JP4646768B2 - Soft magnetic material, dust core, and method for producing soft magnetic material - Google Patents

Description

  The present invention relates to a soft magnetic material, a dust core, and a method of manufacturing a soft magnetic material, and more specifically, a soft magnetic material, a dust core, and a method of manufacturing a soft magnetic material that can reduce iron loss. About.

  In general, an electromagnetic steel plate is used as a soft magnetic component in an electric device having a solenoid valve, a motor, or a power supply circuit. A soft magnetic component is required to have a magnetic property that can obtain a large magnetic flux density by applying a small magnetic field and can respond sensitively to changes in the magnetic field from the outside.

  When this soft magnetic component is used in an alternating magnetic field, energy loss called iron loss occurs. This iron loss is represented by the sum of hysteresis loss and eddy current loss. Hysteresis loss corresponds to the energy required to change the magnetic flux density of the soft magnetic component. Since the hysteresis loss is proportional to the operating frequency, it becomes dominant mainly in the low frequency region of 1 kHz or less. The eddy current loss referred to here is energy loss mainly caused by eddy current flowing in the soft magnetic component. Since the eddy current loss is proportional to the square of the operating frequency, the eddy current loss becomes dominant mainly in a high frequency region of 1 kHz or more.

Soft magnetic parts are required to have magnetic characteristics that reduce the occurrence of this iron loss. To achieve this, the magnetic permeability μ of the soft magnetic part, by increasing the saturation magnetic flux density Bs and the electrical resistivity [rho, it is necessary to reduce the coercive force H _c of the soft magnetic component.

  In recent years, since the operating frequency has been increased toward higher output and higher efficiency of equipment, a dust core having a smaller eddy current loss than a magnetic steel sheet has attracted attention. The dust core 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. Metal magnetic particles are Fe, Fe-Si alloy, Fe-Al (aluminum) alloy, Fe-N (nitrogen) alloy, Fe-Ni (nickel) alloy, Fe-C (carbon) alloy, Fe -B (boron) based alloy, Fe-Co (cobalt) based alloy, Fe-P based alloy, Fe-Ni-Co based alloy, Fe-Cr (chromium) based alloy or Fe-Al-Si based alloy Has been.

  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 the distortion and dislocation in the metal magnetic particles, it is necessary to heat-treat the molded dust core at a high temperature of 400 ° C. or higher, preferably 550 ° C. or higher, more preferably 650 ° C. or higher. is there.

  However, the insulating coating is made of an amorphous compound such as an iron phosphate compound for the reason that resistance to powder deformation during molding is required, and sufficient high-temperature stability is not obtained. That is, when the dust core is to be heat-treated at a high temperature of 400 ° C. or higher, the insulating property is lost due to the diffusion of metal elements constituting the metal magnetic particles into the amorphous state. For this reason, when trying to reduce the hysteresis loss by high-temperature heat treatment, there has been a problem that the electrical resistivity ρ of the dust core 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 higher 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, techniques that can improve the high-temperature stability of the insulating coating are disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-272911 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2003-303711 (Patent Document 2). Patent Document 1 discloses a soft magnetic material made of composite magnetic particles having an aluminum phosphate-based insulating coating with high temperature stability. 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.

Patent Document 2 discloses an iron-based powder in which the surface of a powder containing iron as a main component is coated with a coating containing a silicone resin and a pigment, and is used as a lower layer of the coating containing a silicone resin and a pigment. An iron-based powder having a coating containing a phosphorus compound is disclosed.
JP 2003-272911 A JP 2003-303711 A

  However, the technique disclosed in Patent Document 1 has a drawback that the adhesion between the aluminum phosphate and the metal magnetic particles is insufficient, and the flexibility of the aluminum phosphate insulating coating is low. For this reason, when the iron powder on which the aluminum phosphate insulating coating is formed is pressure-molded, the insulating coating is damaged by pressure, and the electrical resistivity ρ of the soft magnetic material is reduced. As a result, there is a problem that eddy current loss increases. In the technique disclosed in Patent Document 2, both heat resistance and flexibility cannot be improved, and the iron loss cannot be sufficiently reduced.

  Accordingly, an object of the present invention is to provide a soft magnetic material, a powder magnetic core, and a method for producing a soft magnetic material that can reduce iron loss.

The soft magnetic material of the present invention is a soft magnetic material including composite magnetic particles having metal magnetic particles mainly composed of Fe (iron) and an insulating film covering the metal magnetic particles, wherein the insulating film is phosphoric acid. And Fe and one or more atoms selected from the group consisting of Al, Si (silicon), Ti (titanium), and Zr (zirconium) . The atomic ratio of Fe contained in the contact surface of the insulating coating that comes into contact with the metal magnetic particles is larger than the atomic ratio of Fe contained in the surface of the insulating coating. The atomic ratio of the one or more atoms included in the contact surface of the insulating coating that contacts the metal magnetic particles is smaller than the atomic ratio of the one or more atoms included in the surface of the insulating coating.

According to the soft magnetic material of the present invention, the contact surface of the insulating coating that contacts the metal magnetic particles is formed of a layer containing a large amount of phosphoric acid and Fe. Since the layer containing a large amount of phosphoric acid and Fe has high adhesion to Fe, the adhesion between the metal magnetic particles and the insulating coating can be improved. Therefore, the insulating coating is less likely to be damaged during pressure molding, and an increase in eddy current loss can be suppressed. The surface of the insulating coating is formed of a layer containing a large amount of phosphoric acid and one or more atoms selected from the group consisting of Al, Si, Ti, and Zr . A layer containing a large amount of phosphoric acid and one or more atoms selected from the group consisting of Al, Si, Ti, and Zr has higher temperature stability than a layer containing a large amount of phosphoric acid and Fe. Even if the magnetic material is heat-treated at high temperature, it does not break. Also, it plays a role of preventing the decomposition of the layer formed on the contact surface of the insulating coating that contacts the metal magnetic particles. Therefore, the heat resistance of the insulating coating can be improved, and the hysteresis loss of the dust core obtained by press-molding this soft magnetic material can be reduced without deteriorating the eddy current loss. As described above, the iron loss of the dust core can be reduced.

Te soft magnetic material odor of the present invention, the insulating film includes a first insulating coating covering the metal magnetic particles, and a second insulating film covering the first insulating coating. The first insulating coating consists phosphate and Fe, a second insulating coating contains said one or more atoms with phosphoric acid.

  As a result, the insulating coating includes a first insulating coating that has good adhesion to the metal magnetic particles, and a second insulating coating that has higher temperature stability than the first insulating coating and covers the first insulating coating. It becomes a two-layer structure. The first insulating coating can improve the adhesion between the magnetic metal particles and the insulating coating, and the second insulating coating can improve the heat resistance of the insulating coating.

