JP2005303006A - Method of manufacturing dust core and dust core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing dust core by which the hysteresis loss and eddy current loss can be reduced, and to provide a dust core. <P>SOLUTION: The method of manufacturing dust core includes a step (S1) of producing mixed powder by mixing composite magnetic particles 30a obtained by coating first metal particles 10a containing Fe as the main component with first insulating coating films 20a and having a saturation magnetic flux density Bs of ≥1.5 T and composite magnetic particles 30b obtained by coating second metal particles 10b containing Fe as the main component and one or more kinds of elements selected out of a group composed of Al, Si, Cr, Ni, and Co with second insulating coating films 20b with each other. The method also includes a step (S2) of producing a molded body by press-molding the mixed powder and a step (S3) of heat-treating the molded body at a temperature of 500°C-900°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dust core manufacturing method and a dust core, and more particularly to a dust core manufacturing method and a dust core capable of reducing hysteresis loss and eddy current loss.

  A dust core made of a soft magnetic material is used in an electric device having a solenoid valve, a motor, a power supply circuit, or the like. This soft magnetic material is composed of a plurality of composite magnetic particles, and the composite magnetic particles have metal magnetic particles and a glass-like insulating coating covering the surface thereof. The soft magnetic material is required to have a magnetic characteristic that can obtain a large magnetic flux density by applying a small magnetic field and can react sensitively to a magnetic field change from the outside.

  When this dust core is used in an alternating magnetic field, an energy loss called iron loss occurs. This iron loss is represented by the sum of hysteresis loss and eddy current loss. Hysteresis loss refers to energy loss caused by energy required to change the magnetic flux density of a soft magnetic material. Since the hysteresis loss is proportional to the operating frequency, it becomes predominant mainly in the low frequency region. Further, the eddy current loss referred to here means energy loss caused by eddy current flowing mainly between the metal magnetic particles constituting the soft magnetic material. Since the eddy current loss is proportional to the square of the operating frequency, it becomes dominant mainly in the high frequency region.

  The dust core is required to have magnetic characteristics that reduce the occurrence of iron loss. In order to realize this, it is necessary to improve the permeability μ of the constituent particles and reduce the coercivity Hc. It is also necessary to increase the electrical resistivity ρ as a dust core. Furthermore, when a large excitation magnetic flux density is required during operation, it is important to increase the saturation magnetic flux density Bs of the constituent particles and the dust core.

  In order to reduce the hysteresis loss among the iron loss of the dust core, the coercive force Hc of the dust core can be reduced by removing the distortion and dislocation in the metal magnetic particles to facilitate the domain wall movement. That's fine. In order to sufficiently remove strain and dislocation in the metal magnetic particles, it is necessary to heat-treat the soft magnetic material at a high temperature of 400 ° C. or higher.

  However, since the heat resistance of the insulating film is low, if the soft magnetic material is heat-treated at a high temperature of 400 ° C. or higher, the insulating film is deteriorated by heat. For this reason, when heat treatment is performed to reduce the hysteresis loss, there is a problem that the electrical resistivity ρ of the soft magnetic material is lowered and the eddy current loss is increased. Particularly, in recent years, there has been a demand for reduction in size, efficiency, and increase in output of electrical equipment. In order to satisfy these demands, it is necessary to use electrical equipment in a high frequency region. If the eddy current loss in the high frequency region becomes large, it will hinder the miniaturization, efficiency, and high output of the electrical equipment.

