Metal soft magnetic powder core and preparation method of metal soft magnetic powder core

Abstract

The invention provides a metal soft magnetic powder core and a preparation method of the metal soft magnetic powder core, and the preparation method of the metal soft magnetic powder core comprises the following steps: S1, carrying out insulation coating on metal soft magnetic powder, and then carrying out compression molding to obtain a magnetic powder core sample ring; and S2, the magnetic powder core sample ring is subjected to medium-frequency induction heating treatment, the metal soft magnetic powder core is obtained, by means of the medium-frequency induction heating treatment, the internal stress of the metal soft magnetic powder core can be rapidly eliminated, meanwhile, a high-resistance insulating layer is not damaged, and magnetic hysteresis loss and eddy current loss under high frequency are reduced. The preparation method is simple in preparation process and short in treatment time, a high-temperature treatment process is avoided, and the metal soft magnetic powder core high in magnetic conductivity and low in loss can be prepared.

Description

Technical Field

[0001] The invention relates to the field of metal soft magnetic materials, and in particular to a metal soft magnetic powder core and a preparation method of the metal soft magnetic powder core. Background Art

[0002] Metal soft magnetic material is an important magnetic functional material. It is a magnetic powder core made by coating the surface of soft magnetic particles with insulating material and forming and heat treating them. It has a distributed air gap, low loss, high saturation magnetization intensity, and excellent DC superposition characteristics. As electronic components develop towards miniaturization, high frequency, high current, and energy saving, the requirements for the characteristics of high-quality metal soft magnetic powder cores are getting higher and higher.

[0003] In the prior art, metal magnetic powder cores are subjected to high temperature annealing at 500°C to 900°C to eliminate stress and reduce hysteresis loss. However, long-term high-temperature heat treatment can easily destroy the insulating layer on the surface of the metal particles, reduce the resistance of the powder core, and worsen the high-frequency eddy current loss.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The main purpose of the present application is to provide a method for preparing a metal soft magnetic powder core, so as to solve the problem that the existing technology uses high-temperature heat treatment to eliminate internal stress, which is easy to damage the surface insulation layer of the metal particles, reduce the resistance of the metal soft magnetic powder core, and cause the high-frequency eddy current loss to worsen.

[0006] The present application provides a metal soft magnetic powder core and a preparation method of the metal soft magnetic powder core, the preparation method of the metal soft magnetic powder core comprising: step S1, first insulating and coating the metal soft magnetic powder, and then pressing and molding to obtain a magnetic powder core sample ring; step S2, performing medium frequency induction heating treatment on the magnetic powder core sample ring to obtain a metal soft magnetic powder core, by using medium frequency induction heating treatment, not only can the internal stress of the metal soft magnetic powder core be quickly eliminated, but also the high resistance insulation layer is not damaged, and the hysteresis loss and eddy current loss under high frequency are reduced. The preparation method has a simple preparation process, a short processing time, avoids high temperature processing, and can produce a metal soft magnetic powder core with high magnetic permeability and low loss.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a method for preparing a metal soft magnetic powder core is provided, and the preparation method comprises: step S1, first insulating and coating the metal soft magnetic powder, and then pressing and molding the metal soft magnetic powder to obtain a magnetic powder core sample ring; step S2, subjecting the magnetic powder core sample ring to medium frequency induction heating treatment to obtain a metal soft magnetic powder core.

[0008] Further, in step S2, the frequency of the medium frequency induction heating treatment is 0.5-20 kHz; and / or, the temperature of the medium frequency induction heating treatment is 500-900° C.; and / or, the time of the medium frequency induction heating treatment is 10-360 min.

[0009] Furthermore, in step S2, the medium frequency induction heating treatment is performed under the protection of an inert gas.

[0010] Furthermore, the inert gas includes at least one of nitrogen, argon and helium.

[0011] Furthermore, in step S1, the pressing pressure is 1000 MPa to 2500 MPa.

[0012] Furthermore, in step S1, the particle size of the metal soft magnetic powder is 200-1000 meshes.

[0013] Furthermore, in step S1, the material of the metal soft magnetic powder includes at least one of sendust aluminum, iron nickel, iron silicon, iron nickel molybdenum, and amorphous nanocrystals.

