WO2013100143A1 - Composite soft magnetic material and production method therefor - Google Patents

Composite soft magnetic material and production method therefor Download PDF

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Publication number
WO2013100143A1
WO2013100143A1 PCT/JP2012/084158 JP2012084158W WO2013100143A1 WO 2013100143 A1 WO2013100143 A1 WO 2013100143A1 JP 2012084158 W JP2012084158 W JP 2012084158W WO 2013100143 A1 WO2013100143 A1 WO 2013100143A1
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powder
soft magnetic
silicone resin
inorganic insulating
magnetic powder
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PCT/JP2012/084158
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French (fr)
Japanese (ja)
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小林　直樹
宮原　正久
克彦 森
裕明 池田
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株式会社ダイヤメット
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Priority to CN201280059179.7A priority Critical patent/CN103959405A/en
Publication of WO2013100143A1 publication Critical patent/WO2013100143A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
    • H01F1/20—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/22—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H01F1/24—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated
    • H01F1/26—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated by macromolecular organic substances
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B22F1/102—Metallic powder coated with organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/16—Metallic particles coated with a non-metal
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
    • H01F1/20—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/22—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H01F1/24—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/33—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials mixtures of metallic and non-metallic particles; metallic particles having oxide skin

Definitions

  • the present invention relates to a composite soft magnetic material having good direct current superposition characteristics while maintaining a high specific resistance, and a method for producing the same.
  • Laminated steel cores, ferrite cores, and dust cores have long been used as iron cores for reactors.
  • the manufacturing cost is increased due to the reduction of the thickness.
  • the ferrite core and the dust core have a low saturation magnetic flux density, which causes a decrease in inductance in a large current application, and there is a problem of increasing the size in order to avoid it.
  • a soft magnetic material previously coated with an insulating film may be used in order to further improve the insulation between the soft magnetic powder particles.
  • the silicone resin when the silicone resin is hard, a sufficient gap is formed between the soft magnetic powder particles, so that a good DC superposition characteristic can be obtained, but the silicone resin breaks during molding and covers the soft magnetic material.
  • the insulating film As a result, defects are given to the insulating film to be reduced, the specific resistance is lowered, the soft magnetic characteristics are deteriorated, and the loss is increased.
  • a soft silicone resin when a soft silicone resin is used, good soft magnetic properties can be obtained due to high specific resistance, but it is difficult to maintain a uniform gap between soft magnetic powder particles during molding. There was a problem that would get worse.
  • the composite soft magnetic material according to claim 1 of the present invention is formed by uniformly mixing a coating powder obtained by coating a soft magnetic powder coated with an insulating coating with a silicone resin and an inorganic insulating powder, and molding the mixture.
  • the thickness of the thick segregated portion of the insulating layer made of the silicone resin and the inorganic insulating powder is one in the cross-sectional observation.
  • the average segregation thickness D ( ⁇ m) obtained by measuring two places on the soft magnetic powder particles and measuring the average of 20 or more particles is 5 times or less of X.
  • the composite soft magnetic material according to claim 2 of the present invention is the composite soft magnetic material according to claim 1, wherein the soft magnetic powder is pure iron powder having an average particle size of 10 to 100 ⁇ m, and the inorganic insulating powder has an average particle size of 1 ⁇ m or less.
  • the total amount of the silicone resin and the inorganic insulating powder is 0.3 to 2% by mass with respect to the soft magnetic powder.
  • the composite soft magnetic material according to claim 3 of the present invention is the composite soft magnetic material according to claim 2, wherein the amount of the silicone resin in the total amount of the silicone resin and the inorganic insulating powder is 0.15 to 1 with respect to the soft magnetic powder. .2 mass%, and the amount of the inorganic insulating powder is 0.1 to 1 mass% with respect to the soft magnetic powder.
  • the composite soft magnetic material according to claim 4 of the present invention is characterized in that in any one of claims 1 to 3, the insulating coating is an iron phosphate film or a magnesium oxide film.
  • a method for producing a composite soft magnetic material comprising: coating a soft magnetic powder coated with an insulating film with a silicone resin to obtain a coated powder; and then uniformly coating the coated powder and the inorganic insulating powder. It mixes, the mixture is shape
  • the outer side of the silicone resin coated with the soft magnetic powder is obtained by uniformly mixing the coated powder obtained by coating the soft magnetic powder coated with the insulating film with the silicone resin and the inorganic insulating powder. Since the inorganic insulating powder adheres uniformly without agglomeration and the thickness of the insulating layer after molding is made uniform without segregation, the gap between the soft magnetic powder particles is kept constant, which is high.
  • a composite soft magnetic material having specific resistance and good DC superposition characteristics is provided. Moreover, since the composite soft magnetic material of the present invention has a high specific resistance value and can suppress eddy current loss, it can also be used in a large reactor.
  • the inorganic insulating powder is dispersed between the soft magnetic powder grains so that the gap between the soft magnetic powder particles is reduced during molding.
  • a composite soft magnetic material that can be held uniformly and has good direct current superposition characteristics is provided.
  • the composite soft magnetic material of the present invention is obtained by uniformly mixing a coating powder obtained by coating a soft magnetic powder coated with an insulating coating with a silicone resin and an inorganic insulating powder, and molding and firing the mixture. It is obtained. Also, the method for producing a composite soft magnetic material of the present invention comprises uniformly mixing a coating powder obtained by coating a soft magnetic powder coated with an insulating coating with a silicone resin and an inorganic insulating powder, and molding the mixture. , Which is fired.
  • a soft magnetic powder is obtained by uniformly mixing a coating powder obtained by coating a soft magnetic powder coated with an insulating coating with a silicone resin and an inorganic insulating powder.
  • the inorganic insulating powder 3 adheres to the outside of the silicone resin 2 coated with 1.
  • Reference numeral 4 denotes an insulating coating for covering the soft magnetic powder 1.
  • FIG. 4 shows a schematic diagram of a coating powder obtained by mixing an inorganic insulating powder in a process different from the present invention.
  • FIG. 4 (a) is a coating powder mixed with an inorganic insulating powder according to the present invention.
  • the soft magnetic powder and the inorganic insulating powder are first mixed to obtain the soft magnetic powder to which the inorganic insulating powder is adhered, and the coated powder coated with the silicone resin is shown in FIG. 4B.
  • the inorganic insulating powder adheres to the outside of the soft magnetic powder, and the outside is covered with a silicone resin.
  • an inorganic insulating powder and a silicone resin are mixed to obtain a silicone resin in which the inorganic insulating powder is dispersed, and the coated powder obtained by mixing this with a soft magnetic powder is coated as shown in FIG. A mixture of silicone resin and inorganic insulating powder is coated on the outside of the soft magnetic powder.
  • the inorganic insulating powder dispersed in the silicone resin is aggregated in the drying process of the silicone resin, and thus is not uniformly coated as shown in FIG. Due to this aggregation, the inorganic insulating powder and the silicone resin do not reach the surface of the soft magnetic powder sufficiently, the coating film thickness becomes uneven, the film becomes partially thin, the specific resistance decreases, and the gap between the soft magnetic powder particles is reduced. The DC superimposition characteristic is deteriorated without being sufficiently maintained.
  • the soft magnetic powder used in the present invention is preferably pure iron powder having an average particle size of 10 to 100 ⁇ m.
  • pure iron powder having an average particle size of 10 to 100 ⁇ m as the soft magnetic powder, a composite soft magnetic material can be produced in a normal production facility, and a composite soft magnetic material having good DC superposition characteristics is obtained. It becomes possible.
  • the average particle size of the inorganic insulating powder used in the present invention is preferably 1 ⁇ m or less. If it exceeds 1 ⁇ m, the gap between the soft magnetic powder particles becomes large and the inductance becomes too low.