Therefore, a technique capable of improving the heat resistance of the insulating coating to some extent is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-272911 (Patent Document 1). Patent Document 1 discloses a soft magnetic material made of composite magnetic particles having an aluminum phosphate-based insulating coating with high heat resistance. In Patent Document 1, a soft magnetic material is manufactured by the following method. First, an insulating coating aqueous solution containing a phosphate containing aluminum and a heavy chromium salt containing potassium or the like is sprayed onto the iron powder. Next, the iron powder sprayed with the insulating coating aqueous solution is held at 300 ° C. for 30 minutes and held at 100 ° C. for 60 minutes. Thereby, the insulating coating formed on the iron powder is dried. Next, the iron powder on which the insulating coating is formed is pressure-molded and heat-treated after the pressure-molding to complete the soft magnetic material.
JP 2003-272911 A

  However, the aluminum phosphate insulating film disclosed in Patent Document 1 still has insufficient heat resistance. In order to sufficiently remove the distortion and dislocation of the metal magnetic particles, it is necessary to heat-treat the soft magnetic material at a high temperature of 500 ° C to 800 ° C. When metal magnetic particles having an aluminum phosphate-based insulating coating are heat-treated at such a high temperature, the aluminum phosphate-based insulating coating is deteriorated. As a result, there is a problem that the electrical resistivity ρ of the soft magnetic material is lowered and the eddy current loss is increased.

  Accordingly, an object of the present invention is to provide a dust core manufacturing method and a dust core capable of reducing hysteresis loss and eddy current loss.

  The manufacturing method of the dust core of the present invention includes the following steps. A first insulating film is formed on the surface of the first metal particle containing Fe (iron) as a main component, the first particle having a saturation magnetic flux density Bs of 1.5 T or more, and Fe as a main component. And on the surface of the second metal particle containing at least one element selected from the group consisting of Al (aluminum), Si (silicon), Cr (chromium), Ni (nickel), and Co (cobalt). A mixed powder is produced by mixing the second particles in the form in which the insulating coating is formed. The mixed powder is pressure molded to produce a molded body. The molded body is heat-treated at 500 ° C. or higher and 900 ° C. or lower.

  According to the method for manufacturing a dust core of the present invention, the speed of mutual diffusion between the atoms contained in the second insulating film and the second metal particles is determined by the mutual diffusion between the atoms contained in the insulating film and the iron atoms. Slower than the rate of diffusion. As described above, since atoms contained in the second insulating film are difficult to diffuse into the second metal particles, the deterioration of the second insulating film does not proceed. Thereby, even if it heat-processes at the temperature (500 degreeC or more) in which a 1st insulating film deteriorates, the insulation between 1st metal particles is maintained by the 2nd particle | grains intervening between 1st particles. As a result, the electrical resistivity ρ of the dust core can be kept high, and hysteresis loss and eddy current loss can be reduced. In addition, by performing heat treatment at 900 ° C. or less, the atoms contained in the second insulating film diffuse into the second metal particles, so that the second insulating film disappears or the concentration of impurities in the second metal particles increases. Can be deterred.

  Preferably, in the manufacturing method, when preparing the mixed powder, the first insulating film is formed on the first metal particles to form the first particles, and the second insulating film is formed on the second metal particles. Two particles are produced. Thereafter, the first particles and the second particles are mixed.

  Thereby, even when the particle size of the first metal particle and the particle size of the second metal particle are greatly different, an insulating film having an appropriate film thickness can be uniformly formed in each particle.

  Preferably, in the manufacturing method, the particle size of the first particles is larger than the particle size of the second particles. Thereby, it becomes easy to become a structure that the 2nd particle enters between the 1st particles. For this reason, the insulation between the first metal particles is easily maintained by the second particles.

  Preferably in the said manufacturing method, the ratio of the 2nd particle | grains in mixed powder is 20 volume% or more and 50 volume% or less. Thereby, hysteresis loss and eddy current loss can be further reduced.

  Preferably, in the above manufacturing method, at least one selected from the group consisting of P (phosphorus), Si, Al, Cr, Ti (titanium), and Zr (zirconia) is used for either the first insulating film or the second insulating film. It consists of a compound containing the above elements.

  Since P, Si, Al, Cr, Ti, and Zr are excellent in insulation, eddy currents flowing between metal magnetic particles can be more effectively suppressed.

  Preferably, in the above production method, when preparing the mixed powder, at least one resin selected from the group consisting of phenol resin, polyethylene resin, silicone resin, polyimide resin, epoxy resin, polyamide resin, and acrylic resin is further added. Mix.