  In the soft magnetic material of the present invention, preferably, the composite magnetic particles further have a coating film containing Si that exhibits insulating properties to cover the surface of the insulating coating film. Thereby, since insulation between metal magnetic particles is ensured by the coating film containing Si, an increase in eddy current loss of the powder magnetic core obtained by press-forming this soft magnetic material can be further suppressed.

The dust core of the present invention is produced by pressure-molding the soft magnetic material.
A method for producing a soft magnetic material according to one aspect of the present invention is a method for producing a soft magnetic material including composite magnetic particles having metal magnetic particles mainly composed of Fe and an insulating film covering the metal magnetic particles. And a step of forming an insulating film covering the metal magnetic particles. The step of forming the insulating coating includes a first coating step of forming a first insulating coating by coating a metal magnetic particle with a compound or solution containing Fe ions and phosphate ions, and after the first coating step, The first insulating film is coated with a compound or solution containing one or more ions selected from the group consisting of Al ions, Si ions, Mn ions, Ti ions, Zr ions, and Zn ions and phosphate ions. Thus, a second covering step of forming a second insulating film is included.

A method for producing a soft magnetic material according to another aspect of the present invention is a method for producing a soft magnetic material including composite magnetic particles having metal magnetic particles mainly composed of Fe and an insulating film covering the metal magnetic particles. And a step of forming the insulating coating for coating the metal magnetic particles. The step of forming the insulating coating includes a first coating step of forming a first insulating coating by adding a phosphoric acid solution to a suspension in which soft magnetic particle powder is dispersed in an organic solvent, and mixing and stirring. after one coating step, a phosphoric acid, Al, Si, Ti, and Z r than made solution of a metal alkoxide containing one or more atoms selected from the group added to the suspension in, by mixing and stirring And a second covering step for forming a second insulating film.

  According to the method for producing a soft magnetic material of the present invention, the contact surface of the insulating coating that contacts the metal magnetic particles is formed of the first insulating coating containing phosphoric acid and Fe. Since the layer containing a large amount of phosphoric acid and Fe has high adhesion to Fe, the adhesion between the metal magnetic particles and the insulating coating can be improved. Accordingly, the insulating coating is less likely to be damaged during pressure molding, and an increase in eddy current loss of the powder magnetic core obtained by pressure molding this soft magnetic material can be suppressed. The surface of the insulating coating is formed of a second insulating coating containing phosphoric acid and one or more atoms selected from the group consisting of Al, Si, Ti, and Zr. The layer containing a large amount of phosphoric acid and one or more atoms selected from the group consisting of Al, Si, Ti, and Zr has high-temperature stability as compared with the first insulating film containing phosphoric acid and Fe. Therefore, the insulating property does not deteriorate even if the soft magnetic material is heat-treated at a high temperature. The second insulating film also serves to prevent decomposition of the first insulating film. Therefore, the heat resistance of the insulating coating can be improved, and the hysteresis loss of the dust core obtained by press-molding this soft magnetic material can be reduced. As described above, the iron loss of the dust core can be reduced.

  In the present specification, “having Fe as a main component” means that the proportion of Fe is 50% by mass or more.

  According to the soft magnetic material, the powder magnetic core, and the method for producing the soft magnetic material of the present invention, the insulating coating is less likely to be damaged during pressure molding, and an increase in eddy current loss of the powder magnetic core can be suppressed. . In addition, the heat resistance of the insulating coating can be improved, and the hysteresis loss can be reduced. Therefore, the iron loss of the dust core can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is an enlarged schematic view showing a dust core produced using the soft magnetic material according to Embodiment 1 of the present invention. As shown in FIG. 1, the dust core produced using the soft magnetic material in the present embodiment includes a plurality of composites having metal magnetic particles 10 and insulating coatings 20 that cover the surfaces of the metal magnetic particles 10. Magnetic particles 30 are included. Each of the plurality of composite magnetic particles 30 is bonded by, for example, an organic substance (not shown) or the engagement of the unevenness of the composite magnetic particle 30.

  The metal magnetic particles 10 are, for example, Fe, Fe—Si based alloy, Fe—Al based alloy, Fe—N (nitrogen) based alloy, Fe—Ni (nickel) based alloy, Fe—C (carbon) based alloy, Fe— B (boron) based alloy, Fe—Co (cobalt) based alloy, Fe—P based alloy, Fe—Ni—Co based alloy, Fe—Cr (chromium) based alloy, Fe—Al—Si based alloy, etc. ing. The metal magnetic particles 10 need only contain Fe as a main component, and may be a single metal or an alloy.

  The average particle diameter of the metal magnetic particles 10 is preferably 5 μm or more and 300 μm or less. When the average particle diameter of the metal magnetic particles 10 is 5 μm or more, the metal is not easily oxidized, so that it is possible to suppress a decrease in the magnetic characteristics of the soft magnetic material. Moreover, when the average particle diameter of the metal magnetic particle 10 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 diameter is a 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 insulating coating 20 has an insulating coating 20a made of, for example, an iron phosphate compound, and an insulating coating 20b made of, for example, an aluminum phosphate compound. The metal magnetic particles 10 are covered with an insulating coating 20a, and the insulating coating 20a is covered with an insulating coating 20b. That is, the metal magnetic particles 10 are covered with the insulating film 20 having a two-layer structure. The insulating coating 20 functions as an insulating layer between the metal magnetic particles 10. By covering the metal magnetic particles 10 with the insulating coating 20, it is possible to increase the electrical resistivity ρ of the dust core obtained by pressure-molding this soft magnetic material. Thereby, it can suppress that an eddy current flows between the metal magnetic particles 10, and can reduce the eddy current loss of a powder magnetic core. In the present embodiment, the case where the insulating coating 20b is made of an aluminum phosphate compound has been described. However, in the present invention, in addition to such a case, the insulating coating 20b is made of a manganese phosphate compound or a zinc phosphate compound. It may be.

  The thickness of the insulating coating 20 is preferably 0.005 μm or more and 20 μm or less. By setting the thickness of the insulating coating 20 to 0.005 μm or more, energy loss due to eddy current can be effectively suppressed. Further, by setting the thickness of the insulating coating 20 to 20 μm or less, the proportion of the insulating coating 20 in the soft magnetic material does not become too large. For this reason, it can prevent that the magnetic flux density of the powder magnetic core obtained by pressure-molding this soft magnetic material falls remarkably.

  FIG. 2A is an enlarged view showing one composite magnetic particle in FIG. FIG. 2B is a diagram showing changes in the atomic ratio of Fe and the atomic ratio of Al along the line II-II in the insulating film of FIG.

  Referring to FIGS. 2A and 2B, the insulating coating 20a contains a certain amount of Fe and does not contain Al. The atomic ratio of Fe and the atomic ratio of Al change discontinuously at the boundary surface between the insulating coating 20a and the insulating coating 20b. The insulating coating 20b does not contain Fe, and a certain amount of Al is present. include. That is, the atomic ratio of Fe contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is larger than the atomic ratio of Fe contained in the surface of the insulating coating 20. Further, the atomic ratio of Al contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is smaller than the atomic ratio of Al contained in the surface of the insulating coating 20.