  • the total amount of the silicone resin and the inorganic insulating powder is preferably 0.3 to 2% by mass with respect to the soft magnetic powder. If it is less than 0.3% by mass, the direct current superimposition characteristics in the high current region deteriorate, which is not preferable. On the other hand, if it exceeds 2% by mass, the density of the composite soft magnetic material obtained by deterioration of compressibility is lowered, and as a result, a high magnetic flux density cannot be obtained, which is not preferable.
  • the amount of the silicone resin is preferably 0.15 to 1.2% by mass with respect to the soft magnetic powder. If it is less than 0.15% by mass, the film thickness becomes thin, insulation cannot be maintained, and the specific resistance decreases, which is not preferable. On the other hand, if it exceeds 1.2% by mass, the density of the composite soft magnetic material obtained by the deterioration of compressibility is lowered, and a high magnetic flux density cannot be obtained.
  • the amount of the inorganic insulating powder in the total amount is preferably 0.1 to 1.0% by mass with respect to the soft magnetic powder. If it is less than 0.1% by mass, the inorganic insulating powder does not spread over the entire surface of the soft magnetic powder, and the gap between the soft magnetic powder particles cannot be maintained, and the direct current superposition characteristics are deteriorated. On the other hand, if it exceeds 1.0% by mass, the density of the composite soft magnetic material obtained due to the deterioration of compressibility is reduced, and not only a high magnetic flux density cannot be obtained, but also a large amount of fine particles existing between the soft magnetic powder particles. Such inorganic insulating powder is not preferable because the moldability is lowered and the strength of the molded body is lowered.
  • the insulating film covering the soft magnetic powder is preferably an iron phosphate film or a magnesium oxide film. This is because soft magnetic powder such as pure iron powder coated with an iron phosphate film or a magnesium oxide film is easily available and inexpensive.
  • the firing is preferably performed at 500 ° C. or higher.
  • the firing temperature is set to 500 ° C. or higher, distortion after molding can be largely removed.
  • a silicone resin a methyl silicone resin and a methylphenyl silicone resin can be used, for example.
  • the inorganic insulating powder for example, silicon dioxide (silica, SiO 2 ), aluminum oxide (alumina, Al 2 O 3 ), magnesium oxide (magnesia, MgO) can be used.
  • the thickness of the insulating layer made of the silicone resin and the inorganic insulating powder between the soft magnetic powder particles is uniform.
  • the state can be discriminated by the average segregation thickness D obtained by measuring the thickness of the thickly segregated portion at two locations for one soft magnetic powder particle, measuring 20 or more particles, and calculating the average value in cross-sectional observation.
  • the average segregation thickness D between the soft magnetic powder particles is small. In an ideal state, the thickness is the same as that of the insulating layer.
  • the silicone resin and the inorganic insulating powder are concentrated locally such as triple points.
  • the segregation part becomes thick and the average segregation thickness D increases, and the soft magnetic powder particles Since the silicone resin and inorganic insulating powder of the insulating layer are deprived by the segregated portion, the thickness of the insulating layer is reduced.
  • the average segregation thickness D increases and decreases with the total amount X mass% added of the silicone resin and the inorganic insulating powder, but it can be said that the average segregation thickness D is approximately uniform when it is 5 times or less of X.
  • the segregation part of the insulating layer becomes thicker, while the insulating layer between the soft magnetic powder particles becomes too thin, so that the insulation becomes incomplete and the specific resistance decreases. Or, the gap between the soft magnetic powder particles is not sufficiently formed, and the direct current superimposition characteristic is deteriorated.
  • the average segregation thickness D ( ⁇ m) is 5 times or less, more preferably 4 times or less of the total amount X mass% of the silicone resin and the inorganic insulating powder.
  • the soft magnetic powder water atomized pure iron powder (S110i, manufactured by Höganäs Japan Co., Ltd.) subjected to a phosphate coating treatment with an average particle size of about 50 ⁇ m was used.
  • the silicone resin methylphenyl type (KR resin manufactured by Shin-Etsu Chemical Co., Ltd.) was used.
  • the inorganic insulating powder hydrophobic silica powder (R974 manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 170 to 180 m 2 / g and an average particle diameter of about 12 nm was used.
  • the soft magnetic powder and 0.7% by mass (however, the amount of solute excluding the solvent) of the soft magnetic powder are uniformly mixed and stirred at 50 ° C. with stirring at 50 ° C. Drying for 5 hours was performed to obtain a coated powder obtained by coating a soft magnetic powder with a silicone resin.
  • the coating powder and an inorganic insulating powder of 0.5% by mass with respect to the soft magnetic powder were uniformly mixed.
  • the inorganic insulating powder 3 adheres to the outside of the silicone resin 2 coated with the soft magnetic powder 1.
  • 0.8% by mass of a wax-based lubricant for powder metallurgy is added to the soft magnetic powder, and the mixture is molded at a molding pressure of 8 t / cm 2 and then fired in a nitrogen atmosphere at 620 ° C. for 30 minutes. (Example A).
  • this coating powder is uniformly mixed with 1.0% by mass of an inorganic insulating powder with respect to the soft magnetic powder, and further 0.8% by mass of a wax-based lubricant for powder metallurgy with respect to the soft magnetic powder.
  • the mixture was added and the mixture was molded at a molding pressure of 8 t / cm 2 and then fired in a nitrogen atmosphere at 620 ° C. for 30 minutes (Example B). Further, as a comparative example, firing was performed in the same manner as above except that the inorganic insulating powder was not mixed (Comparative Example a).
  • the DC superposition characteristics were evaluated by measuring the inductance of AC 10 kHz in a DC magnetic field of m. The result is shown in FIG. In both Examples A and B, the rate of decrease in inductance was lower than that in Comparative Example a even in a wide magnetic field range, and it was confirmed that the examples had good DC superposition characteristics.
  • the influence of the timing of mixing the inorganic insulating powder on the density, specific resistance, and magnetic permeability of the sample was examined.
  • the raw materials were the same as in Example 1 and the same as in Example 1 unless conditions were specified.
  • Example C First, a soft magnetic powder and 0.7% by mass of a silicone resin with respect to the soft magnetic powder are uniformly mixed and dried while stirring to obtain a coated powder in which the soft magnetic powder is coated with the silicone resin. It was.
  • this coating powder and an inorganic insulating powder of 0.5% by mass with respect to the soft magnetic powder were uniformly mixed.
  • the inorganic insulating powder adheres to the outside of the silicone resin coated with the soft magnetic powder.
  • lubricant 0.8% by mass is added to the soft magnetic powder, and the mixture is molded at a molding pressure of 8 t / cm 2 or 12 t / cm 2 and then fired in a nitrogen atmosphere at 620 ° C. for 30 minutes. Went.
  • each 60 ⁇ 10 ⁇ 5 mm bar-shaped sample was prepared, and the specific resistance value was measured by a four-terminal method.
  • the soft magnetic powder to which the inorganic insulating powder was adhered and 0.7% by mass of the silicone resin with respect to the soft magnetic powder were uniformly mixed and dried while stirring, so that the inorganic insulating powder was adhered.
  • a coated powder obtained by coating a soft magnetic powder with a silicone resin was obtained.
  • the powder at this time has an inorganic insulating powder attached to the outside of the soft magnetic powder, and the outside is covered with a silicone resin.
  • lubricant 0.8% by mass is added to the soft magnetic powder, and the mixture is molded at a molding pressure of 8 t / cm 2 or 12 t / cm 2 and then fired in a nitrogen atmosphere at 620 ° C. for 30 minutes. Went.
  • each 60 ⁇ 10 ⁇ 5 mm bar-shaped sample was prepared, and the specific resistance value was measured by a four-terminal method.
  • Comparative example c Soft magnetic powder, 0.7% by mass of silicone resin with respect to soft magnetic powder, and 0.5% by mass of inorganic insulating powder with respect to soft magnetic powder are uniformly mixed and dried with stirring. Thus, a coating powder obtained by coating the soft magnetic powder with a mixture of silicone resin and inorganic insulating powder was obtained. As shown in FIG. 4C, the powder at this time is coated with a mixture of a silicone resin and an inorganic insulating powder on the outside of the soft magnetic powder.