  As a result, the resin bends between the first particles and the second particles in response to the stress during the pressure molding, thereby functioning as a lubricant between the first particles and the second particles. Therefore, since the resin functions as a binder, the moldability of the dust core is improved. Moreover, it can prevent that an insulating film is damaged by shaping | molding.

  By manufacturing the dust core by the above manufacturing method, a dust core having an iron loss of 120 W / kg or less when the excitation magnetic flux density is 1 T and the frequency of the alternating magnetic field is 1000 Hz can be obtained.

  In the present specification, “mainly comprising Fe” means that the proportion of Fe in the first particles or the second particles is 50% by mass or more.

  According to the method for manufacturing a dust core of the present invention, the speed of mutual diffusion between the atoms contained in the second insulating film and the second metal particles is determined by the mutual diffusion between the atoms contained in the insulating film and the iron atoms. Slower than the rate of diffusion. As described above, since atoms contained in the second insulating film are difficult to diffuse into the second metal particles, the deterioration of the second insulating film does not proceed. Thereby, even if it heat-processes at the temperature (500 degreeC or more) in which a 1st insulating film deteriorates, the insulation between 1st metal particles is maintained by the 2nd particle | grains intervening between 1st particles. As a result, the electrical resistivity ρ of the dust core can be kept high, and hysteresis loss and eddy current loss can be reduced. In addition, by performing heat treatment at 900 ° C. or less, the atoms contained in the second insulating film diffuse into the second metal particles, so that the second insulating film disappears or the concentration of impurities in the second metal particles increases. Can be deterred.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an enlarged schematic view showing a dust core in one embodiment of the present invention.

  Referring to FIG. 1, the dust core of the present embodiment is composed of a plurality of composite magnetic particles 30, and the composite magnetic particles 30 are composed of two types of composite magnetic particles 30a and 30b. The composite magnetic particle 30a as the first particle has a first metal particle 10a and a first insulating coating 20a formed on the surface of the first metal particle 10a. The first metal particles 10a are mainly composed of Fe, and are made of, for example, pure iron, Fe, an Fe—Si alloy, or an Fe—Co alloy. In addition, it is preferable that Si is an addition amount of 7% by volume or less in the Fe—Si based alloy, and it is preferable that Co is an addition amount of up to 50% in the Fe—Co based alloy. All of these materials have a saturation magnetic flux density Bs of 1.5 T or more. The composite magnetic particle 30b as the second particle includes the second metal particle 10b and the second insulating coating 20b formed on the surface of the second metal particle 10b. The second metal particle 10b contains Fe as a main component and contains at least one element selected from the group consisting of Al, Si, Cr, Ni, and Co. Second metal particle 10b is made of, for example, sendust or electromagnetic stainless powder. An organic substance 40 is interposed between each of the plurality of composite magnetic particles 30. Each of the plurality of composite magnetic particles 30 is joined by the organic material 40 or joined by meshing the unevenness of the composite magnetic particle 30.

  The average particle diameter of the first metal particles 10a is preferably 5 μm or more and 300 μm or less. When the average particle diameter of the first metal particles 10a is 5 μm or more, iron is not easily oxidized, so that it is possible to suppress a decrease in magnetic properties of the soft magnetic material. Moreover, when the average particle diameter of the 1st metal particle 10a is 300 micrometers or less, it can suppress that the compressibility of mixed powder falls at the time of the subsequent shaping | molding process. Thereby, it can prevent that the density of the molded object obtained by the formation process does not fall, and handling becomes difficult. The average particle size of the composite magnetic particle 30a is larger than the average particle size of the composite magnetic particle 30b.

  The average particle diameter means the particle diameter of particles in which the sum of masses from the smaller particle diameter reaches 50% of the total mass in the histogram of particle diameters measured by the sieving method, that is, 50% particle diameter D. .