[0014] Furthermore, step S1 includes: step S11, mixing the metal soft magnetic powder with an acidic solution for passivation treatment, then adding an inorganic insulating agent for primary coating, and then adding silicone resin for secondary coating to obtain coated metal soft magnetic powder; step S12, mixing the coated metal soft magnetic powder with a binder and a release agent, and pressing and molding to obtain a magnetic powder core sample ring.

[0015] Furthermore, in step S11, the acidic substance includes at least one of phosphoric acid, oxalic acid, and boric acid; and the inorganic insulating agent includes at least one of silicon oxide, aluminum oxide, magnesium oxide, kaolin, mica powder, and diatomaceous earth.

[0016] Furthermore, the acidic substance is phosphoric acid.

[0017] Furthermore, based on the metal soft magnetic powder, the mass content of the acidic substance is 0.1-0.5%, the mass content of the inorganic insulating agent is 0.8-1.5%, and the mass content of the silicone resin is 0.2-0.5%.

[0018] Furthermore, in step S12, the adhesive includes at least one of polyvinyl alcohol, polyurethane, epoxy resin, and polyacrylate; and the release agent includes at least one of zinc stearate / magnesium / aluminum, graphite, and talcum powder.

[0019] Furthermore, the mass ratio of the binder to the metal soft magnetic powder is (0.5-2.5):100.

[0020] Furthermore, the mass ratio of the release agent to the metal soft magnetic powder is (0.1-1.5):100.

[0021] In order to achieve the above objective, according to one aspect of the present invention, a metal soft magnetic powder core is provided. The metal soft magnetic powder core is prepared according to the preparation method of the first aspect.

[0022] By applying the technical solution of the present application, the preparation method of the metal soft magnetic powder core provided by the present application can not only quickly eliminate the internal stress of the metal soft magnetic powder core, but also reduce the hysteresis loss and eddy current loss under high frequency without damaging the resistance insulation layer by using medium frequency induction heating treatment. The preparation method has a simple preparation process, a short processing time, avoids high temperature treatment process, and can produce a metal soft magnetic powder core with high magnetic permeability and low loss. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0024] As analyzed in the background technology of this application, since the prior art uses a high-temperature heat treatment method to eliminate the internal stress of metal soft magnetic powder, long-term high-temperature heat treatment can easily damage the surface insulation layer of the metal particles, reduce the resistance of the powder core, and worsen the high-frequency eddy current loss. In order to solve this problem, this application provides a metal soft magnetic powder core and a method for preparing a metal soft magnetic powder core.

[0025] In a typical embodiment of the present application, a method for preparing a metal soft magnetic powder core is provided, and the preparation method comprises: step S1, first insulating and coating the metal soft magnetic powder, and then pressing and molding the metal soft magnetic powder to obtain a magnetic powder core sample ring; step S2, subjecting the magnetic powder core sample ring to medium frequency induction heating treatment to obtain a metal soft magnetic powder core.

[0026] By applying the technical solution of the present application, the preparation method of the metal soft magnetic powder core provided by the present application can not only quickly eliminate the internal stress of the metal soft magnetic powder core, but also reduce the hysteresis loss and eddy current loss under high frequency without damaging the resistance insulation layer by using medium frequency induction heating treatment. The preparation method has a simple preparation process, a short processing time, avoids high temperature treatment process, and can produce a metal soft magnetic powder core with high magnetic permeability and low loss.

[0027] In the present application, the material of the metal soft magnetic powder is not limited, and it is the common metal soft magnetic powder in the art. The material of the metal soft magnetic powder used in the present application includes at least one of iron silicon aluminum, iron nickel, iron silicon, iron nickel molybdenum, and amorphous nanocrystals.

[0028] In some embodiments, the specific operating steps for preparing a magnetic powder core sample ring from metal soft magnetic powder include: step S11, mixing the metal soft magnetic powder with an acidic solution for passivation treatment, then adding an inorganic insulating agent for a primary coating, and then adding a silicone resin for a secondary coating to obtain a coated metal soft magnetic powder; step S12, mixing the coated metal soft magnetic powder with a binder and a release agent, and pressing and molding to obtain a magnetic powder core sample ring.

[0029] In the above step S11, the acidic substance includes at least one of phosphoric acid, oxalic acid, and boric acid, and is more preferably phosphoric acid. The metal soft magnetic powder is mixed with phosphoric acid for passivation treatment, which can form a phosphate insulating layer on the surface of the metal soft magnetic powder particles. The phosphate insulating layer is uniform and dense, which can effectively prevent the metal soft magnetic powder particles from contacting each other and reduce the formation of eddy currents.