Then, the method to manufacture the powder magnetic core shown in FIG. 1 is demonstrated.
FIG. 3 is a diagram showing a method of manufacturing a dust core according to Embodiment 1 of the present invention in the order of steps. Referring to FIG. 3, metal magnetic particles 10 which are mainly composed of Fe and are made of, for example, pure iron, Fe, Fe—Si alloy, or Fe—Co alloy are prepared. Heat treatment is performed at 400 ° C. or higher and lower than 900 ° C. (step S1). The heat treatment temperature is more preferably 700 ° C. or higher and lower than 900 ° C. Numerous strains (dislocations and defects) exist inside the metal magnetic particles 10 before the heat treatment. This distortion can be reduced by performing heat treatment on the metal magnetic particles 10. This heat treatment may be omitted.

Next, the insulating coating 20a is formed by, for example, a wet processing method (step S2). This process will be described in detail. First, an aqueous solution is applied to the metal magnetic particles 10 by immersing the metal magnetic particles 10 in the aqueous solution. As an aqueous solution used in the present embodiment, an aqueous solution (first solution) containing Fe ions and PO ₄ (phosphate) ions is used. The pH of the aqueous solution is adjusted using, for example, NaOH. The immersion time of the metal magnetic particles 10 is, for example, 10 minutes. During the immersion, the aqueous solution is continuously stirred so that the metal magnetic particles 10 do not settle on the bottom. By applying an aqueous solution to the metal magnetic particles 10, the metal magnetic particles 10 are covered with an insulating coating 20a made of an iron phosphate compound. Thereafter, the metal magnetic particles 10 coated with the insulating coating 20a are washed with water and acetone.

  Next, the metal magnetic particles 10 coated with the insulating coating 20a are dried (step S3). Drying is performed at a temperature of 150 ° C. or lower, preferably at a temperature of 100 ° C. or lower. Moreover, drying is performed for 120 minutes, for example.

Next, an insulating coating 20b made of an aluminum phosphate compound is formed by, for example, a wet processing method (step S4). Specifically, the aqueous solution (second solution) is applied to the insulating coating 20a by immersing the metal magnetic particles 10 with the insulating coating 20a formed in the aqueous solution. As the aqueous solution used in this embodiment, an aqueous solution containing Al ions and PO ₄ ions is used. The detailed conditions other than this are substantially the same as the conditions for forming the insulating coating 20a, and the description thereof is omitted.

Further, in the present embodiment, the case where the insulating coating 20b made of an aluminum phosphate compound is formed is shown, but an aqueous solution containing Mn ions and PO ₄ ions instead of an aqueous solution containing Al ions and PO ₄ ions. May be used to form the insulating coating 20b made of a manganese phosphate compound. Alternatively, the insulating coating 20b made of a zinc phosphate compound may be formed using an aqueous solution containing Zn ions and PO ₄ ions.

  Next, the metal magnetic particles 10 coated with the insulating coating 20b are dried (step S5). Drying is performed at a temperature of 150 ° C. or lower, preferably at a temperature of 100 ° C. or lower. Moreover, drying is performed for 120 minutes, for example.

  Through the above steps, the soft magnetic material of the present embodiment is completed. In addition, when producing a powder magnetic core, the following processes are further performed.

  Next, the obtained powder of the soft magnetic material is put into a mold, and pressure-molded with a pressure of, for example, 390 (MPa) to 1500 (MPa) (step S6). Thereby, the compacting body in which the powder of the metal magnetic particle 10 was compressed is obtained. Note that the pressure forming atmosphere 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.

  Next, the green compact obtained by pressure molding is heat-treated at a temperature of 400 ° C. or higher and 900 ° C. or lower (step S7). Since many distortions and dislocations are generated in the green compact after the pressure forming step, such distortions and dislocations can be removed by heat treatment. The dust core shown in FIG. 1 is completed by the steps described above.

  The soft magnetic material of the present embodiment is a soft magnetic material including composite magnetic particles 30 having metal magnetic particles 10 containing Fe as a main component and an insulating film 20 covering the metal magnetic particles 10. 20 contains an iron phosphate compound and an aluminum phosphate compound. The atomic ratio of Fe contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is larger than the atomic ratio of Fe contained in the surface of the insulating coating 20. The atomic ratio of Al contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is smaller than the atomic ratio of Al contained in the surface of the insulating coating 20.

  According to the soft magnetic material of the present embodiment, the contact surface of the insulating coating 20 that contacts the metal magnetic particles 10 is formed of an iron phosphate compound. The adhesion between Fe and the iron phosphate compound includes the adhesion between Fe and the aluminum phosphate compound, the adhesion between Fe and the silicic acid compound, the adhesion between Fe and the manganese phosphate compound, Since the adhesion with the zinc phosphate compound is superior, the adhesion between the metal magnetic particles 10 and the insulating coating 20 can be improved. Therefore, the insulating coating 20 is less likely to be damaged during pressure molding, and an increase in eddy current loss of the powder magnetic core obtained by pressure molding this soft magnetic material can be suppressed. Further, the surface of the insulating coating 20 is formed of an aluminum phosphate compound. Since the aluminum phosphate compound has higher temperature stability than the iron phosphate compound, even if the soft magnetic material is heat-treated at a high temperature, the insulating coating 20b does not deteriorate the insulating property. It also plays a role of preventing the insulating coating 20a from being decomposed. Therefore, the heat resistance of the insulating coating 20 can be improved, and the hysteresis loss of the powder magnetic core obtained by pressure molding this soft magnetic material can be reduced. As described above, the iron loss of the dust core can be reduced.

  In the soft magnetic material of the present embodiment, the insulating coating 20 has an insulating coating 20a that covers the metal magnetic particles 10 and an insulating coating 20b that covers the insulating coating 20a. The insulating coating 20a is made of an iron phosphate compound, and the insulating coating 20b is made of an aluminum phosphate compound.

  As a result, the insulating coating 20 has two properties: an insulating coating 20a that has good adhesion to the metal magnetic particles 10, and an insulating coating 20b that has better high temperature stability than the insulating coating 20a and covers the insulating coating 20a. It becomes a layer structure. The insulating coating 20a can improve the adhesion between the metal magnetic particles 10 and the insulating coating 20, and the insulating coating 20b can improve the heat resistance of the insulating coating 20.

  The method of manufacturing a soft magnetic material according to the present embodiment is a method of manufacturing a soft magnetic material including composite magnetic particles 30 having metal magnetic particles 10 containing Fe as a main component and an insulating coating 20 covering the metal magnetic particles 10. And the process of forming the insulating film 20 which coat | covers the metal magnetic particle 10 is provided. The step of forming the insulating coating 20 includes the following steps. By coating the metal magnetic particles 10 with a compound or solution containing Fe ions and phosphate ions, the insulating coating 20a is formed. After forming the insulating coating 20a, the insulating coating 20b is formed by coating the insulating coating 20a with a compound or solution containing Al ions and phosphate ions.