  The first insulating coating 20a and the second insulating coating 20b function as an insulating layer between the first metal particles 10a and the second metal particles 10b. By covering the first metal particles 10a with the first insulating coating 20a and covering the second metal particles 10b with the second insulating coating 20b, the electrical resistivity ρ of the dust core can be increased. Thereby, it can suppress that an eddy current flows between the 1st metal particle 10a and the 2nd metal particle 10b, and can reduce the iron loss resulting from the eddy current loss of a powder magnetic core.

  The thickness of the first insulating coating 20a and the second insulating coating 20b is preferably 0.005 μm or more and 20 μm or less. By setting the thicknesses of the first insulating film 20a and the second insulating film 20b to 0.005 μm or more, energy loss due to eddy current can be effectively suppressed. Further, by setting the thicknesses of the first insulating film 20a and the second insulating film 20b to 20 μm or less, the ratio of the first insulating film 20a and the second insulating film 20b in the dust core does not become too large. For this reason, it can prevent that the magnetic flux density of a powder magnetic core falls remarkably.

  The organic substance 40 is made of, for example, at least one resin selected from the group consisting of phenol resin, polyethylene resin, silicone resin, polyimide resin, epoxy resin, polyamide resin, and acrylic resin. In the present embodiment, the case where the organic substance 40 is interposed between each of the plurality of composite magnetic particles 30 has been described, but the organic substance 40 may be omitted.

  Next, the manufacturing method of the soft magnetic material in this Embodiment is demonstrated.

  FIG. 2 is a process diagram showing a method for producing a soft magnetic material according to an embodiment of the present invention.

  Referring to FIG. 2, first metal particles 10 a that contain Fe as a main component and are made of, for example, pure iron, Fe, a Fe—Si alloy, or a Fe—Co alloy are prepared. And this 1st metal particle 10a is heat-processed at the temperature of 400 degreeC or more and less than 900 degreeC. The heat treatment temperature is more preferably 700 ° C. or higher and lower than 900 ° C. Many strains (dislocations and defects) exist in the first metal particles 10a before the heat treatment. This distortion can be reduced by performing a heat treatment on the first metal particles 10a. Next, the first insulating film 20a is formed on the surface of the first metal particle 10a by, for example, immersing the first metal particle 10a in an aqueous solution in which the components of the first insulating film 20a are dissolved, and then drying it (see FIG. Step S1a). Thereby, the composite magnetic particle 30a is obtained.

  On the other hand, a second metal particle 10b containing Fe as a main component and containing at least one element selected from the group consisting of Al, Si, Cr, Ni, and Co is prepared. And it heat-processes by the method similar to the 1st metal particle 10a. Next, the second insulating film 20b is formed on the surface of the second metal particle 10b by the same method as that for the first metal particle 10a (step S1b). Thereby, the composite magnetic particle 30b is obtained.

  Each of the first insulating coating 20a and the second insulating coating 20b is preferably made of a compound containing at least one element selected from the group consisting of P, Si, Al, Cr, Ti, and Zr. For example, it consists of an insulator containing an aluminum phosphate compound and a calcium phosphate compound. When the second metal particles 10b are made of Sendust, an Al oxide film contained in Sendust may be used as the second insulating coating 20b. When the second metal particles 10b are made of electromagnetic stainless steel, a Cr oxide film contained in the electromagnetic stainless steel may be used as the second insulating coating 20b.

  Next, the composite magnetic particle 30a, the composite magnetic particle 30b, and the organic substance 40 are mixed (step S1c). The organic substance 40 is made of, for example, at least one resin selected from the group consisting of phenol resin, polyethylene resin, silicone resin, polyimide resin, epoxy resin, polyamide resin, or acrylic resin. The ratio of the composite magnetic particles 30b in the mixed powder is preferably 20% by volume or more and 50% by volume or less. The mixing method is not particularly limited. For example, mechanical alloying method, vibration ball mill, planetary ball mill, mechanofusion, coprecipitation method, chemical vapor deposition method (CVD method), physical vapor deposition method (PVD method), plating Any of the method, sputtering method, vapor deposition method or sol-gel method can be used. The above steps S1a to S3a are the step of producing the mixed powder (step S1).