[0030] In some embodiments, the above-mentioned inorganic insulating agent includes at least one of magnesium oxide, silicon oxide, aluminum oxide, magnesium oxide, kaolin, mica powder, and diatomaceous earth, preferably kaolin, and its average particle size is 0.05-15 μm. The inorganic insulating agent can be mixed with water and attached to the surface of the metal soft magnetic powder particles by physical adsorption, forming contact resistance on its surface, thereby achieving an insulating effect.

[0031] In the present application, silicone resin is a thermosetting polysiloxane cavity polymer with a highly cross-linked structure, which has the characteristics of high decomposition temperature and good insulation performance. It can not only form an insulating layer on the surface of metal soft magnetic powder particles, but also improve the heat resistance and mechanical strength of the metal soft magnetic powder, effectively reduce the high-frequency eddy current loss of the metal soft magnetic powder core, and avoid the problem of easy damage of the high-resistance insulating layer on the surface of the metal soft magnetic powder core particles during heating to eliminate the internal stress of the metal soft magnetic powder core.

[0032] In order to further improve the effect of the insulating coating, based on the metal soft magnetic powder, the mass content of the acidic substance is 0.1%, 0.2%, 0.3%, 0.4%, 0.5% or a range consisting of any two values, the mass content of the inorganic insulating agent is 0.8%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5% or a range consisting of any two values, and the mass content of the silicone resin is 0.2%, 0.3%, 0.4%, 0.5% or a range consisting of any two values.

[0033] In some embodiments, the passivated metal soft magnetic powder is coated with an inorganic insulating agent once, and then silicone resin is added for a second coating. By coating the surface of the passivated metal soft magnetic powder particles with an insulating layer, the metal soft magnetic powder particles are avoided from contacting each other, and the eddy current path between the magnetic powder particles is blocked, thereby suppressing the eddy current between the metal soft magnetic powders, effectively reducing the eddy current loss of the metal soft magnetic powder core, and at the same time increasing the resistivity of the magnetic powder core. In addition, the coating layer can improve the surface morphology of the magnetic powder particles and the adhesion between the magnetic powder particles, which is beneficial to improving the mechanical strength of the magnetic powder core.

[0034] In order to further improve the effect of the insulating coating, the particle size of the metal soft magnetic powder is preferably 200-1000 mesh. If the particle size of the metal soft magnetic powder is too small, eddy currents will easily form between the metal soft magnetic powder particles. Within the above range, it is beneficial for the inorganic insulating agent and silicone resin to be tightly coated on the surface of the metal soft magnetic powder, thereby improving the overall performance of the prepared metal soft magnetic powder core.

[0035] In the above step S12, there is no restriction on the type of adhesive, which is a common adhesive in the field. The present application adopts at least one of polyvinyl alcohol, polyurethane, epoxy resin, and polyacrylate to mix the coated metal soft magnetic powder with the adhesive, so that the coated metal soft magnetic powder particles can be aggregated and bonded. Among them, the mass ratio of the adhesive to the metal soft magnetic alloy is (0.5-2.5): 100. If the adhesive content is too high, the magnetic permeability of the metal soft magnetic powder core will be reduced. If the adhesive content is too low, the metal soft magnetic powder cannot be fully aggregated and bonded, which is not conducive to subsequent pressing and molding, thereby affecting the comprehensive performance of the metal soft magnetic powder core.

[0036] The release agent used in the present application includes at least one of zinc stearate / magnesium / aluminum, graphite, and talcum powder, and the mass ratio of the release agent to the metal soft magnetic powder is (0.1-1.5): 100. Among them, the amount of the release agent used within the above range is conducive to improving the fluidity of the metal soft magnetic powder, making the density distribution more uniform during the molding process, and not sticking to the mold.

[0037] In some embodiments, the coated metal soft magnetic powder is mixed with a binder and a release agent, and then pressed into shape using a hydraulic press. The pressing pressure is 1000MPa to 2500MPa. Under this pressure condition, the prepared magnetic powder core sample ring has a more stable structure and better performance. During the pressing process, stress is introduced into the interior of the magnetic powder core sample ring, resulting in increased hysteresis loss. In the subsequent process, medium-frequency induction heating treatment is used to eliminate the internal stress of the magnetic powder core sample ring.