  According to the method for manufacturing a soft magnetic material of the present embodiment, the contact surface of the insulating coating 20 that contacts the metal magnetic particles 10 is formed of the insulating coating 20a containing an iron phosphate compound. Since Fe and the iron phosphate compound have high adhesion, the adhesion between the metal magnetic particles 10 and the insulating coating 20 can be improved. Therefore, the insulating coating 20 is less likely to be damaged during pressure molding, and an increase in eddy current loss of the powder magnetic core obtained by pressure molding this soft magnetic material can be suppressed. Further, the surface of the insulating coating 20 is formed of an insulating coating 20b containing an aluminum phosphate compound. Since the aluminum phosphate compound has better high-temperature stability than the insulating coating 20a containing the iron phosphate compound, the insulation deterioration is caused even if the powder magnetic core obtained by pressure-molding this soft magnetic material is heat-treated at a high temperature. Is small. The insulating film 20b also serves to prevent the insulating film 20a from being decomposed. Therefore, the heat resistance of the insulating coating 20 can be improved, and the hysteresis loss of the dust core can be reduced. As described above, the iron loss of the dust core can be reduced.

  In the first embodiment, the case where the insulating coating 20 is formed by the wet coating process is shown. However, the present invention is not limited to such a case, and instead of the wet coating process, the insulating coating 20 is formed. The insulating coating 20 may be formed by a mechanical alloying method in which the solid powdery compound of the component and the metal magnetic particles 10 are mechanically mixed to form a film, a sputtering method, or the like.

  In the present embodiment, the case where the insulating coating 20a is made of an iron phosphate compound and the insulating coating 20b is made of an aluminum phosphate compound has been shown, but the present invention is limited to such a case. Instead, the insulating coating 20a contains phosphoric acid and Fe, and the insulating coating 20b contains phosphoric acid and one or more atoms selected from the group consisting of Al, Si, Mn, Ti, Zr, and Zn. It only has to be included.

(Embodiment 2)
FIG. 4 is an enlarged schematic view showing a dust core produced using the soft magnetic material according to Embodiment 2 of the present invention. As shown in FIG. 4, the dust core produced using the soft magnetic material in the present embodiment includes a plurality of composites having metal magnetic particles 10 and insulating coatings 20 that cover the surfaces of the metal magnetic particles 10. Magnetic particles 30 are included. The insulating coating 20 has an insulating coating 20a made of an iron phosphate compound, an insulating coating 20b made of an iron phosphate compound and an aluminum phosphate compound, and an insulating coating 20c made of an aluminum phosphate compound. The metal magnetic particles 10 are covered with an insulating coating 20a, the insulating coating 20a is covered with an insulating coating 20b, and the insulating coating 20b is covered with an insulating coating 20c. That is, the metal magnetic particles 10 are covered with the insulating film 20 having a three-layer structure.

  FIG. 5A is an enlarged view showing one composite magnetic particle in FIG. FIG. 5B is a diagram showing changes in the atomic ratio of Fe and the atomic ratio of Al along the VV line in the insulating film of FIG.

  5A and 5B, the insulating coating 20a contains a certain amount of Fe and does not contain Al. The atomic ratio of Fe and the atomic ratio of Al change discontinuously at the boundary surface between the insulating coating 20a and the insulating coating 20b, and the insulating coating 20b contains Fe in a smaller amount than the insulating coating 20a. A certain amount of Al is also included. Then, the atomic ratio of Fe and the atomic ratio of Al change discontinuously at the boundary surface between the insulating coating 20b and the insulating coating 20c. The insulating coating 20c does not contain Fe, and Al is insulated. It is contained in a larger amount than the coating 20b. The atomic ratio of Fe contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is larger than the atomic ratio of Fe contained in the surface of the insulating coating 20. Further, the atomic ratio of Al contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is smaller than the atomic ratio of Al contained in the surface of the insulating coating 20.

Then, the method to manufacture the powder magnetic core shown in FIG. 4 is demonstrated.
FIG. 6 is a diagram showing a method of manufacturing a dust core according to Embodiment 2 of the present invention in the order of steps. Referring to FIG. 6, in the manufacturing method of the present embodiment, the aqueous solution used in forming insulating coating 20b is different from that of the first embodiment. Further, after the insulating coating 20b is dried (step S5), the insulating coating 20c is formed (step S5a), and the insulating coating 20c is dried (step S5b), which is different from the first embodiment.

Specifically, an insulating film 20b (Step S4) When, instead of the aqueous solution containing Al ions and PO ₄ ions, an aqueous solution containing the Fe ions and Al ions and PO ₄ ions. The concentration of Fe ions contained in this aqueous solution is smaller than the concentration of Fe ions contained in the aqueous solution used when forming the insulating coating 20a. By using such an aqueous solution, it is possible to form the insulating coating 20b made of an iron phosphate compound and an aluminum phosphate compound and containing Fe in a smaller amount than the insulating coating 20a.

Next, the metal magnetic particles 10 coated with the insulating coating 20b are dried (step S5). Subsequently, an insulating film 20c made of an aluminum phosphate compound is formed by, for example, a bond method (step S5a). Specifically, the aqueous solution is applied to the insulating coating 20b by immersing the metal magnetic particles 10 with the insulating coating 20b formed in the aqueous solution. As the aqueous solution used in this embodiment, an aqueous solution containing Al ions and PO ₄ ions is used. Thereafter, the metal magnetic particles 10 coated with the insulating coating 20c are dried (step S5b).

  Since the structure of the dust core and the manufacturing method thereof other than the above are substantially the same as the structure of the dust core and the manufacturing method shown in the first embodiment, description thereof is omitted.

  As in the present embodiment, even if the insulating coating 20 is composed of three layers of insulating coatings 20a to 20c, the atomic ratio of Fe contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is that of the insulating coating. As long as it is larger than the atomic ratio of Fe contained in the surface and the atomic ratio of aluminum contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is smaller than the atomic ratio of aluminum contained in the surface of the insulating coating 20, The effects of the present invention can be obtained.

(Embodiment 3)
In the dust core using the soft magnetic material in the present embodiment, the atomic ratio of Fe and Al contained in the insulating coatings 20a to 20c is different from that in the second embodiment. That is, the insulating coating 20 has an insulating coating 20a made of an iron phosphate compound and an aluminum phosphate compound, an insulating coating 20b made of an iron phosphate compound, and an insulating coating 20c made of an aluminum phosphate compound.