  Thus, the process of forming the insulating coating 20a on the surface of the first metal particle 10a (step S1a) and the process of forming the insulating coating 20b on the second metal particle 10b (step S1b) are performed separately, and then By mixing the composite magnetic particle 30a and the composite magnetic particle 30b (step S1c), even when the particle diameter of the first metal particle 10a and the particle diameter of the second metal particle 10b are greatly different, a uniform insulating coating is formed. Each particle can be formed.

  Next, the obtained mixed powder is put into a mold, and pressure-molded at a pressure of, for example, 980 MPa or more (step S2). Thereby, a mixed powder is compressed and a molded object is obtained. The atmosphere for pressure molding is preferably an inert gas atmosphere or a reduced pressure atmosphere. In this case, the mixed powder can be prevented from being oxidized by oxygen in the atmosphere.

  During the pressure molding, the organic substance 40 functions as a buffer material between the composite magnetic particles 30. This prevents the first insulating coating 20a and the second insulating coating 20b from being destroyed by the contact between the composite magnetic particles 30.

  Next, the molded body obtained by pressure molding is heat-treated at 500 ° C. or higher and 900 ° C. or lower (step S3). As described above, in the manufacturing method of the present embodiment, the molded body is heat-treated at a high temperature of 500 ° C. or higher, so that distortion generated in the molded body during pressure molding can be sufficiently removed. Here, the thermal decomposition temperature of the first insulating coating 20a and the second insulating coating 20b is, for example, 500 ° C. in the case of a phosphate insulating coating. However, in the manufacturing method of the present embodiment, the insulation between the first metal particles 10b can be maintained even if heat treatment is performed at 500 ° C. or higher. This will be described below.

  In the composite magnetic particle 30b, the second metal particle 10b is made of a material that hardly diffuses with the constituent particles of the second insulating coating 20b. For this reason, the atoms contained in the second insulating coating 20b during the heat treatment are less likely to diffuse into the second metal particles 10b. As a result, the atoms of the second insulating film stay on the surface of the second metal particle, and the concentration of atoms of the second insulating film increases on the surface of the second metal particle. Then, the deterioration of the second insulating film does not progress further due to chemical equilibrium. As described above, since the second insulating coating 20b is not easily deteriorated even if heat treatment is performed at 500 ° C. or higher, the insulation between the first metal particles 10a is maintained by the composite magnetic particles 30b interposed between the composite magnetic particles 30a. be able to.

  The molded body shown in FIG. 1 is completed by the steps described above.

  In the present embodiment, the case where the composite magnetic particles 30a, the composite magnetic particles 30b, and the organic substance 40 are mixed (step S1c) has been described. However, the mixing of the organic substance 40 with the composite magnetic particles 30a and 30b is essential. Instead of the above step, the pressure molding (step S2) may be carried out with only the composite magnetic particles 30a and 30b without mixing the organic substance 40.

  In the present embodiment, the step of forming first insulating coating 20a on the surface of first metal particle 10a and the step of forming second insulating coating 20a on second metal particle 10b are performed separately. However, the present invention is not limited to such a case. After the first metal particles 10a and the second metal particles 10b are mixed, the first metal particles 10a and the second metal particles 10b are mixed. Each of the first insulating coating 20a and the second insulating coating 20b may be simultaneously formed on each of the two. Thereby, a manufacturing process can be simplified.

  Further, in the present embodiment, a method for forming the first insulating coating 20a by immersing the first metal particles 10a in an aqueous solution in which the components of the first insulating coating 20a are dissolved is shown. It is not limited to such a case, The method of forming the 1st insulating film 20a on the surface of the 1st metal particle 10a is arbitrary. Further, in the present embodiment, the case where the first insulating coating 20a and the second insulating coating 20b are insulators including an aluminum phosphate compound and a calcium phosphate compound has been described. In addition, an insulating coating made of an oxide insulator such as iron phosphate, manganese phosphate, zinc phosphate, calcium phosphate, aluminum phosphate, silicon oxide, titanium oxide, chromium oxide, aluminum oxide, or zirconium oxide may be formed. .