  • a lubricant is added to the soft magnetic powder, and the mixture is molded at a molding pressure of 8 t / cm 2 or 12 t / cm 2 and then fired in a nitrogen atmosphere at 620 ° C. for 30 minutes. Went.
  • each 60 ⁇ 10 ⁇ 5 mm bar-shaped sample was prepared, and the specific resistance value was measured by a four-terminal method.
  • Example C it was confirmed that the rate of decrease in inductance was lower than that in Comparative Examples b and c in a wide magnetic field range, and had good DC superposition characteristics. Regarding the density, no significant difference was observed between Example C and Comparative Examples b and c. The specific resistance was significantly higher in Example C than in Comparative Examples b and c, and the maximum specific permeability was significantly lower in Example C than in Comparative Examples b and c. In Example C, the specific resistance and the maximum relative permeability did not change with the molding pressure.
  • a composite powder obtained by coating a soft magnetic powder with a silicone resin and an inorganic insulating powder are uniformly mixed, and the mixture is molded and fired. It was confirmed that a magnetic material was obtained.
  • Example 9A is a photograph of Example C
  • FIG. 9B is a photograph of Comparative Example b.
  • this inorganic insulating powder is partially aggregated and segregated, the inorganic insulating powder and the silicone resin are not sufficiently distributed between the soft magnetic powder particles, so that the thickness of the insulating layer becomes uneven, Therefore, it is considered that the specific resistance is lowered, the specific resistance is lowered, or the gap between the soft magnetic powder particles is not sufficiently maintained, and the direct current superimposition characteristic is deteriorated.
  • FIG. 9A according to Example C of the present invention has few defective portions due to aggregation of the inorganic insulating powder, and in the present invention, the inorganic insulating powder and the silicone resin are sufficiently distributed between the soft magnetic powder particles. As a result, the thickness of the insulating layer becomes uniform, a high specific resistance can be maintained, and a sufficient gap between the soft magnetic powder particles can be maintained, so that it is considered that good direct current superposition characteristics are obtained.
  • the average segregation thickness was measured.
  • the thickness of the thick part of the segregation of the insulating layer made of the silicone resin and the inorganic insulating powder is measured at two locations for one soft magnetic powder particle as shown in FIG. Measurement was performed and an average value was calculated. That is, in the insulating layer made of silicone resin and inorganic insulating powder, the size of the largest gap among the gaps formed between any soft magnetic powder particles adjacent to one soft magnetic powder particle, and 2 The size of the second largest gap was measured, 20 particles were measured, and the average value was calculated. The results are shown in Table 1.
  • Example C The average segregation thickness of Example C was 3.8 ⁇ m, which was smaller than the average segregation thickness of Comparative Example b of 7.8 ⁇ m. From this, it was confirmed that Example C had little segregation of the insulating layer between the soft magnetic powder particles, and therefore the thickness of the insulating layer was uniform.
  • the size of the largest gap among the gaps formed between any soft magnetic powder particles adjacent to one soft magnetic powder particle, and 2 The size of the second largest gap was measured, and this was measured for 20 particles to determine the average segregation thickness D ( ⁇ m). Further, the ratio of the average segregation thickness D to the total amount X mass% of the silicone resin and the inorganic insulating powder, D / X, was obtained. The results are shown in the table.
  • the composite soft magnetic material was produced under the same conditions as in Example 1 except for the conditions shown in the following table.
  • the characteristic values were compared in terms of specific resistance, inductance L in a high magnetic field region (10 kA / m), and direct current superposition characteristics in terms of the rate of decrease in inductance L from 0 to 5.3 kA / m.
  • the soft magnetic material a material coated with an iron phosphate film or a magnesium oxide (MgO) film was used.
  • Silicone resins include methylphenyl soft (hardness 3.9 MHv) (A in the table), methyl soft (hardness 5.0 MHv) (B in the table), methyl alkyl hard ( The one having a hardness of 8.9 MHv (C in the table) was used.
  • silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), and magnesium oxide (MgO) were used.
  • the average particle diameter of the soft magnetic powder is 10 to 100 ⁇ m, the average particle diameter of the inorganic insulating powder is 1 ⁇ m or less, and the total amount (addition total amount) of the silicone resin and the inorganic insulating powder is 0. 3 to 2% by mass, the amount of the silicone resin is 0.15 to 1.2% by mass with respect to the soft magnetic powder, and the amount of the inorganic insulating powder is 0.1 to 1% by mass with respect to the soft magnetic powder.
  • the inorganic insulating powder is added after the soft magnetic powder is coated with the silicone resin and firing is performed at 500 ° C. or higher (Examples C to R), good characteristic values are obtained. It was.
  • the ratio D / X of the average segregation thickness D of the composite soft magnetic materials (Examples C to R) exhibiting good characteristics to the total amount of added X mass% was 5 or less in all cases.
  • a specific resistance value of 2 ⁇ m is required when a reactor having a magnetic path cross section of 1 side of 50 mm and (vortex loss between grains) / (total vortex loss) is set to 5%. In the above cases, it was determined to be good.
  • the inductance (L) was determined to be good when the value in the high magnetic field region (10 kA / m) was improved by 10% or more than the commercially available dust core.
  • the inductance reduction rate (L reduction rate)

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Abstract

Provided are a composite soft magnetic material, having favorable DC bias characteristics and high specific resistance, and a production method therefor. An inorganic insulative powder (3) and a coated powder obtained by coating a soft magnetic powder (1) that is coated with an insulative film (4) with a silicone resin (2) are uniformly mixed, and the resultant mixture is molded and fired. By uniformly mixing the inorganic insulative powder (3) and the coated powder obtained by coating the soft magnetic powder that is coated with the insulative film (4) with the silicone resin (2), rupture of the insulative film due to the inorganic insulative material when molding pressed powder is prevented. By uniformly dispersing the inorganic insulative material while high specific resistance is maintained, the gap between molded soft magnetic powder particles is uniformly maintained. As a result, a composite soft magnetic material is provided having high specific resistance and favorable DC bias characteristics.

Description

複合軟磁性材料及びその製造方法Composite soft magnetic material and manufacturing method thereof
　本発明は、高い比抵抗を保ちつつ良好な直流重畳特性を有する複合軟磁性材料及びその製造方法に関する。 The present invention relates to a composite soft magnetic material having good direct current superposition characteristics while maintaining a high specific resistance, and a method for producing the same.
　リアクトルなどの鉄心として、古くから積層鋼板コアや、フェライトコア、ダストコアが用いられている。積層鋼板においては、渦電流を防止するために積層する電磁鋼板を極力薄くするする必要があった。しかし、電磁鋼板の薄板化には限界があり、また、薄板化のために製造コストが高くなってしまうという問題があった。また、フェライトコアやダストコアは、飽和磁束密度が小さく、大電流用途ではインダクタンスの低下を生じ、それを回避するために大型化を招く問題点があった。 Laminated steel cores, ferrite cores, and dust cores have long been used as iron cores for reactors. In laminated steel sheets, it was necessary to make the electromagnetic steel sheets to be laminated as thin as possible in order to prevent eddy currents. However, there is a limit to the reduction of the thickness of the electromagnetic steel sheet, and there is a problem that the manufacturing cost is increased due to the reduction of the thickness. In addition, the ferrite core and the dust core have a low saturation magnetic flux density, which causes a decrease in inductance in a large current application, and there is a problem of increasing the size in order to avoid it.
　このような背景から、積層鋼板コアや、フェライトコア、ダストコアに代わる材料として、極少量の絶縁膜を有し、高密度に圧粉成形する手法で製造される複合軟磁性材料が用いられるようになってきている。この複合軟磁性材料は、積層鋼板と比べて渦電流損失が小さく、印加磁場を大きくした際のインダクタンスの低下も小さく、高効率で良好な直流重畳特性を有する。また、フェライトコアやダストコアに比べて大電流で使用できるという利点を有する。 From such a background, composite soft magnetic materials that have a very small amount of insulating film and that are manufactured by compacting with high density are used as an alternative to laminated steel cores, ferrite cores, and dust cores. It has become to. This composite soft magnetic material has a low eddy current loss compared to the laminated steel sheet, a small decrease in inductance when the applied magnetic field is increased, and has a high efficiency and good DC superposition characteristics. Moreover, it has the advantage that it can be used with a large current compared with a ferrite core or a dust core.