[0038] In the present application, in the above step S2, there is no limitation on the equipment used for medium frequency induction heating, which is a common equipment in the art, and can perform medium frequency induction heating on the magnetic powder core sample ring. In some embodiments, a medium frequency induction heating device is used. The above medium frequency induction heating device includes a power supply and an induction coil. By passing a current of a certain frequency through the induction coil, the induction coil can generate a strong magnetic field, so that a large current is induced on the metal surface placed in the induction coil, thereby heating the metal and removing the internal stress of the metal.

[0039] In order to further improve the efficiency of eliminating the internal stress of the metal soft magnetic powder core, the current frequency of the medium frequency induction heating treatment is preferably 0.5 to 20 kHz. The higher the current frequency, the shallower the heating depth. If the current frequency is too high, the equipment requirements will be higher, and the cost of eliminating the internal stress of the metal soft magnetic powder core will also increase. In addition, a high current frequency will cause an increase in eddy current losses at high frequencies, so that the efficiency of induction heating will not increase significantly with the increase of the current frequency and will be close to saturation, resulting in an increase in the time of induction heating treatment. If the current frequency is too low, the efficiency of induction heating treatment will be reduced. When the current frequency is within the above range, the efficiency of eliminating the internal stress of the metal soft magnetic powder core can be effectively improved.

[0040] In this application, the current passing through the induction coil will generate an alternating magnetic field. When the magnetic field lines pass through the metal material, eddy currents are generated. On the one hand, the temperature of the metal soft magnetic powder core is increased, which plays a role in removing the internal stress of the metal soft magnetic powder core. On the other hand, the pinning effect of the magnetic domain wall of the magnetic material is weakened, and the domain wall displacement resistance is reduced, thereby reducing the hysteresis loss of the metal soft magnetic material at low frequency. In addition, the temperature of the medium frequency induction heating treatment can be indirectly controlled by controlling the current flow, so that the product is heated evenly, with high efficiency and energy saving, and automatic continuous production can be achieved.

[0041] In order to further eliminate the internal stress of the metal soft magnetic powder core, the preferred temperature of the medium frequency induction heating treatment is 500-900°C (such as 500°C, 550°C, 600°C, 700°C, 800°C, 900°C). If the temperature is too low, the internal stress of the metal soft magnetic powder core cannot be removed. If the temperature is too high, the metal soft magnetic powder core particles will stick together, increasing the eddy current loss of the magnetic core and destroying the insulating layer coating the surface of the metal soft magnetic powder core particles, thereby deteriorating the performance of the metal soft magnetic powder core. Within the above range, the internal stress of the metal soft magnetic powder core can be effectively eliminated.

[0042] In some embodiments, in order to prevent the induction coil from overheating due to current flowing through the induction coil and thus affecting the performance of the induction coil, circulating cooling water is continuously passed through the induction coil.

[0043] In order to further eliminate the internal stress of the metal soft magnetic powder core, the preferred time of the medium frequency induction heating treatment is 10 to 360 minutes (such as 10 minutes, 15 minutes, 20 minutes, 30 minutes, 50 minutes, 80 minutes, 100 minutes, 120 minutes, 150 minutes, 200 minutes, 240 minutes, 280 minutes, 300 minutes, 320 minutes, 360 minutes). If the time is too short, the internal stress of the metal soft magnetic powder core cannot be completely eliminated. If the time is too long, the internal stress of the metal soft magnetic powder core has been basically eliminated. Continuing to extend the time will not significantly increase the effect of eliminating the internal stress of the metal soft magnetic powder core. Within the above range, the internal stress of the metal soft magnetic powder core can be completely eliminated while shortening the time of the medium frequency induction heating treatment, thereby reducing costs and reducing energy waste.

[0044] In some embodiments, the above-mentioned medium frequency induction heating treatment is carried out under the protection of an inert gas. Preferably, the inert gas includes at least one of nitrogen, argon, and helium to avoid oxidation of the metal soft magnetic powder core when it comes into contact with air during the induction heating treatment, which is beneficial to improving the performance of the metal soft magnetic powder core.

[0045] In order to further improve the performance of the metal soft magnetic powder core and avoid damage to the insulating layer on the surface of the metal soft magnetic powder core particles due to long-term high temperature, which causes the performance of the metal soft magnetic powder core to deteriorate at high temperature, the metal soft magnetic powder core is quickly cooled after medium frequency induction heating treatment. The specific cooling method is not limited, including but not limited to air cooling and water cooling to quickly cool to room temperature. The time for rapid cooling to room temperature is 20 to 60 minutes.