  The manufacturing method of the dust core of the present embodiment includes the following steps. The first insulating film 20a is formed on the surface of the first metal particle 10a containing Fe as a main component, and the composite magnetic particle 30a having a saturation magnetic flux density Bs of 1.5 T or more, and Fe as a main component. And a composite magnetic particle 30b in which a second insulating coating 20b is formed on the surface of the second metal particle 10b containing at least one element selected from the group consisting of Al, Si, Cr, Ni, and Co; To produce a mixed powder (step S1). The mixed powder is pressure-molded to produce a compact (step S2). The molded body is heat-treated at 500 ° C. or higher and 900 ° C. or lower (step S3).

  According to the method for manufacturing a powder magnetic core of the present embodiment, the speed of interdiffusion between the atoms contained in the second insulating coating 20b and the second metal particles 10b is the same as that of the atoms contained in the second insulating coating 20b. Slower than the rate of interdiffusion between iron atoms. As described above, atoms contained in the second insulating coating 20b are less likely to diffuse into the second metal particles 10b, so that the deterioration of the second insulating coating 20b does not proceed. Thereby, even if heat treatment is performed at a temperature (500 ° C. or higher) at which the first insulating coating 20a deteriorates, the insulation between the first metal particles 10a is maintained by the composite magnetic particles 30b interposed between the composite magnetic particles 30a. Be drunk. As a result, the electrical resistivity ρ of the dust core can be kept high, and hysteresis loss and eddy current loss can be reduced. Further, by performing a heat treatment at 900 ° C. or less, the atoms contained in the second insulating film 20b diffuse into the second metal particles 10b, so that the second insulating film 20b deteriorates or impurities in the second metal particles 10b. An increase in the concentration of can be suppressed.

  Preferably, in the manufacturing method described above, when preparing the mixed powder (step S1), the first insulating film 20a is formed on the first metal particle 10a to produce the composite magnetic particle 30a (step S1a), and the second metal The second insulating coating 20b is formed on the particle 10b to produce the composite magnetic particle 30b (step S1b). Thereafter, the composite magnetic particle 30a and the composite magnetic particle 30b are mixed (step S1c).

  Thereby, even when the particle diameter of the first metal particles 10a and the particle diameter of the second metal particles 10b are greatly different, the insulating coatings 20a and 20b having appropriate film thicknesses can be uniformly formed in the respective particles. .

  Preferably, in the above manufacturing method, the particle size of the composite magnetic particle 30a is larger than the particle size of the composite magnetic particle 30b. Thereby, it becomes easy to become a structure that the composite magnetic particle 30b enters between the composite magnetic particles 30a. For this reason, the insulation between the first metal particles 10a is easily maintained by the composite magnetic particles 30b.

  In the above production method, the ratio of the composite magnetic particles 30b in the mixed powder is preferably 20% by volume or more and 50% by volume or less. Thereby, hysteresis loss and eddy current loss can be further reduced.

  Preferably, in the manufacturing method, either the first insulating coating 20a or the second insulating coating 20b is made of a compound containing at least one element selected from the group consisting of P, Si, Al, Cr, Ti, and Zr. It has become.

  Since P, Si, Al, Cr, Ti, and Zr are excellent in insulation, the eddy current flowing between the metal magnetic particles 30 can be more effectively suppressed.

  Preferably, in the above manufacturing method, when the composite magnetic particles 30a and the composite magnetic particles 30b are mixed (step S1c), the composite magnetic particles 30a are composed of a phenol resin, a polyethylene resin, a silicone resin, a polyimide resin, an epoxy resin, a polyamide resin, and an acrylic resin. At least one organic material 40 selected from the group is further mixed.