  FIG. 7 is a diagram showing changes in the atomic ratio of Fe and the atomic ratio of Al along the line VV in FIG. 5A in the insulating coating according to the third embodiment of the present invention. Referring to FIG. 7, the insulating coating 20a contains a certain amount of Fe and Al. The atomic ratio of Fe and the atomic ratio of Al change discontinuously at the boundary surface between the insulating coating 20a and the insulating coating 20b, and the insulating coating 20b contains Fe in a larger amount than the insulating coating 20a. Al is not included. Then, the atomic ratio of Fe and the atomic ratio of Al change discontinuously at the boundary surface between the insulating coating 20b and the insulating coating 20c. The insulating coating 20c does not contain Fe, and Al is insulated. It is contained in a larger amount than the coating 20a. The atomic ratio of Fe contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is larger than the atomic ratio of Fe contained in the surface of the insulating coating 20. Further, the atomic ratio of Al contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is smaller than the atomic ratio of Al contained in the surface of the insulating coating 20.

The manufacturing method of the soft magnetic material in the present embodiment is different from that in the second embodiment in the aqueous solution used in forming the insulating coatings 20a and 20b. Specifically, an insulating film 20a (step S2) when, in place of the aqueous solution containing Fe ions and PO ₄ ions, an aqueous solution containing the Fe ions and Al ions and PO ₄ ions. The concentration of Al ions contained in this aqueous solution is smaller than the concentration of Al ions contained in the aqueous solution used when forming the insulating coating 20c. By using such an aqueous solution, it is possible to form an insulating coating 20a made of an iron phosphate compound and an aluminum phosphate compound. When forming the insulating coating 20b (step S4), an aqueous solution containing Fe ions and PO ₄ ions is used instead of an aqueous solution containing Fe ions, Al ions, and PO ₄ ions. By using such an aqueous solution, the insulating coating 20b made of an iron phosphate compound can be formed.

  The other structure and manufacturing method of the dust core are substantially the same as the structure and manufacturing method of the dust core shown in the second embodiment, and a description thereof will be omitted.

  As in the present embodiment, the insulating coating 20 is composed of three insulating coatings 20a to 20c, and the atomic ratio of Fe contained in the insulating coating 20b is greater than the atomic ratio of Fe contained in the insulating coating 20a. In many cases, even if the atomic ratio of Al contained in the insulating coating 20b is smaller than the atomic ratio of Al contained in the insulating coating 20a, Fe atoms contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 The atomic ratio of aluminum contained in the surface of the insulating coating 20 is larger than the atomic ratio of Fe contained in the surface of the insulating coating, and the atomic ratio of aluminum contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 The effect of the present invention can be obtained as long as it is smaller.

(Embodiment 4)
FIG. 8 is an enlarged schematic view showing a dust core produced using the soft magnetic material according to Embodiment 4 of the present invention. As shown in FIG. 8, the dust core produced using the soft magnetic material in the present embodiment includes a plurality of composites having metal magnetic particles 10 and insulating coatings 20 covering the surfaces of the metal magnetic particles 10. Magnetic particles 30 are included. The insulating film 20 is a single insulating film made of an iron phosphate compound and an aluminum phosphate compound.

  FIG. 9A is an enlarged view showing one composite magnetic particle in FIG. FIG. 9B is a diagram showing changes in the atomic ratio of Fe and the atomic ratio of Al along the line IX-IX in the insulating film of FIG.

  Referring to FIGS. 9A and 9B, the atomic ratio of Fe monotonously decreases from the contact surface in contact with metal magnetic particle 10 toward the surface of insulating coating 20. The atomic ratio of Al monotonously increases from the contact surface in contact with the metal magnetic particles 10 toward the surface of the insulating coating 20. That is, the atomic ratio of Fe contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is larger than the atomic ratio of Fe contained in the surface of the insulating coating 20. Further, the atomic ratio of Al contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is smaller than the atomic ratio of Al contained in the surface of the insulating coating 20.

Next, a method for manufacturing the dust core shown in FIG. 8 from a soft magnetic material will be described.
FIG. 10 is a diagram illustrating a method of manufacturing a dust core according to Embodiment 4 of the present invention in the order of steps. Referring to FIG. 10, the manufacturing method of the present embodiment is different from that of the first embodiment in that insulating coatings 20a and 20b are heat-treated (step S5c) after insulating coating 20b is dried (step S5).

  Specifically, after the metal magnetic particles 10 coated with the insulating coating 20b are dried (step S5), the insulating coatings 20a and 20b are heat-treated at a temperature of, for example, 250 ° C. for 5 hours (step S5c). As a result, Fe atoms in the insulating coating 20a diffuse into the insulating coating 20b, and Al atoms in the insulating coating 20b diffuse into the insulating coating 20a. As a result, the boundary between the insulating coating 20a and the insulating coating 20b disappears and a single insulating coating 20 is formed.

  Since the structure of the dust core and the manufacturing method thereof other than the above are substantially the same as the structure of the dust core and the manufacturing method shown in the first embodiment, description thereof is omitted.

  As in the present embodiment, even if the insulating coating 20 is composed of a single layer of the insulating coating 20, the atomic ratio of Fe contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is that of the insulating coating. As long as it is larger than the atomic ratio of Fe contained in the surface and the atomic ratio of aluminum contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is smaller than the atomic ratio of aluminum contained in the surface of the insulating coating 20, The effects of the present invention can be obtained.

(Embodiment 5)
FIG. 11 is an enlarged schematic view showing a dust core produced using the soft magnetic material according to Embodiment 5 of the present invention. As shown in FIG. 11, the dust core made of the soft magnetic material according to the present embodiment includes a metal magnetic particle 10, an insulating film 20 that covers the surface of the metal magnetic particle 10, and an insulating film 20. A plurality of composite magnetic particles 30 having a coating 25 made of a silicone resin to be coated are included.

Then, the method to manufacture the powder magnetic core shown in FIG. 11 is demonstrated.
FIG. 12 is a diagram illustrating a method of manufacturing a dust core according to the fifth embodiment of the present invention in the order of steps. Referring to FIG. 12, the manufacturing method of the present embodiment is different from that of Embodiment 1 in that after insulating coating 20b is dried (step S5), film 25 made of silicone resin is formed (step S5d). Yes.

  Specifically, after the metal magnetic particles 10 coated with the insulating coating 20b are dried (step S5), the metal magnetic particles 10 coated with the insulating coating 20b and the paint containing a silicone resin and a pigment are mixed. . Alternatively, a paint containing a silicone resin and a pigment is sprayed on the metal magnetic particles 10 coated with the insulating coating 20b. Thereafter, the paint is dried and the solvent is removed. Thereby, the coating film 25 made of a silicone resin is formed.

  Since the structure of the dust core and the manufacturing method thereof other than the above are substantially the same as the structure of the dust core and the manufacturing method shown in the first embodiment, description thereof is omitted.

  In the soft magnetic material of the present embodiment, the composite magnetic particle 30 further has a coating 25 made of a silicone resin that covers the surface of the insulating coating 20. Thereby, since insulation between the metal magnetic particles 10 is ensured by the coating film 25, an increase in eddy current loss of the powder magnetic core obtained by pressure-molding this soft magnetic material can be further suppressed.

  In the present embodiment, the case where the film 25 made of a silicone resin is formed has been described, but the present invention is not limited to such a case, and a film containing Si may be formed. .