[0046] In a second typical embodiment of the present application, a metal soft magnetic powder core is provided, which is obtained by the preparation method provided in the first typical embodiment. The metal soft magnetic powder core has high magnetic permeability and low loss.

[0047] The beneficial effects of the present application will be further illustrated below in combination with embodiments and comparative examples.

[0048] Example 1

[0049] This embodiment provides a metal soft magnetic powder core, and the preparation method thereof comprises the following steps:

[0050] (1) 500 mesh iron-nickel soft magnetic powder is fully mixed with 0.5wt% phosphoric acid for passivation, the passivated iron-nickel soft magnetic powder is fully mixed with 0.5wt% kaolin insulation and stirred for primary coating, and then 0.5wt% silicone resin is added and mixed evenly for secondary coating, the coated metal soft magnetic powder is fully mixed with 0.5wt% phenolic resin and 0.1wt% zinc stearate, and molded at a molding pressure of 1500MPa to prepare a Φ14mm*Φ8mm magnetic powder core sample ring.

[0051] (2) The magnetic powder core sample ring is placed in a medium frequency induction heating device for medium frequency induction heating treatment. Under nitrogen protection, electric current is passed for heating at a frequency of 0.5 kHz. The current is adjusted so that the heating temperature is 500°C. The medium frequency induction heating treatment time is 10 min. After the insulation is completed, the magnetic powder core sample ring is taken out and placed in the air for rapid cooling to room temperature to obtain a metal soft magnetic powder core.

[0052] Example 2

[0053] This embodiment provides a metal soft magnetic powder core, and the preparation method thereof comprises the following steps:

[0054] (1) 500 mesh iron-nickel soft magnetic powder was fully mixed with 0.2wt% phosphoric acid for passivation, the passivated iron-nickel soft magnetic powder was fully mixed with 0.8wt% kaolin insulation and stirred for primary coating, and then 0.5wt% silicone resin was added and mixed evenly for secondary coating, the coated metal soft magnetic powder was fully mixed with 1wt% phenolic resin and 0.5wt% zinc stearate, and molded at a molding pressure of 2000MPa to prepare a Φ14mm*Φ8mm magnetic powder core sample ring.

[0055] (2) The magnetic powder core sample ring is placed in a medium frequency induction heating device for medium frequency induction heating treatment. Under nitrogen protection, electric current is passed for heating at a frequency of 0.8 kHz. The current is adjusted so that the heating temperature is 600°C. The medium frequency induction heating treatment time is 10 min. After the insulation is completed, the magnetic powder core sample ring is taken out and placed in the air for rapid cooling to room temperature to obtain a metal soft magnetic powder core.

[0056] Example 3

[0057] This embodiment provides a metal soft magnetic powder core, and the preparation method thereof comprises the following steps:

[0058] (1) 500 mesh Sendust soft magnetic powder was mixed with 0.5wt% phosphoric acid for passivation, the passivated Sendust soft magnetic powder was mixed with 1wt% kaolin insulation and stirred for primary coating, and then 0.5wt% silicone resin was added and mixed evenly for secondary coating, the coated metal soft magnetic powder was mixed with 1wt% phenolic resin and 0.5wt% zinc stearate, and molded at a molding pressure of 1500MPa to prepare a Φ14mm*Φ8mm magnetic powder core sample ring.

[0059] (2) The magnetic powder core sample ring is placed in a medium frequency induction heating device for medium frequency induction heating treatment. Under nitrogen protection, electric current is passed for heating at a frequency of 0.5 kHz. The current is adjusted so that the heating temperature is 600°C. The medium frequency induction heating treatment time is 10 min. After the insulation is completed, the magnetic powder core sample ring is taken out and placed in the air for rapid cooling to room temperature to obtain a metal soft magnetic powder core.

[0060] Example 4

[0061] This embodiment provides a metal soft magnetic powder core, and the preparation method thereof comprises the following steps:

[0062] (1) 500 mesh Sendust soft magnetic powder was mixed with 0.5wt% phosphoric acid for passivation, the passivated Sendust soft magnetic powder was mixed with 1wt% kaolin insulation and stirred for the first coating, and then 0.5wt% silicone resin was added and mixed evenly for the second coating, the coated metal soft magnetic powder was mixed with 1.5wt% phenolic resin and 1wt% zinc stearate, and molded at a molding pressure of 2000MPa to prepare a Φ14mm*Φ8mm magnetic powder core sample ring.