  As a result, the organic substance 40 bends between the composite magnetic particle 30a and the composite magnetic particle 30b in response to the stress at the time of pressure molding so as to function as a lubricant between the composite magnetic particle 30a and the composite magnetic particle 30b. Become. Therefore, since the organic substance 40 functions as a binder, the moldability of the dust core is improved. Moreover, it can prevent that the 1st insulating coating 20a and the 2nd insulating coating 20b are damaged by shaping | molding.

  Examples of the present invention will be described below.

ABC100.30 made by Hennegas, whose purity of iron is 99.8% or more is prepared as the first metal particles 10a, and an insulating coating 20a made of iron phosphate is formed on the surface of the iron particles by a chemical conversion treatment method. A powder made of the composite magnetic particles 30a was prepared. In addition, DAP410L made by Daido Special Steel Co., Ltd., which is an electromagnetic stainless steel powder, is prepared as the second metal particles 10b, and an insulating coating 20b made of iron phosphate is formed on the surface of the electromagnetic stainless steel particles by a chemical conversion treatment method. B powder consisting of particles 30b was prepared. Next, the ratio of B powder to the whole is changed in the range of 0% by volume to 100% by volume, A powder, B powder, and 0.1% by mass of added resin are mixed, and the mixed powder is obtained. Produced. Next, the mixed powder was pressure-molded at a pressure of 7 to 15 t / cm ² (686 to 1470 MPa) to produce a molded body. Next, the compact was heat-treated in a temperature range of 300 ° C. to 1000 ° C. in a nitrogen stream atmosphere to produce a dust core. The iron loss of the obtained dust core was measured. The results are shown in Table 1. In Table 1, W represents iron loss, Wh represents hysteresis loss, and We represents eddy current loss. The units of W, Wh, and We are all W / kg.

  As shown in Table 1, heat treatment was performed at a temperature of 500 ° C. or higher than the hysteresis loss Wh when samples 2 to 20 prepared by mixing A powder and B powder were heat-treated at a temperature of less than 500 ° C. In this case, the hysteresis loss Wh is lower. For example, the hysteresis loss Wh when the sample 4 is heat-treated at a temperature of 400 ° C. is 114 W / kg, whereas the hysteresis loss Wh when the sample 4 is heat-treated at 500 ° C. is 86 W / kg. It is lower when heat-treated at ℃. On the other hand, the eddy current loss We when the samples 2 to 20 are heat-treated at a temperature higher than 900 ° C. is lower than the eddy current loss We when heat-treated at a temperature of 900 ° C. or lower. For example, the eddy current loss We when the sample 7 is heat-treated at a temperature of 1000 ° C. is 1976 W / kg, whereas the eddy current loss We when the sample 7 is heat-treated at a temperature of 900 ° C. is 244 W / kg. The eddy current loss We when the heat treatment is performed at a temperature of 900 ° C. is lower. Thereby, it turns out that the hysteresis loss Wh and the eddy current loss We can be reduced by heat-treating at 500 ° C. or more and 900 ° C. or less.

  Moreover, the eddy current loss We of sample 1 produced only with A powder and the eddy current loss We of samples 2 to 20 produced by mixing A powder and B powder were compared, and the eddy currents of samples 2 to 20 were compared. The current loss We is lower than the value of the eddy current loss We of the sample 1 when heat-treated at any temperature of 300 ° C. to 1000 ° C. In particular, the eddy current loss We of Samples 5 to 11 produced by mixing B powder at a ratio of 20 volume% or more and 50 volume% or less is even lower. For example, when the heat treatment is performed at a temperature of 700 ° C., the eddy current loss We of the sample 1 is 1537 W / kg, whereas the eddy current loss We of the sample 2 is 1395 W / kg. Is lower. Furthermore, the eddy current loss We of the sample 11 is 32 W / kg, and the sample 11 is even lower. Therefore, it turns out that eddy current loss We can be reduced by mixing powder B and producing a powder magnetic core. Moreover, it turns out that the eddy current loss We can be further reduced by making the ratio of B powder in mixed powder 20 volume% or more.