　この複合軟磁性材料を製造する際には、良好な磁気特性を得るために、いかに絶縁膜を軟磁性粉末粒子間に形成するかが課題となっている。従来は、圧縮性の高い比較的軟質なシリコーン樹脂を少量添加して、軟磁性粉末粒子をシリコーン樹脂で被覆した後に、成形、焼成することで、軟磁性粉末粒子間に絶縁膜が形成された複合軟磁性材料が製造されていた。また、軟磁性粉末と無機絶縁粉末とを混合し、その混合粉末をシリコーン樹脂で被覆し、その後、成形、焼成することで、高周波数及び高磁束密度でも優れた磁気特性を有する複合軟磁性材料を製造することが開示されている（特許文献１）。 When manufacturing this composite soft magnetic material, in order to obtain good magnetic properties, how to form an insulating film between soft magnetic powder particles is a problem. Conventionally, an insulating film was formed between soft magnetic powder particles by adding a small amount of a relatively soft silicone resin with high compressibility and coating the soft magnetic powder particles with a silicone resin, followed by molding and firing. Composite soft magnetic materials have been manufactured. A composite soft magnetic material having excellent magnetic properties even at high frequencies and high magnetic flux density by mixing soft magnetic powder and inorganic insulating powder, coating the mixed powder with silicone resin, and then molding and firing. Is disclosed (Patent Document 1).
　しかし、電気自動車やハイブリッド自動車などに搭載されるリアクトルなどのように大電流の昇圧が必要な場合などでは、従来の複合軟磁性材料の直流重畳特性では満足できない場合も多く、さらに直流重畳特性の優れた複合軟磁性材料が要求されている。なお、一般に直流重畳特性を向上させるためには、エアギャップを設けて調整する必要があるが、エアギャップを入れるためには、金型の形状が複雑になり、工程、部品数も増加するため、製造コストが増加してしまうという問題があった。さらに、エアギャップにおける漏れ磁束により損失が増加してしまうという問題もあった。 However, when a large current boost is required, such as a reactor mounted on an electric vehicle or a hybrid vehicle, there are many cases where the DC superposition characteristics of the conventional composite soft magnetic material cannot be satisfied. An excellent composite soft magnetic material is required. In general, in order to improve the direct current superimposition characteristics, it is necessary to adjust by providing an air gap. However, in order to add an air gap, the shape of the mold becomes complicated, and the number of processes and parts increases. There is a problem that the manufacturing cost increases. Further, there is a problem that the loss increases due to the leakage magnetic flux in the air gap.
　また、複合軟磁性材料を製造する際には、軟磁性粉末粒子間の絶縁性をさらに高めるために、予め絶縁被膜により被覆された軟磁性材料が使用される場合もある。この場合、シリコーン樹脂が硬質のときは、軟磁性粉末粒子間に十分なギャップが形成されるため良好な直流重畳特性が得られるが、成形時にシリコーン樹脂が破損してしまって軟磁性材料を被覆する絶縁被膜にまで欠陥を与えて比抵抗が低下して軟磁気特性が悪化し、損失が増大してしまう。一方、軟質のシリコーン樹脂を用いた場合は、高い比抵抗により良好な軟磁気特性が得られるが、成形時に軟磁性粉末粒子間のギャップを均一に保持することが難しく、その結果、直流重畳特性が悪化してしまうという問題があった。 Also, when producing a composite soft magnetic material, a soft magnetic material previously coated with an insulating film may be used in order to further improve the insulation between the soft magnetic powder particles. In this case, when the silicone resin is hard, a sufficient gap is formed between the soft magnetic powder particles, so that a good DC superposition characteristic can be obtained, but the silicone resin breaks during molding and covers the soft magnetic material. As a result, defects are given to the insulating film to be reduced, the specific resistance is lowered, the soft magnetic characteristics are deteriorated, and the loss is increased. On the other hand, when a soft silicone resin is used, good soft magnetic properties can be obtained due to high specific resistance, but it is difficult to maintain a uniform gap between soft magnetic powder particles during molding. There was a problem that would get worse.
特開２０１０－２４５４６０号公報JP 2010-245460 A
　そこで、本発明は、上記の問題を一掃し、エアギャップなしの設計を可能とすることで製造コストを増加させずに得られ、高い比抵抗と良好な直流重畳特性を有する、複合軟磁性材料及びその製造方法を提供することを目的とする。 Therefore, the present invention eliminates the above-mentioned problems and allows a design without an air gap to be obtained without increasing the manufacturing cost, and has a high specific resistance and good DC superposition characteristics, and is a composite soft magnetic material And it aims at providing the manufacturing method.
　本発明の請求項１記載の複合軟磁性材料は、絶縁被膜により被覆された軟磁性粉末をシリコーン樹脂で被覆して得た被覆粉末と、無機絶縁粉末とを均一に混合し、その混合物を成形、焼成することにより得られ、前記シリコーン樹脂と前記無機絶縁粉末の総量をＸ質量％としたとき、断面観察において、シリコーン樹脂および無機絶縁粉末からなる絶縁層の偏析の厚い部分の厚みを１つの軟磁性粉末粒子について２箇所測定し、これを２０粒子以上について測定して平均した平均偏析厚さＤ(μｍ）は、Ｘの５倍以下であることを特徴とする。 The composite soft magnetic material according to claim 1 of the present invention is formed by uniformly mixing a coating powder obtained by coating a soft magnetic powder coated with an insulating coating with a silicone resin and an inorganic insulating powder, and molding the mixture. When the total amount of the silicone resin and the inorganic insulating powder is X mass%, the thickness of the thick segregated portion of the insulating layer made of the silicone resin and the inorganic insulating powder is one in the cross-sectional observation. The average segregation thickness D (μm) obtained by measuring two places on the soft magnetic powder particles and measuring the average of 20 or more particles is 5 times or less of X.
　本発明の請求項２記載の複合軟磁性材料は、請求項１において、前記軟磁性粉末は平均粒径１０～１００μｍの純鉄粉であり、前記無機絶縁粉末の平均粒径は１μｍ以下であり、前記シリコーン樹脂と前記無機絶縁粉末の総量は前記軟磁性粉末に対して０．３～２質量％であることを特徴とする。 The composite soft magnetic material according to claim 2 of the present invention is the composite soft magnetic material according to claim 1, wherein the soft magnetic powder is pure iron powder having an average particle size of 10 to 100 μm, and the inorganic insulating powder has an average particle size of 1 μm or less. The total amount of the silicone resin and the inorganic insulating powder is 0.3 to 2% by mass with respect to the soft magnetic powder.
　本発明の請求項３記載の複合軟磁性材料は、請求項２において、前記シリコーン樹脂と前記無機絶縁粉末の総量のうち、前記シリコーン樹脂の量は前記軟磁性粉末に対して０．１５～１．２質量％、前記無機絶縁粉末の量は前記軟磁性粉末に対して０．１～１質量％であることを特徴とする。 The composite soft magnetic material according to claim 3 of the present invention is the composite soft magnetic material according to claim 2, wherein the amount of the silicone resin in the total amount of the silicone resin and the inorganic insulating powder is 0.15 to 1 with respect to the soft magnetic powder. .2 mass%, and the amount of the inorganic insulating powder is 0.1 to 1 mass% with respect to the soft magnetic powder.
　本発明の請求項４記載の複合軟磁性材料は、請求項１～３のいずれか１項において、前記絶縁被膜はリン酸鉄膜又は酸化マグネシウム膜であることを特徴とする。 The composite soft magnetic material according to claim 4 of the present invention is characterized in that in any one of claims 1 to 3, the insulating coating is an iron phosphate film or a magnesium oxide film.