In the first to fifth embodiments, the insulating coating 20 includes an aluminum phosphate compound, but instead of the insulating coating 20 including an aluminum phosphate compound, a manganese phosphate compound, The effect of the present invention can be obtained even if a zinc phosphate compound is included. The insulating coating 20 containing these compounds is an aqueous solution containing Si ions and PO ₄ ions, an aqueous solution containing Mn ions and PO ₄ ions, Ti ions, instead of an aqueous solution containing Al ions and PO ₄ ions. and and aqueous solution containing PO ₄ ion, and an aqueous solution containing a Zr ions and PO ₄ ions can be formed by using an aqueous solution containing Zn ions and PO ₄ ions.

(Embodiment 6)
FIG. 13 (a) is an enlarged view showing one composite magnetic particle in the sixth embodiment of the present invention. FIG. 13B is a diagram showing changes in the atomic ratio of Fe and the atomic ratio of Al along the line XIII-XIII in the insulating film of FIG. Referring to FIG. 13, in the dust core using the soft magnetic material in the present embodiment, the atomic ratio of Fe and Al contained in insulating coatings 20a and 20b is different from that in the first embodiment. That is, the insulating coating 20 has an insulating coating 20a formed by the reaction of iron and phosphoric acid present on the surface of the metal magnetic particles 10, and an insulating coating 20b made of phosphoric acid and an aluminum compound.

  The insulating coating 20a contains a certain amount of Fe and does not contain Al. In the boundary region 20d between the insulating coating 20a and the insulating coating 20b, the atomic ratio of Fe decreases and the atomic ratio of Al increases. The insulating coating 20b contains Fe in a smaller amount than the insulating coating 20a, and also contains a certain amount of Al. The atomic ratio of Fe contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is larger than the atomic ratio of Fe contained in the surface of the insulating coating 20. Further, the atomic ratio of Al contained in the contact surface of the insulating coating 20 in contact with the metal magnetic particles 10 is smaller than the atomic ratio of Al contained in the surface of the insulating coating 20.

Then, the method to manufacture the powder magnetic core shown in FIG. 13 is demonstrated.
FIG. 14 is a diagram illustrating a method of manufacturing a dust core according to the sixth embodiment of the present invention in the order of steps. Referring to FIG. 14, the manufacturing method of the present embodiment is different from that of the first embodiment in the method of forming insulating film 20 and the subsequent processing.

In the present embodiment, after heat-treating the metal magnetic particles 10 (step S1), a phosphoric acid solution is added to a suspension in which the metal magnetic particles 10 are dispersed in an organic solvent, and mixed and stirred. Thereby, iron and phosphoric acid which exist on the surface of the metal magnetic powder 10 react, and the insulating coating 20a is formed on the surface of the metal magnetic particle 10 (step S12). Subsequently, a solution of at least one metal alkoxide containing phosphoric acid and atoms selected from the group consisting of Al, Si, Ti, and Zr is added to the suspension used in forming the insulating coating 20a. Mix and stir. At this time, the metal alkoxide reacts with water and is hydrolyzed to produce a metal oxide or a metal hydrated oxide. Thereby, the insulating coating 20b which consists of phosphoric acid and a metal compound is formed in the surface of the metal magnetic particle 10 (step S13). And the metal magnetic particle 10 coat | covered with the insulating film 20 is dried (step S14). Specifically, after drying in a draft at room temperature for 3 to 24 hours, drying is performed in a temperature range of 60 to 120 ° C., or drying is performed in a temperature range of 30 to 80 ° C. in a reduced pressure atmosphere. In addition, it can be dried either in air or in an inert gas atmosphere such as N ₂ gas, but from the viewpoint of preventing oxidation of metal magnetic particles, it can be dried in an inert gas atmosphere such as N ₂ gas. preferable. Thereby, the soft magnetic material of this Embodiment is obtained.

  Note that the organic solvent used in the present embodiment may be a generally used organic solvent, and a water-soluble organic solvent is preferable. Specifically, alcohol solvents such as ethyl alcohol, propyl alcohol or butyl alcohol, ketone solvents such as acetone or methyl ethyl ketone, glycol ether solvents such as methyl cellosolve, ethyl cellosolve, propyl cellosolve or butyl cellosolve, diethylene glycol, triethylene glycol , Polyethylene glycol, dipropylene glycol, or oxyethylene such as tripropylene glycol or polypropylene glycol, oxypropylene addition polymers, alkylene glycol such as ethylene glycol, propylene glycol or 1,2,6-hexanetriol, glycerin, 2-pyrrolidone Etc. In particular, alcohol solvents such as ethyl alcohol, propyl alcohol, and butyl alcohol, and ketone solvents such as acetone and methyl ethyl ketone are preferable.

  The phosphoric acid used in this embodiment may be an acid formed by hydration of diphosphorus pentoxide. Specific examples include metaphosphoric acid, pyrophosphoric acid, orthophosphoric acid, triphosphoric acid, and tetraphosphoric acid. Orthophosphoric acid is particularly preferable.

  The metal alkoxide used in the present embodiment is an alkoxide containing an atom selected from the group consisting of Al, Si, Ti, and Zr. As the alkoxide, methoxide, ethoxide, propoxide, isopropoxide, oxyisopropoxide, butoxide and the like can be used. As the alkoxide, ethyl silicate or methyl silicate obtained by partially hydrolyzing and condensing tetraethoxysilane or tetramethoxysilane can be used. Considering the uniformity of treatment and treatment effect, tetraethoxysilane, tetramethoxysilane, methyl silicate, aluminum triisopropoxide, aluminum tributoxide, zirconium tetraisopropoxide, titanium tetraisopropoxide, etc. are used as alkoxides. It is particularly preferred.

  As an apparatus for mixing the metal magnetic particle powder with the phosphoric acid solution and the metal alkoxide solution, for example, a high-speed agitate type mixer is used. Specifically, a Henschel mixer, a speed mixer, a ball cutter, a power mixer, a hybrid mixer, A corn blender or the like is used.

The mixing / stirring of the metal magnetic particle powder with the phosphoric acid solution and the metal alkoxide solution is preferably performed at a temperature of room temperature or higher and lower than the boiling point of the organic solvent used. From the viewpoint of oxidation prevention of metal magnetic particles, it is preferred to conduct the reaction under an inert gas atmosphere such as N ₂ gas.

  The other methods of manufacturing the powder magnetic core are substantially the same as the structure of the powder magnetic core shown in the first embodiment and the method of manufacturing the same, and thus the description thereof is omitted.

  According to the soft magnetic material of the present embodiment, the same effect as in the first embodiment can be obtained.

  Examples of the present invention will be described below. In this example, the effects of reducing iron loss and improving heat resistance in a powder magnetic core obtained by press molding the soft magnetic material of the present invention were investigated. First, samples 1 to 6 which are soft magnetic materials were produced by the following method.