  Furthermore, hysteresis loss Wh of samples 5 to 11 prepared by mixing B powder at a ratio of 20% by volume or more and 50% by volume or less, and samples 12 to 21 prepared by mixing B powder at a ratio of 55% by volume or more. The hysteresis loss Wh of the samples 5 to 11 is lower than the hysteresis loss Wh of the samples 12 to 21 when heat-treated at any temperature of 300 ° C. to 1000 ° C. This is because AC magnetic characteristics such as coercive force Hc decrease as the amount of electromagnetic stainless steel powder added increases. Therefore, it can be seen that the hysteresis loss Wh as well as the eddy current loss We can be reduced by setting the ratio of the B powder in the mixed powder to 20 volume% or more and 50 volume% or less.

  When sample 6 prepared by mixing B powder at a rate of 25% by volume is heat-treated at a temperature of 600 ° C., the iron loss is 105 W / kg, and sample 6 is heat-treated at a temperature of 700 ° C. The iron loss is 102 W / kg. Further, when sample 7 prepared by mixing B powder at a ratio of 30% by volume was heat-treated at a temperature of 700 ° C., the iron loss was 111 W / kg, and sample 7 was heat-treated at a temperature of 800 ° C. In this case, the iron loss is 114 W / kg. Furthermore, when the sample 8 prepared by mixing B powder at a ratio of 35% by volume is heat-treated at a temperature of 700 ° C., the iron loss is 116 W / kg. Therefore, it can be seen that the iron loss of the obtained dust core becomes 120 W / kg or less by producing the dust core under these conditions.

  The embodiments and examples disclosed above are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims. .

It is a schematic diagram which expands and shows the powder magnetic core in one embodiment of this invention. It is process drawing which shows the manufacturing method of the soft-magnetic material in one embodiment of this invention.

Explanation of symbols

  10a, 10b metal particles, 20a, 20b insulating coating, 30, 30a, 30b composite magnetic particles, 40 organic matter.

Claims (7)

A first particle having a first insulating film formed on the surface of the first metal particle containing Fe as a main component, the saturation magnetic flux density Bs being 1.5 T or more;
A second insulating film formed on the surface of the second metal particle containing Fe as a main component and containing at least one element selected from the group consisting of Al, Si, Cr, Ni, and Co. Producing a mixed powder in which particles are mixed;
A step of pressure-molding the mixed powder to produce a molded body;
And a step of heat-treating the molded body at 500 ° C. or higher and 900 ° C. or lower. The step of producing the mixed powder includes:
Forming the first insulating film on the first metal particles to produce the first particles;
Forming the second insulating film on the second metal particles to produce the second particles;
2. The pressure according to claim 1, comprising a step of mixing the first particles and the second particles after the step of producing the first particles and the step of producing the second particles. Manufacturing method of a powder magnetic core.   3. The method of manufacturing a dust core according to claim 1, wherein an average particle size of the first particles is larger than an average particle size of the second particles. 4.   The method for producing a dust core according to any one of claims 1 to 3, wherein a ratio of the second particles in the mixed powder is 20% by volume or more and 50% by volume or less.   Either the first insulating film or the second insulating film is made of a compound containing at least one element selected from the group consisting of P, Si, Al, Cr, Ti, and Zr. The manufacturing method of the powder magnetic core in any one of Claims 1-4.   In the step of preparing the mixed powder, at least one resin selected from the group consisting of a phenol resin, a polyethylene resin, a silicone resin, a polyimide resin, an epoxy resin, a polyamide resin, and an acrylic resin is further mixed. The manufacturing method of the powder magnetic core in any one of Claims 1-5.   A powder magnetic core manufactured by the manufacturing method according to claim 1, wherein the iron loss when the excitation magnetic flux density is 1 T and the frequency of the alternating magnetic field is 1000 Hz is 120 W / kg or less. The feature is a dust core.

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