　本発明の請求項５記載の複合軟磁性材料の製造方法は、絶縁被膜により被覆された軟磁性粉末をシリコーン樹脂で被覆して被覆粉末を得た後、被覆粉末と無機絶縁粉末とを均一に混合し、その混合物を成形、焼成することを特徴とする。 According to a fifth aspect of the present invention, there is provided a method for producing a composite soft magnetic material comprising: coating a soft magnetic powder coated with an insulating film with a silicone resin to obtain a coated powder; and then uniformly coating the coated powder and the inorganic insulating powder. It mixes, the mixture is shape | molded and baked.
　本発明によれば、絶縁被膜により被覆された軟磁性粉末をシリコーン樹脂で被覆して得た被覆粉末と、無機絶縁粉末とを均一に混合することにより、軟磁性粉末を被覆したシリコーン樹脂の外側に無機絶縁粉末が凝集することなく均一に付着して、成形後の絶縁層の厚さを偏析することなく均一にすることにより、軟磁性粉末粒子間のギャップが一定に保持されるため、高い比抵抗と良好な直流重畳特性を有する複合軟磁性材料が提供される。また、本発明の複合軟磁性材料は高い比抵抗値を有し渦電流損失を抑制できるので、大型のリアクトルにおいても使用可能である。また、良好な直流重畳特性を有するためエアギャップを設ける必要がなく、製造コストが増加することもない。さらに、予め絶縁被膜により被覆された軟磁性材料と、軟質のシリコーン樹脂を用いた場合においても、無機絶縁粉末を軟磁性粉末の粒間に分散させて、成形時に軟磁性粉末粒子間のギャップを均一に保持することが可能となり、良好な直流重畳特性を有する複合軟磁性材料が提供される。 According to the present invention, the outer side of the silicone resin coated with the soft magnetic powder is obtained by uniformly mixing the coated powder obtained by coating the soft magnetic powder coated with the insulating film with the silicone resin and the inorganic insulating powder. Since the inorganic insulating powder adheres uniformly without agglomeration and the thickness of the insulating layer after molding is made uniform without segregation, the gap between the soft magnetic powder particles is kept constant, which is high. A composite soft magnetic material having specific resistance and good DC superposition characteristics is provided. Moreover, since the composite soft magnetic material of the present invention has a high specific resistance value and can suppress eddy current loss, it can also be used in a large reactor. In addition, since it has good direct current superposition characteristics, it is not necessary to provide an air gap, and the manufacturing cost does not increase. Furthermore, even when a soft magnetic material previously coated with an insulating coating and a soft silicone resin are used, the inorganic insulating powder is dispersed between the soft magnetic powder grains so that the gap between the soft magnetic powder particles is reduced during molding. A composite soft magnetic material that can be held uniformly and has good direct current superposition characteristics is provided.
軟磁性粉末をシリコーン樹脂で被覆して得た被覆粉末の模式図である。It is a schematic diagram of the coating powder obtained by coating soft magnetic powder with a silicone resin. 成形後の軟磁性粉末の間に介在するシリコーン樹脂と無機絶縁粉末を示す模式図である。It is a schematic diagram which shows the silicone resin and inorganic insulating powder which interpose between the soft-magnetic powder after shaping | molding. 直流重畳特性を示すグラフである。It is a graph which shows a direct current | flow superimposition characteristic. 被覆粉末の模式図である。It is a schematic diagram of coating powder. 直流重畳特性を示すグラフである。It is a graph which shows a direct current | flow superimposition characteristic. 密度を示すグラフである。It is a graph which shows a density. 比抵抗を示すグラフである。It is a graph which shows a specific resistance. 最大比透磁率を示すグラフである。It is a graph which shows the maximum relative magnetic permeability. 断面の顕微鏡写真である。It is a microscope picture of a section. 被覆の厚さの測定部分を示す模式図である。It is a schematic diagram which shows the measurement part of the thickness of coating | cover.
　本発明の複合軟磁性材料は、絶縁被膜により被覆された軟磁性粉末をシリコーン樹脂で被覆して得た被覆粉末と、無機絶縁粉末とを均一に混合し、その混合物を成形、焼成することにより得られたものである。また、本発明の複合軟磁性材料の製造方法は、絶縁被膜により被覆された軟磁性粉末をシリコーン樹脂で被覆して得た被覆粉末と、無機絶縁粉末とを均一に混合し、その混合物を成形、焼成するものである。 The composite soft magnetic material of the present invention is obtained by uniformly mixing a coating powder obtained by coating a soft magnetic powder coated with an insulating coating with a silicone resin and an inorganic insulating powder, and molding and firing the mixture. It is obtained. Also, the method for producing a composite soft magnetic material of the present invention comprises uniformly mixing a coating powder obtained by coating a soft magnetic powder coated with an insulating coating with a silicone resin and an inorganic insulating powder, and molding the mixture. , Which is fired.
　本発明によれば、絶縁被膜により被覆された軟磁性粉末をシリコーン樹脂で被覆して得た被覆粉末と、無機絶縁粉末とを均一に混合することにより、図１に示すように、軟磁性粉末１を被覆したシリコーン樹脂２の外側に無機絶縁粉末３が付着する。なお、４は軟磁性粉末１を被覆する絶縁被膜である。このように、シリコーン樹脂で軟磁性粉末を被覆した後に無機絶縁粉末を混合することで、無機絶縁粉末の分散性が良好となる。その結果、図２に示すように、成形後にシリコーン樹脂と無機絶縁粉末が軟磁性粉末の間に介在することとなり、軟磁性粉末粒子間のギャップが一定に保持されるため、高い比抵抗値と良好な直流重畳特性を有する複合軟磁性材料が得られる。 According to the present invention, as shown in FIG. 1, a soft magnetic powder is obtained by uniformly mixing a coating powder obtained by coating a soft magnetic powder coated with an insulating coating with a silicone resin and an inorganic insulating powder. The inorganic insulating powder 3 adheres to the outside of the silicone resin 2 coated with 1. Reference numeral 4 denotes an insulating coating for covering the soft magnetic powder 1. Thus, by disperse | distributing inorganic insulating powder after coat | covering soft magnetic powder with a silicone resin, the dispersibility of inorganic insulating powder becomes favorable. As a result, as shown in FIG. 2, the silicone resin and the inorganic insulating powder are interposed between the soft magnetic powders after molding, and the gap between the soft magnetic powder particles is kept constant. A composite soft magnetic material having good direct current superposition characteristics can be obtained.
　本発明とは異なる工程で無機絶縁粉末を混合した被覆粉末の模式図を図４に示す。 FIG. 4 shows a schematic diagram of a coating powder obtained by mixing an inorganic insulating powder in a process different from the present invention.
　図４（ａ）は本発明による無機絶縁粉末を混合した被覆粉末である。 FIG. 4 (a) is a coating powder mixed with an inorganic insulating powder according to the present invention.
　これに対し、はじめに軟磁性粉末と無機絶縁粉末を混合して無機絶縁粉末が付着した軟磁性粉末を得て、これにシリコーン樹脂を混合して被覆した被覆粉末は、図４（ｂ）に示すように軟磁性粉末の外側に無機絶縁粉末が付着し、その外側にシリコーン樹脂が被覆されている。 On the other hand, the soft magnetic powder and the inorganic insulating powder are first mixed to obtain the soft magnetic powder to which the inorganic insulating powder is adhered, and the coated powder coated with the silicone resin is shown in FIG. 4B. Thus, the inorganic insulating powder adheres to the outside of the soft magnetic powder, and the outside is covered with a silicone resin.
