4) heating and curing the cleaned iron-based alloy magnetic powder core, and naturally cooling the core to obtain an impregnated iron-based alloy magnetic powder core; The impregnation solution in step (1) and step (3) is prepared from the following components in percentage by mass: 5-15% of a metal organic compound or iron hydroxide, 5-20% of a resin and 65-90% of an organic solvent; the metal organic compound is cobalt acetate or nickel acetate.

2. The impregnation method for an iron-based alloy magnetic powder core according to claim 1, characterized in that: The resin is one of epoxy resin, phenolic resin or polyester resin.

3. The impregnation method for the iron-based alloy magnetic powder core according to claim 1, characterized in that: The organic solvent is one of methanol, ethanol or acetone.

4. The impregnation method for an iron-based alloy magnetic powder core according to claim 1, characterized in that: In step (1), the drying temperature is 60-120°C and the drying time is 30-60 minutes.

5. The impregnation method for the iron-based alloy magnetic powder core according to claim 1, characterized in that: In step (2), the amount of nano-silicon oxide dispersion added is 10-16‰ of the mass of the iron-based alloy powder.

6. The impregnation method for an iron-based alloy magnetic powder core according to claim 1, characterized in that: In step (2), the iron-based alloy magnetic powder core is cleaned with acetone for 10 to 15 minutes; the drying temperature is 60 to 120°C.

7. The impregnation method for an iron-based alloy magnetic powder core according to claim 1, characterized in that: In step (3), the iron-based alloy magnetic powder core is cleaned with acetone after immersion, and the cleaning time is 30 to 60 minutes.

8. The impregnation method for an iron-based alloy magnetic powder core according to claim 1, characterized in that: In step (4), the heating time is 2 to 6 hours, and the heating temperature is 120°C to 350°C.

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