  Sample 1 (Invention Example): Prepared according to the manufacturing method of Embodiment 1. Specifically, by preparing ABC100.30 manufactured by Höganäs AB, whose iron purity is 99.8% or more, as metal magnetic particles 10 and immersing it in an aqueous iron phosphate solution, The insulating coating 20a to be formed was formed on the surface of the metal magnetic particle 10 with an average thickness of 50 nm. Next, by dipping in an aluminum phosphate aqueous solution, an insulating coating 20b made of an aluminum phosphate compound was formed on the surface of the insulating coating 20a with an average thickness of 50 nm, and a soft magnetic material serving as Sample 1 was obtained.

  Sample 2 (Invention Example): Prepared according to the manufacturing method of Embodiment 5. Specifically, a soft magnetic material obtained by a method similar to the manufacturing method of Sample 1 was prepared, and this soft magnetic material was immersed in a solution in which a silicone resin was dissolved and dispersed in ethyl alcohol. As a result, a film 25 made of a silicone resin having an average thickness of 100 nm was formed on the surface of the insulating film 20, and a soft magnetic material to be the sample 2 was obtained.

  Sample 3 (Comparative Example): Only an insulating film made of an iron phosphate compound was formed. Specifically, ABC100.30 manufactured by Höganäs AB was prepared as metal magnetic particles, and this was immersed in an iron phosphate aqueous solution to form an insulating coating made of an iron phosphate compound with an average thickness of 100 nm. A soft magnetic material to be sample 3 was obtained.

  Sample 4 (Comparative Example): Only an insulating film made of an aluminum phosphate compound was formed. Specifically, ABC100.30 manufactured by Höganäs AB was prepared as metal magnetic particles, and this was immersed in an aluminum phosphate aqueous solution to form an insulating coating made of an aluminum phosphate compound with an average thickness of 100 nm. A soft magnetic material that was formed on the surface of No. 10 and became Sample 4 was obtained.

Sample 5 (Invention Example): An aqueous solution of phosphoric acid (phosphoric acid content: 85% by weight) in a suspension obtained by suspending ABC100.30 manufactured by Höganäs AB, whose purity of iron is 99.8% or more, in acetone. Was added dropwise and stirred and mixed at a reaction temperature of 45 ° C. for 20 minutes under a N ₂ stream. Next, an acetone solution in which aluminum isopropoxide was dispersed was added to the mixed solution, and then tetraethoxysilane was added, followed by stirring and mixing for 20 minutes. The obtained mixed solution was dried under reduced pressure at 45 ° C., and a soft magnetic material to be sample 5 was obtained.

  Sample 6 (Invention): An insulating coating made of silicone was formed on the surface of the insulating coating of Sample 5. Specifically, a film made of a silicone resin having an average thickness of 100 nm was formed on the surface of the insulating film of Sample 5, and a soft magnetic material to be Sample 6 was obtained.

  Next, with respect to the produced samples 1 to 6, using the “X-ray photoelectron analyzer ESCA3500” (Shimadzu Corporation), measurement of the abundance ratio of each atom in the depth direction while performing etching by high-speed Ar ion etching Was done. Moreover, it cut | disconnected by FIB (Focused Ion Beam) and the composition analysis was performed about the cross section of the insulating coating 20 using EDX (Energy-Dispersive X-ray diffraction). For the composition evaluation, the peak area of the Kα spectrum of each element of P, Fe, and Al was measured, the ratio of the Fe peak area to the P peak area, and the ratio of the Al peak area to the P peak area (the presence of Fe / P atoms). Ratio, Al / P atom abundance ratio) was used as an index.

The heat resistance of the soft magnetic material was determined by the following method. First, 0.5 g of sample powder was weighed and subjected to pressure molding at a pressure of 13.72 MPa using a KBr tablet molding machine (Shimadzu Corporation) to prepare a cylindrical sample to be measured. Then, the temperature 25 ° C. The sample to be measured, after exposure for 12 hours or more under a relative humidity of 60% environment, sets this measured sample between stainless steel electrodes, the electric resistance measuring apparatus (model 4329A lateral Hokushin electric The resistance value R (mΩ) was measured by applying a voltage of 15V.

Next, the area A (cm ² ) and the thickness t0 (cm) of the upper surface of the sample to be measured (cylindrical) are measured, and each measured value is inserted into the following equation 1 to determine the volume resistivity (mΩ · cm). Asked.

Volume resistivity (mΩ · cm) = R × (A / t0) (1)
The sample to be measured is put into an electric furnace, the temperature of the electric furnace is changed variously, heat treatment is performed at each temperature for 1 hour, the volume resistivity value before and after heating at each temperature is measured, and the following formula 2 is heated. Insert the volume resistivity values before and after to determine the rate of change in volume resistivity, plot the heating temperature on the horizontal axis and the rate of change in volume resistivity on the vertical axis using a semilogarithmic graph, The temperature at which the rate of change in resistance value was exactly 10% was defined as the heat resistant temperature of the soft magnetic material.

Change rate of volume resistivity value before and after heating (%) = {volume resistivity value (before heating) −volume resistivity value (after heating)} / volume resistivity value (before heating) × 100 (2)
Subsequently, Samples 1 to 6 were pressure-molded at a pressure of 1275 MPa to produce a ring-shaped dust core. Next, heat treatment was performed at a temperature of 550 ° C. for 1 hour in a nitrogen atmosphere. And the frequency was changed about the samples 1-6, and the eddy current loss coefficient b was evaluated by measuring the iron loss in excitation magnetic flux density 1.0 (T). Table 1 shows the average thickness of the iron phosphate compound, the average thickness of the aluminum phosphate compound, the average thickness of the silicone resin, and the eddy current loss coefficient b for Samples 1 to 6. The eddy current loss coefficient b is the iron loss W W = a × f + b × f ² (f: frequency, a, b: constant)
Is a constant b.

As shown in Table 1, with respect to the eddy current loss coefficient b, the eddy current loss coefficient b of the sample 1 is 0.025 (× 10 ⁻³ W · s ² / kg), and the eddy current loss coefficient b of the sample 2 is It was 0.021 (× 10 ⁻³ W · s ² / kg). On the other hand, the eddy current loss coefficient b of the sample 3 is 0.022 (× 10 ⁻³ W · s ² / kg), and the eddy current loss coefficient b of the sample 4 is 0.048 (× 10 ⁻³ W · s ^2). / Kg). The eddy current loss coefficient b of the sample 5 is 0.024 (× 10 ⁻³ W · s ² / kg), and the eddy current loss coefficient b of the sample 6 is 0.016 (× 10 ⁻³ W · s ² / kg). )Met. Further, the heat resistance of Samples 1, 2, 5, and 6 was superior to that of Sample 3, and was equivalent to that of Sample 4 .