　ただし実際には、シリコーン樹脂の混合工程において、軟磁性粉末に付着した無機絶縁粉末は軟磁性粉末の表面を離れてシリコーン樹脂中に分散してしまい、分散した無機絶縁粉末はシリコーン樹脂の乾燥工程で凝集するため、図４（ｂ）のように均一に被覆されることはない。この凝集により無機絶縁粉末およびシリコーン樹脂が軟磁性粉末表面に十分行き渡らず、被覆膜厚が不均一になり、部分的に薄くなって比抵抗が低下したり、軟磁性粉末粒子間のギャップを十分保てずに直流重畳特性が悪化することになる。 However, in practice, in the silicone resin mixing process, the inorganic insulating powder adhered to the soft magnetic powder leaves the surface of the soft magnetic powder and is dispersed in the silicone resin, and the dispersed inorganic insulating powder is the silicone resin drying process. Therefore, it is not uniformly coated as shown in FIG. Due to this aggregation, the inorganic insulating powder and the silicone resin do not reach the surface of the soft magnetic powder sufficiently, the coating film thickness becomes uneven, the film becomes partially thin, the specific resistance decreases, and the gap between the soft magnetic powder particles is reduced. The DC superimposition characteristic is deteriorated without being sufficiently maintained.
　また、はじめに無機絶縁粉末とシリコーン樹脂とを混合して無機絶縁粉末が分散したシリコーン樹脂を得て、これと軟磁性粉末を混合して被覆した被覆粉末は、図４（ｃ）に示すように軟磁性粉末の外側にシリコーン樹脂と無機絶縁粉末の混合物が被覆されている。 In addition, first, an inorganic insulating powder and a silicone resin are mixed to obtain a silicone resin in which the inorganic insulating powder is dispersed, and the coated powder obtained by mixing this with a soft magnetic powder is coated as shown in FIG. A mixture of silicone resin and inorganic insulating powder is coated on the outside of the soft magnetic powder.
　ただし実際には、シリコーン樹脂中に分散した無機絶縁粉末はシリコーン樹脂の乾燥工程で凝集するため、図４（ｃ）のように均一に被覆されることはない。この凝集により無機絶縁粉末およびシリコーン樹脂が軟磁性粉末表面に十分行き渡らず、被覆膜厚が不均一になり、部分的に薄くなって比抵抗が低下したり、軟磁性粉末粒子間のギャップを十分保てずに直流重畳特性が悪化することになる。 However, in practice, the inorganic insulating powder dispersed in the silicone resin is aggregated in the drying process of the silicone resin, and thus is not uniformly coated as shown in FIG. Due to this aggregation, the inorganic insulating powder and the silicone resin do not reach the surface of the soft magnetic powder sufficiently, the coating film thickness becomes uneven, the film becomes partially thin, the specific resistance decreases, and the gap between the soft magnetic powder particles is reduced. The DC superimposition characteristic is deteriorated without being sufficiently maintained.
　一方、図４（ａ）の本発明によれば、軟磁性粉末粒子がシリコーン樹脂により均一に被覆された後に無機絶縁粉末を混合して被覆粉末の表面に付着させるため、無機絶縁粉末粒子の凝集が起こらず、被覆膜厚が均一になって高い比抵抗を保つことができ、また軟磁性粉末粒子間のギャップを均一に保つことができるため良好な直流重畳特性を得ることができる。 On the other hand, according to the present invention shown in FIG. 4 (a), the inorganic magnetic powder particles are uniformly coated with the silicone resin, and then the inorganic insulating powder is mixed and adhered to the surface of the coated powder. Therefore, the coating film thickness becomes uniform and a high specific resistance can be maintained, and the gap between the soft magnetic powder particles can be kept uniform, so that a good DC superposition characteristic can be obtained.
　また、本発明の複合軟磁性材料は高い比抵抗値を有し渦電流損失を抑制できるので、大型のリアクトルにおいても使用可能である。また、良好な直流重畳特性を有するためエアギャップを設ける必要がなく、製造コストが増加することもない。本発明の複合軟磁性材料は、リアクトルのほか、トランス、チョークコア、ノイズフィルター、スイッチング電源、ＤＣ／ＤＣコンバータ、磁気センサコア、アクチュエータ、モータコアなどの分野で利用可能である。 Moreover, since the composite soft magnetic material of the present invention has a high specific resistance value and can suppress eddy current loss, it can also be used in a large reactor. In addition, since it has good direct current superposition characteristics, it is not necessary to provide an air gap, and the manufacturing cost does not increase. The composite soft magnetic material of the present invention can be used in fields such as transformers, choke cores, noise filters, switching power supplies, DC / DC converters, magnetic sensor cores, actuators, and motor cores in addition to reactors.
　ここで、本発明に用いられる軟磁性粉末は、平均粒径１０～１００μｍの純鉄粉であることが好ましい。軟磁性粉末として、平均粒径１０～１００μｍの純鉄粉を用いることで、通常の製造設備において複合軟磁性材料を製造することができるとともに、良好な直流重畳特性を有する複合軟磁性材料を得ることが可能となる。 Here, the soft magnetic powder used in the present invention is preferably pure iron powder having an average particle size of 10 to 100 μm. By using pure iron powder having an average particle size of 10 to 100 μm as the soft magnetic powder, a composite soft magnetic material can be produced in a normal production facility, and a composite soft magnetic material having good DC superposition characteristics is obtained. It becomes possible.
　本発明に用いられる無機絶縁粉末の平均粒径は、１μｍ以下であることが好ましい。１μｍを超えると軟磁性粉末粒子間のギャップが大きくなってインダクタンスが低くなりすぎるため好ましくない。 The average particle size of the inorganic insulating powder used in the present invention is preferably 1 μm or less. If it exceeds 1 μm, the gap between the soft magnetic powder particles becomes large and the inductance becomes too low.
　また、シリコーン樹脂と無機絶縁粉末の総量は、軟磁性粉末に対して０．３～２質量％であることが好ましい。０．３質量％未満であると、高電流域での直流重畳特性が悪化するので好ましくない。一方、２質量％を超えると、圧縮性の悪化により得られる複合軟磁性材料の密度が低下し、その結果、高い磁束密度が得られなくなるため好ましくない。 The total amount of the silicone resin and the inorganic insulating powder is preferably 0.3 to 2% by mass with respect to the soft magnetic powder. If it is less than 0.3% by mass, the direct current superimposition characteristics in the high current region deteriorate, which is not preferable. On the other hand, if it exceeds 2% by mass, the density of the composite soft magnetic material obtained by deterioration of compressibility is lowered, and as a result, a high magnetic flux density cannot be obtained, which is not preferable.
　シリコーン樹脂と無機絶縁粉末の総量のうちのシリコーン樹脂の量は、軟磁性粉末に対して０．１５～１．２質量％であることが好ましい。０．１５質量％未満であると、膜厚が薄くなり絶縁を保てなくなり、比抵抗が低下するため好ましくない。一方、１．２質量％を超えると、圧縮性の悪化により得られる複合軟磁性材料の密度が低下し、高い磁束密度が得られなくなるため好ましくない。 Of the total amount of the silicone resin and the inorganic insulating powder, the amount of the silicone resin is preferably 0.15 to 1.2% by mass with respect to the soft magnetic powder. If it is less than 0.15% by mass, the film thickness becomes thin, insulation cannot be maintained, and the specific resistance decreases, which is not preferable. On the other hand, if it exceeds 1.2% by mass, the density of the composite soft magnetic material obtained by the deterioration of compressibility is lowered, and a high magnetic flux density cannot be obtained.
　また、総量のうちの無機絶縁粉末の量は、軟磁性粉末に対して０．１～１．０質量％であることが好ましい。０．１質量％未満であると、無機絶縁粉末が軟磁性粉末の表面全体に行き渡らず、軟磁性粉末粒子間のギャップを保てなくなり、直流重畳特性が悪化するため好ましくない。一方、１．０質量％を超えると、圧縮性の悪化により得られる複合軟磁性材料の密度が低下し、高い磁束密度が得られなくなるだけでなく、軟磁性粉末粒子間に存在する多量の微細な無機絶縁粉末により成形性が低下し、成形体強度が低下するため好ましくない。 Further, the amount of the inorganic insulating powder in the total amount is preferably 0.1 to 1.0% by mass with respect to the soft magnetic powder. If it is less than 0.1% by mass, the inorganic insulating powder does not spread over the entire surface of the soft magnetic powder, and the gap between the soft magnetic powder particles cannot be maintained, and the direct current superposition characteristics are deteriorated. On the other hand, if it exceeds 1.0% by mass, the density of the composite soft magnetic material obtained due to the deterioration of compressibility is reduced, and not only a high magnetic flux density cannot be obtained, but also a large amount of fine particles existing between the soft magnetic powder particles. Such inorganic insulating powder is not preferable because the moldability is lowered and the strength of the molded body is lowered.