[0063] (2) The magnetic powder core sample ring is placed in a medium frequency induction heating device for medium frequency induction heating treatment. Under nitrogen protection, electric current is passed for heating at a frequency of 0.5 kHz. The current is adjusted so that the heating temperature is 700°C. The medium frequency induction heating treatment time is 10 min. After the insulation is completed, the magnetic powder core sample ring is taken out and placed in the air for rapid cooling to room temperature to obtain a metal soft magnetic powder core.

[0064] Example 5

[0065] This embodiment provides a metal soft magnetic powder core, and the preparation method thereof comprises the following steps:

[0066] (1) 500 mesh iron silicon soft magnetic powder was fully mixed with 0.5wt% phosphoric acid for passivation, the passivated iron silicon soft magnetic powder was fully mixed with 1wt% kaolin insulation and stirred for the first coating, and then 0.5wt% silicone resin was added and mixed evenly for the second coating, the coated metal soft magnetic powder was fully mixed with 1.5wt% phenolic resin and 1wt% zinc stearate, and molded at a molding pressure of 2000MPa to prepare a Φ14mm*Φ8mm magnetic powder core sample ring.

[0067] (2) The magnetic powder core sample ring is placed in a medium frequency induction heating device for medium frequency induction heating treatment. Under nitrogen protection, electric current is passed for heating at a frequency of 1 kHz. The current is adjusted so that the heating temperature is 700°C. The medium frequency induction heating treatment time is 10 min. After the insulation is completed, the magnetic powder core sample ring is taken out and placed in the air for rapid cooling to room temperature to obtain a metal soft magnetic powder core.

[0068] Example 6

[0069] This embodiment provides a metal soft magnetic powder core, and the preparation method thereof comprises the following steps:

[0070] (1) 500 mesh iron silicon soft magnetic powder was fully mixed with 0.5wt% phosphoric acid for passivation, the passivated iron silicon soft magnetic powder was fully mixed with 1wt% kaolin insulation and stirred for the first coating, and then 0.8wt% silicone resin was added and mixed evenly for the second coating, the coated metal soft magnetic powder was fully mixed with 1.5wt% phenolic resin and 1wt% zinc stearate, and molded at a molding pressure of 2500MPa to prepare a Φ14mm*Φ8mm magnetic powder core sample ring.

[0071] (2) The magnetic powder core sample ring is placed in a medium frequency induction heating device for medium frequency induction heating treatment. Under nitrogen protection, electric current is passed for heating at a frequency of 1 kHz. The current is adjusted so that the heating temperature is 800°C. The medium frequency induction heating treatment time is 10 min. After the insulation is completed, the magnetic powder core sample ring is taken out and placed in the air for rapid cooling to room temperature to obtain a metal soft magnetic powder core.

[0072] Example 7

[0073] The difference between this embodiment and embodiment 2 is that the current frequency is 20 kHz.

[0074] Example 8

[0075] The difference between this embodiment and embodiment 2 is that the current frequency is 0.5 kHz.

[0076] Example 9

[0077] The difference between this embodiment and embodiment 2 is that the current frequency is 0.2 kHz.

[0078] Example 10

[0079] The difference between this embodiment and embodiment 2 is that the current frequency is 30 kHz.

[0080] Embodiment 11

[0081] The difference between this embodiment and embodiment 2 is that the current is adjusted so that the heating temperature is 900°C.

[0082] Example 12

[0083] The difference between this embodiment and embodiment 2 is that the current is adjusted so that the heating temperature is 500°C.

[0084] Embodiment 13

[0085] The difference between this embodiment and embodiment 2 is that the current is adjusted so that the heating temperature is 200°C.

[0086] Embodiment 14

[0087] The difference between this embodiment and embodiment 2 is that the current is adjusted so that the heating temperature is 1000°C.

[0088] Embodiment 15

[0089] The difference between this embodiment and embodiment 2 is that the medium frequency induction heating treatment time is 360 minutes.

[0090] Example 16

[0091] The difference between this embodiment and embodiment 2 is that the medium frequency induction heating treatment time is 40 minutes.

[0092] Embodiment 17

[0093] The difference between this embodiment and embodiment 2 is that the medium frequency induction heating treatment time is 120 minutes.