Thus, samples 1, 2, 5, and 6 have a smaller hysteresis loss coefficient a at the heat-resistant temperature than sample 3, and exhibit an eddy current loss coefficient b equivalent to that of sample 3. It can be seen that 2, 5, and 6 have a lower iron loss than Sample 3. Samples 1, 2, 5, and 6 are similar to Sample 4 in that the value of hysteresis loss coefficient a at the heat-resistant temperature is close to that of Sample 4, and the value of eddy current loss coefficient b is smaller than that of Sample 4. 5 and 6 show that the iron loss is smaller than that of the sample 4. That is, it can be seen that iron loss can be reduced by forming the insulating coating 20a made of an iron phosphate compound and the insulating coating 20b made of an aluminum phosphate compound. Moreover, since the heat resistance of each of the samples 2 and 6 is higher than that of each of the samples 1 and 5, the hysteresis loss can be further reduced by forming the film 25 made of silicone resin. I understand. Further, since the eddy current loss coefficient b of each of the samples 2 and 6 is smaller than the eddy current loss coefficient b of each of the samples 1 and 5, the eddy current is formed by forming the coating 25 made of silicone resin. It can be seen that the loss is further reduced. From the above, it can be seen that the iron loss can be further reduced by forming the coating 25 made of silicone resin.

  Regarding Samples 5 and 6, the average particle diameter is 100 μm, and the thickness of the insulating coating is 50 nm for the insulating coating 20a, which is the first insulating coating, and 50 nm for the insulating coating 20b, which is the second insulating coating. there were. The Fe / P atom abundance ratio at the contact surface between the metal magnetic particle 10 and the insulating coating 20 evaluated using an X-ray photoelectron analyzer is 12.9 or 13.6, and the presence of Fe / P atoms on the surface of the insulating coating. The ratio was 3.3 or 3.0. Therefore, the Fe / P atom abundance ratio at the contact surface between the metal magnetic particles 10 and the insulating coating 20 is larger than the Fe / P atom abundance ratio at the surface of the insulating coating. The Al / P atom abundance ratio at the contact surface between the metal magnetic particle 10 and the insulating coating 20 is 0.7 or 0.8, and the Al / P atom abundance ratio at the surface of the insulating coating is 2.2 or 2 Therefore, the Al / P atom abundance ratio at the contact surface between the metal magnetic particles 10 and the insulating coating 20 is smaller than the Al / P atom abundance ratio at the surface of the insulating coating.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is the schematic diagram which expanded and showed the powder magnetic core produced using the soft-magnetic material in Embodiment 1 of this invention. (A) is an enlarged view showing one composite magnetic particle in FIG. (B) is a figure which shows the change of the atomic ratio of Fe and the atomic ratio of Al along the II-II line in the insulating film of (a). It is a figure which shows the manufacturing method of the powder magnetic core in Embodiment 1 of this invention in order of a process. It is the schematic diagram which expanded and showed the powder magnetic core produced using the soft-magnetic material in Embodiment 2 of this invention. (A) is an enlarged view showing one composite magnetic particle in FIG. (B) is a figure which shows the change of the atomic ratio of Fe and the atomic ratio of Al along the VV line in the insulating film of (a). It is a figure which shows the manufacturing method of the powder magnetic core in Embodiment 2 of this invention in order of a process. It is a figure which shows the change of the atomic ratio of Fe and the atomic ratio of Al along the VV line | wire of Fig.5 (a) in the insulating film of Embodiment 3 of this invention. It is the schematic diagram which expanded and showed the powder magnetic core produced using the soft-magnetic material in Embodiment 4 of this invention. (A) is an enlarged view showing one composite magnetic particle in FIG. (B) is a figure which shows the change of the atomic ratio of Fe and the atomic ratio of Al along the IX-IX line in the insulating film of (a). It is a figure which shows the manufacturing method of the powder magnetic core in Embodiment 4 of this invention in order of a process. It is the schematic diagram which expanded and showed the powder magnetic core produced using the soft-magnetic material in Embodiment 5 of this invention. It is a figure which shows the manufacturing method of the powder magnetic core in Embodiment 5 of this invention in order of a process. (A) It is an enlarged view which shows one composite magnetic particle in Embodiment 6 of this invention. (B) It is a figure which shows the change of the atomic ratio of Fe and the atomic ratio of Al along the XIII-XIII line in the insulating film of (a). It is a figure which shows the manufacturing method of the powder magnetic core in Embodiment 6 of this invention in order of a process.

Explanation of symbols

  10 metal magnetic particles, 20, 20a to 20c insulating coating, 20d boundary region, 25 coating, 30 composite magnetic particles.

Claims (5)

A soft magnetic material including composite magnetic particles having metal magnetic particles containing Fe as a main component and an insulating film covering the metal magnetic particles,
The insulating coating includes phosphoric acid, Fe , and one or more atoms selected from the group consisting of Al, Si, Ti, and Zr ,
The atomic ratio of Fe contained in the contact surface of the insulating coating in contact with the metal magnetic particles is larger than the atomic ratio of Fe contained in the surface of the insulating coating,
The atomic ratio of the one or more atoms contained in the contact surface of the insulating coating in contact with metal magnetic particles, rather smaller than the atomic ratio of the one or more atoms contained in the surface of the insulating coating,
The insulating coating has a first insulating coating that covers the metal magnetic particles, and a second insulating coating that covers the first insulating coating,
The first insulating coating is made of phosphoric acid and Fe, and the second insulating coating is a soft magnetic material containing phosphoric acid and the one or more atoms . The soft magnetic material according to claim 1 , wherein the composite magnetic particle further has a coating film containing Si that covers a surface of the insulating coating film. A dust core produced by pressure-molding the soft magnetic material according to claim 1 . A method for producing a soft magnetic material comprising composite magnetic particles having metal magnetic particles containing Fe as a main component and an insulating film covering the metal magnetic particles,
Comprising the step of forming the insulating coating covering the metal magnetic particles,
The step of forming the insulating film includes
A first coating step of forming a first insulating film by coating the metal magnetic particles with a compound or solution containing Fe ions and phosphate ions;
After the first coating step, a compound or solution containing one or more ions selected from the group consisting of Al ions, Si ions, Mn ions, Ti ions, Zr ions, and Zn ions, and phosphate ions is added to the first coating step. A method for producing a soft magnetic material, comprising: a second coating step of forming a second insulating coating by coating the first insulating coating. A method for producing a soft magnetic material comprising composite magnetic particles having metal magnetic particles containing Fe as a main component and an insulating film covering the metal magnetic particles,
Comprising the step of forming the insulating coating covering the metal magnetic particles,
The step of forming the insulating film includes
A first coating step of forming a first insulating film by adding a phosphoric acid solution to a suspension in which soft magnetic particle powder is dispersed in an organic solvent, and mixing and stirring;
After the first coating step, a solution of phosphoric acid and a metal alkoxide containing one or more atoms selected from the group consisting of Al, Si, Ti, and Zr is added to the suspension and mixed and stirred. Thus, the manufacturing method of a soft-magnetic material including the 2nd coating process which forms a 2nd insulating film.

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