　また、軟磁性粉末を被覆する絶縁被膜は、リン酸鉄膜又は酸化マグネシウム膜であることが好ましい。リン酸鉄膜又は酸化マグネシウム膜で被覆された純鉄粉などの軟磁性粉末は入手が容易であって、かつ、安価であるためである。 Further, the insulating film covering the soft magnetic powder is preferably an iron phosphate film or a magnesium oxide film. This is because soft magnetic powder such as pure iron powder coated with an iron phosphate film or a magnesium oxide film is easily available and inexpensive.
　また、焼成は、５００℃以上で行うのが好ましい。焼成温度を５００℃以上とすることで、成形後の歪を大きく除去することができる。 Further, the firing is preferably performed at 500 ° C. or higher. By setting the firing temperature to 500 ° C. or higher, distortion after molding can be largely removed.
　また、シリコーン樹脂としては、例えば、メチル系シリコーン樹脂、メチルフェニル系シリコーン樹脂を用いることができる。無機絶縁粉末としては、例えば、二酸化ケイ素（シリカ、ＳｉＯ２）、酸化アルミニウム（アルミナ、Ａｌ２Ｏ３）、酸化マグネシウム（マグネシア、ＭｇＯ）を用いることができる。 Moreover, as a silicone resin, a methyl silicone resin and a methylphenyl silicone resin can be used, for example. As the inorganic insulating powder, for example, silicon dioxide (silica, SiO 2 ), aluminum oxide (alumina, Al 2 O 3 ), magnesium oxide (magnesia, MgO) can be used.
　本発明の複合軟磁性材料の組織は、軟磁性粉末粒子間のシリコーン樹脂および無機絶縁粉末からなる絶縁層の厚さが均一であることが好ましい。 In the structure of the composite soft magnetic material of the present invention, it is preferable that the thickness of the insulating layer made of the silicone resin and the inorganic insulating powder between the soft magnetic powder particles is uniform.
　その状態は断面観察において、偏析の厚い部分の厚みを１つの軟磁性粉末粒子について２箇所測定し、これを２０粒子以上について測定を行い、平均値を算出した平均偏析厚さＤにより判別できる。絶縁層の厚さが均一な状態は軟磁性粉末粒子間の平均偏析厚さＤが小さく、理想的な状態では絶縁層と同じ厚さになる。一方絶縁層の厚さが均一でない状態はシリコーン樹脂および無機絶縁粉末が三重点などの局所に集中し、その結果偏析部分が厚くなって平均偏析厚さＤが大きくなり、軟磁性粉末粒子間の絶縁層のシリコーン樹脂および無機絶縁粉末がその偏析部分に奪われるため絶縁層の厚さは薄くなる。 The state can be discriminated by the average segregation thickness D obtained by measuring the thickness of the thickly segregated portion at two locations for one soft magnetic powder particle, measuring 20 or more particles, and calculating the average value in cross-sectional observation. When the thickness of the insulating layer is uniform, the average segregation thickness D between the soft magnetic powder particles is small. In an ideal state, the thickness is the same as that of the insulating layer. On the other hand, when the thickness of the insulating layer is not uniform, the silicone resin and the inorganic insulating powder are concentrated locally such as triple points. As a result, the segregation part becomes thick and the average segregation thickness D increases, and the soft magnetic powder particles Since the silicone resin and inorganic insulating powder of the insulating layer are deprived by the segregated portion, the thickness of the insulating layer is reduced.
　平均偏析厚さＤはシリコーン樹脂と無機絶縁粉末の添加総量Ｘ質量％につれて増減するが、Ｘの５倍以下であればおおよそ均一な状態であると言える。 The average segregation thickness D increases and decreases with the total amount X mass% added of the silicone resin and the inorganic insulating powder, but it can be said that the average segregation thickness D is approximately uniform when it is 5 times or less of X.
　しかし平均偏析厚さＤがＸの５倍を超えると絶縁層の偏析部分が厚くなる一方、軟磁性粉末粒子間の絶縁層は薄くなりすぎるため、絶縁が不完全になって比抵抗が低下したり、あるいは軟磁性粉末粒子間のギャップが充分形成されずに直流重畳特性が悪化したりする。 However, when the average segregation thickness D exceeds 5 times X, the segregation part of the insulating layer becomes thicker, while the insulating layer between the soft magnetic powder particles becomes too thin, so that the insulation becomes incomplete and the specific resistance decreases. Or, the gap between the soft magnetic powder particles is not sufficiently formed, and the direct current superimposition characteristic is deteriorated.
　よって平均偏析厚さＤ（μｍ）はシリコーン樹脂と無機絶縁粉末の総量Ｘ質量％の５倍以下、さらに好ましくは４倍以下とする。 Therefore, the average segregation thickness D (μm) is 5 times or less, more preferably 4 times or less of the total amount X mass% of the silicone resin and the inorganic insulating powder.
　以下、本発明の複合軟磁性材料及びその製造方法の具体的な実施例について説明する。なお、本発明は、以下の実施例に限定されるものではなく、種々の変形実施が可能である。 Hereinafter, specific examples of the composite soft magnetic material of the present invention and the manufacturing method thereof will be described. In addition, this invention is not limited to a following example, A various deformation | transformation implementation is possible.
　軟磁性粉末として、平均粒径が約５０μｍのリン酸塩被覆処理が施された水アトマイズ純鉄粉（ヘガネスジャパン社製　Ｓ１１０ｉ）を用いた。シリコーン樹脂として、メチルフェニル系（信越化学社製　ＫＲレジン）を用いた。また、無機絶縁粉末として、比表面積が１７０～１８０ｍ２／ｇ、平均粒径が約１２ｎｍの疎水性のシリカ粉末（日本アエロジル社製　Ｒ９７４）を用いた。 As the soft magnetic powder, water atomized pure iron powder (S110i, manufactured by Höganäs Japan Co., Ltd.) subjected to a phosphate coating treatment with an average particle size of about 50 μm was used. As the silicone resin, methylphenyl type (KR resin manufactured by Shin-Etsu Chemical Co., Ltd.) was used. As the inorganic insulating powder, hydrophobic silica powder (R974 manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 170 to 180 m 2 / g and an average particle diameter of about 12 nm was used.
　はじめに、軟磁性粉末と、軟磁性粉末に対して０．７質量％（ただし、溶媒を除いた溶質の量とする）のシリコーン樹脂とを均一に混合して、攪拌しながら５０℃で０．５時間の乾燥を行って、軟磁性粉末をシリコーン樹脂で被覆した被覆粉末を得た。 First, the soft magnetic powder and 0.7% by mass (however, the amount of solute excluding the solvent) of the soft magnetic powder are uniformly mixed and stirred at 50 ° C. with stirring at 50 ° C. Drying for 5 hours was performed to obtain a coated powder obtained by coating a soft magnetic powder with a silicone resin.