[0094] Embodiment 18

[0095] The difference between this embodiment and embodiment 2 is that the medium frequency induction heating treatment time is 5 minutes.

[0096] Embodiment 19

[0097] The difference between this embodiment and embodiment 2 is that the medium frequency induction heating treatment time is 400 minutes.

[0098] Comparative Example 1

[0099] This comparative example provides a metal soft magnetic powder core, and the preparation method thereof comprises the following steps:

[0100] (1) 500 mesh iron-nickel soft magnetic powder was fully mixed with 0.3wt% phosphoric acid for passivation, the passivated iron-nickel soft magnetic powder was fully mixed with 1wt% kaolin insulation and stirred for primary coating, and then 0.5wt% silicone resin was added and mixed evenly for secondary coating, the coated metal soft magnetic powder was fully mixed with 0.5wt% phenolic resin and xxwt% zinc stearate, and molded at a molding pressure of 1500MPa to prepare a Φ14*Φ8mm magnetic powder core sample ring.

[0101] (2) The magnetic powder core sample ring is placed in a tubular furnace, and nitrogen is introduced to heat it to 500°C and keep it warm for 10 minutes. After the insulation is completed, the magnetic powder core sample ring is cooled in the furnace to obtain a metal soft magnetic powder core.

[0102] Comparative Example 2

[0103] This comparative example provides a metal soft magnetic powder core, and the preparation method thereof comprises the following steps:

[0104] (1) 500 mesh Sendust soft magnetic powder was mixed with 0.3wt% phosphoric acid for passivation, the passivated Sendust soft magnetic powder was mixed with 1wt% kaolin insulation and stirred for primary coating, and then 0.5wt% silicone resin was added and mixed evenly for secondary coating, the coated metal soft magnetic powder was mixed with 1.0wt% phenolic resin and 0.1wt% zinc stearate, and molded at a molding pressure of 1500MPa to prepare a Φ14*Φ8mm magnetic powder core sample ring.

[0105] (2) The magnetic powder core sample ring is placed in a tubular furnace, and nitrogen is introduced to heat it to 600°C and keep it warm for 10 minutes. After the insulation is completed, the magnetic powder core sample ring is cooled in the furnace to obtain a metal soft magnetic powder core.

[0106] Comparative Example 3

[0107] This comparative example provides a metal soft magnetic powder core, and the preparation method thereof comprises the following steps:

[0108] (1) 500 mesh Sendust soft magnetic powder was mixed with 0.3wt% phosphoric acid for passivation, the passivated Sendust soft magnetic powder was mixed with 1wt% kaolin insulation and stirred for primary coating, and then 0.5wt% silicone resin was added and mixed evenly for secondary coating, the coated metal soft magnetic powder was mixed with 1.0wt% phenolic resin and 0.5wt% zinc stearate, and molded at a molding pressure of 1500MPa to prepare a Φ14*Φ8mm magnetic powder core sample ring.

[0109] (2) The magnetic powder core sample ring is placed in a tubular furnace, and nitrogen is introduced to heat it to 700°C and keep it warm for 10 minutes. After the insulation is completed, the magnetic powder core sample ring is cooled in the furnace to obtain a metal soft magnetic powder core.

[0110] Comparative Example 4

[0111] This comparative example provides a metal soft magnetic powder core, and the preparation method thereof comprises the following steps:

[0112] (1) 500 mesh iron silicon soft magnetic powder is fully mixed with 0.3wt% phosphoric acid for passivation, the passivated iron silicon soft magnetic powder is mixed with 1wt% kaolin insulation and stirred for primary coating, and then 0.5wt% silicone resin is added and mixed evenly for secondary coating, the coated metal soft magnetic powder is fully mixed with 1.0wt% phenolic resin and 0.5wt% zinc stearate, and molded at a molding pressure of 1500MPa to prepare a Φ14*Φ8mm magnetic powder core sample ring.

[0113] (2) The magnetic powder core sample ring is placed in a tubular furnace, and nitrogen is introduced to heat it to 700°C and keep it warm for 10 minutes. After the insulation is completed, the magnetic powder core sample ring is cooled in the furnace to obtain a metal soft magnetic powder core.

[0114] Test Example 1

[0115] The metal soft magnetic powder cores prepared in the examples and comparative examples were tested for magnetic permeability, loss Pcv (core loss) (50kHz, 100mT), and loss Pcv (core loss) (100kHz, 100mT). The results are shown in Table 1 below.

[0116] in:

[0117] (1) Magnetic permeability test:

[0118] A copper wire with a diameter of 0.4 mm was used to evenly wind 30 turns on the metal soft magnetic powder cores prepared in the embodiment and the comparative example, respectively. The test conditions were 100 kHz, 1 V, and 25° C.;

[0119] (2) Loss Pcv (50kHz, 100mT) (100kHz, 100mT) test:

[0120] A copper wire with a diameter of 0.4 mm was used to evenly wind 30*5 turns on the metal soft magnetic powder cores prepared in the embodiment and the comparative example, respectively. The test conditions were 50 kHz, 100 mT, 25°C and 100 kHz, 100 mT, 25°C.

[0121] Table 1

[0122]

[0123]

[0124] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: the preparation method of the metal soft magnetic powder core provided by the present application can not only quickly eliminate the internal stress of the metal soft magnetic powder core by adopting medium frequency induction heating treatment, but also does not damage the resistance insulation layer, thereby reducing the hysteresis loss and eddy current loss under high frequency. The preparation method has a simple preparation process, a short processing time, avoids high temperature processing, and can produce a metal soft magnetic powder core with high magnetic permeability and low loss.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a metal soft magnetic powder core, characterized in that: The preparation method comprises: Step S1, insulating and coating the metal soft magnetic powder first, and then pressing and molding it to obtain a magnetic powder core sample ring; Step S2, subjecting the magnetic powder core sample ring to medium frequency induction heating treatment to obtain the metal soft magnetic powder core.

2. The method for preparing the metal soft magnetic powder core according to claim 1, characterized in that: In step S2, the frequency of the medium frequency induction heating treatment is 0.5 to 20 kHz; And / or, the temperature of the medium frequency induction heating treatment is 500-900°C; And / or, the medium frequency induction heating treatment time is 10 to 360 minutes.

3. The method for preparing the metal soft magnetic powder core according to claim 1, characterized in that: In the step S2, the medium frequency induction heating treatment is performed under the protection of an inert gas, and preferably the inert gas includes at least one of nitrogen, argon and helium.

4. The method for preparing the metal soft magnetic powder core according to claim 1, characterized in that: In the step S1, the pressing pressure is 1000 MPa to 2500 MPa.

5. The method for preparing the metal soft magnetic powder core according to claim 1, characterized in that: In the step S1, the particle size of the metal soft magnetic powder is 200-1000 meshes.

6. The method for preparing the metal soft magnetic powder core according to claim 1, characterized in that: In the step S1, the material of the metal soft magnetic powder includes at least one of sendustine, iron-nickel, iron-silicon, iron-nickel-molybdenum, and amorphous nanocrystals.

7. The method for preparing a metal soft magnetic powder core according to any one of claims 1 to 6, characterized in that: The step S1 comprises: Step S11, mixing the metal soft magnetic powder with an acidic solution for passivation treatment, then adding an inorganic insulating agent for primary coating, and then adding a silicone resin for secondary coating to obtain coated metal soft magnetic powder; Step S12, mixing the coated metal soft magnetic powder with a binder and a release agent, and performing compression molding to obtain the magnetic powder core sample ring.

8. The method for preparing the metal soft magnetic powder core according to claim 7, characterized in that: In the step S11, the acidic substance includes at least one of phosphoric acid, oxalic acid, and boric acid, preferably phosphoric acid; the inorganic insulating agent includes at least one of silicon oxide, aluminum oxide, magnesium oxide, kaolin, mica powder, and diatomaceous earth; Preferably, based on the metal soft magnetic powder, the mass content of the acidic substance is 0.1-0.5%, the mass content of the inorganic insulating agent is 0.8-1.5%, and the mass content of the silicone resin is 0.2-0.5%.

9. The method for preparing the metal soft magnetic powder core according to claim 7, characterized in that: In the step S12, the adhesive includes at least one of polyvinyl alcohol, polyurethane, epoxy resin, and polyacrylate; the release agent includes at least one of zinc stearate / magnesium / aluminum, graphite, and talc; Preferably, the mass ratio of the binder to the metal soft magnetic powder is (0.5-2.5): 100; Preferably, the mass ratio of the release agent to the metal soft magnetic powder is (0.1-1.5):

100.

10. A metal soft magnetic powder core, characterized in that: The metal soft magnetic powder core is prepared according to the preparation method described in any one of claims 1 to 9.

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