　つぎに、この被覆粉末と、軟磁性粉末に対して０．５質量％の無機絶縁粉末とを均一に混合した。このときの粉末は、図１に示すように、軟磁性粉末１を被覆したシリコーン樹脂２の外側に無機絶縁粉末３が付着している。さらに軟磁性粉末に対して０．８質量％の粉末冶金用ワックス系潤滑剤を添加して、その混合物を成形圧８ｔ／ｃｍ２で成形後、６２０℃の窒素雰囲気中で３０分間の焼成を行った（実施例Ａ）。或いは、この被覆粉末と、軟磁性粉末に対して１．０質量％の無機絶縁粉末とを均一に混合し、さらに軟磁性粉末に対して０．８質量％の粉末冶金用ワックス系潤滑剤を添加して、その混合物を成形圧８ｔ／ｃｍ２で成形後、６２０℃の窒素雰囲気中で３０分間の焼成を行った（実施例Ｂ）。また、比較例として、無機絶縁粉末を混合しないほかは上記と同様にして焼成を行った（比較例ａ）。 Next, the coating powder and an inorganic insulating powder of 0.5% by mass with respect to the soft magnetic powder were uniformly mixed. As shown in FIG. 1, the inorganic insulating powder 3 adheres to the outside of the silicone resin 2 coated with the soft magnetic powder 1. Further, 0.8% by mass of a wax-based lubricant for powder metallurgy is added to the soft magnetic powder, and the mixture is molded at a molding pressure of 8 t / cm 2 and then fired in a nitrogen atmosphere at 620 ° C. for 30 minutes. (Example A). Alternatively, this coating powder is uniformly mixed with 1.0% by mass of an inorganic insulating powder with respect to the soft magnetic powder, and further 0.8% by mass of a wax-based lubricant for powder metallurgy with respect to the soft magnetic powder. The mixture was added and the mixture was molded at a molding pressure of 8 t / cm 2 and then fired in a nitrogen atmosphere at 620 ° C. for 30 minutes (Example B). Further, as a comparative example, firing was performed in the same manner as above except that the inorganic insulating powder was not mixed (Comparative Example a).
　以上の操作により、それぞれφ３５×φ２５×５ｍｍのトロイダル形状の試料を作製し、巻線（巻線数Ｎ＝５０ターン）を施し、ＬＣＲメーター（アジレント社製　４２４８Ａ）を使用して０～２０ｋＡ／ｍの直流磁界中にて交流１０ｋＨｚのインダクタンスを測定することにより、直流重畳特性を評価した。その結果を図３に示す。実施例Ａ、Ｂともに、広い磁界範囲においても比較例ａよりもインダクタンスの低下率が低く、良好な直流重畳特性を有することが確認された。 By the above operations, toroidal samples of φ35 × φ25 × 5 mm were prepared, wound (number of windings N = 50 turns), and 0-20 kA / using an LCR meter (Agilent 4248A). The DC superposition characteristics were evaluated by measuring the inductance of AC 10 kHz in a DC magnetic field of m. The result is shown in FIG. In both Examples A and B, the rate of decrease in inductance was lower than that in Comparative Example a even in a wide magnetic field range, and it was confirmed that the examples had good DC superposition characteristics.
　また、巻線（１次巻線数Ｎ１＝５０、２次巻線数Ｎ２＝５０）を施して、１００ｍＴ、１０ｋＨｚにおける鉄損（Ｐｃ）を測定したところ、２１．４Ｗ／ｋｇであった。また、同様の条件において、ヒステリス損失（Ｐｈ）は１７．１Ｗ／ｋｇ、渦電流損失（Ｐｅ）は３．６Ｗ／ｋｇであった。 Moreover, when the winding (primary winding number N1 = 50, secondary winding number N2 = 50) was applied and the iron loss (Pc) at 100 mT and 10 kHz was measured, it was 21.4 W / kg. Under the same conditions, the hysteresis loss (Ph) was 17.1 W / kg, and the eddy current loss (Pe) was 3.6 W / kg.
　無機絶縁粉末を混合するタイミングが、試料の密度、比抵抗、透磁率に及ぼす影響について検討した。原料は実施例１と同様のものを用い、条件は明記しない限り実施例１と同様とした。 The influence of the timing of mixing the inorganic insulating powder on the density, specific resistance, and magnetic permeability of the sample was examined. The raw materials were the same as in Example 1 and the same as in Example 1 unless conditions were specified.
　（１）実施例Ｃ
　はじめに、軟磁性粉末と、軟磁性粉末に対して０．７質量％のシリコーン樹脂とを均一に混合して、攪拌しながら乾燥を行って、軟磁性粉末をシリコーン樹脂で被覆した被覆粉末を得た。 (1) Example C
First, a soft magnetic powder and 0.7% by mass of a silicone resin with respect to the soft magnetic powder are uniformly mixed and dried while stirring to obtain a coated powder in which the soft magnetic powder is coated with the silicone resin. It was.
　つぎに、この被覆粉末と、軟磁性粉末に対して０．５質量％の無機絶縁粉末とを均一に混合した。このときの粉末は、図４（ａ）に示すように、軟磁性粉末を被覆したシリコーン樹脂の外側に無機絶縁粉末が付着している。 Next, this coating powder and an inorganic insulating powder of 0.5% by mass with respect to the soft magnetic powder were uniformly mixed. At this time, as shown in FIG. 4A, the inorganic insulating powder adheres to the outside of the silicone resin coated with the soft magnetic powder.
　さらに、軟磁性粉末に対して０．８質量％の潤滑剤を添加して、その混合物を成形圧８ｔ／ｃｍ２又は１２ｔ／ｃｍ２で成形後、６２０℃の窒素雰囲気中で３０分間の焼成を行った。 Further, 0.8% by mass of lubricant is added to the soft magnetic powder, and the mixture is molded at a molding pressure of 8 t / cm 2 or 12 t / cm 2 and then fired in a nitrogen atmosphere at 620 ° C. for 30 minutes. Went.
　以上の操作により、それぞれφ３５×φ２５×５ｍｍのトロイダル形状の試料を作製し、巻線（巻線数Ｎ＝５０ターン）を施し、ＬＣＲメーターを使用してインダンクタンスを測定することにより、直流重畳特性を測定した。また、試料の密度を測定するとともに、ＢＨトレーサーを使用して最大比透磁率を測定した。 By the above operation, a toroidal sample of φ35 × φ25 × 5 mm is prepared, wound (number of windings N = 50 turns), and the inductance is measured using an LCR meter. The superposition characteristics were measured. Moreover, while measuring the density of the sample, the maximum relative magnetic permeability was measured using a BH tracer.
　また、それぞれ６０×１０×５ｍｍのバー形状の試料を作製し、４端子法で比抵抗値を測定した。 Also, each 60 × 10 × 5 mm bar-shaped sample was prepared, and the specific resistance value was measured by a four-terminal method.
　（２）比較例ｂ
　はじめに、軟磁性粉末と、軟磁性粉末に対して０．５質量％の無機絶縁粉末とを均一に混合し、無機絶縁粉末が付着した軟磁性粉末を得た。 (2) Comparative example b
First, soft magnetic powder and 0.5% by mass of inorganic insulating powder with respect to soft magnetic powder were uniformly mixed to obtain soft magnetic powder to which inorganic insulating powder was adhered.
　つぎに、無機絶縁粉末が付着した軟磁性粉末と、軟磁性粉末に対して０．７質量％のシリコーン樹脂とを均一に混合して、攪拌しながら乾燥を行って、無機絶縁粉末が付着した軟磁性粉末をシリコーン樹脂で被覆した被覆粉末を得た。このときの粉末は、図４（ｂ）に示すように、軟磁性粉末の外側に無機絶縁粉末が付着し、その外側にシリコーン樹脂が被覆されている。 Next, the soft magnetic powder to which the inorganic insulating powder was adhered and 0.7% by mass of the silicone resin with respect to the soft magnetic powder were uniformly mixed and dried while stirring, so that the inorganic insulating powder was adhered. A coated powder obtained by coating a soft magnetic powder with a silicone resin was obtained. As shown in FIG. 4B, the powder at this time has an inorganic insulating powder attached to the outside of the soft magnetic powder, and the outside is covered with a silicone resin.
　さらに、軟磁性粉末に対して０．８質量％の潤滑剤を添加して、その混合物を成形圧８ｔ／ｃｍ２又は１２ｔ／ｃｍ２で成形後、６２０℃の窒素雰囲気中で３０分間の焼成を行った。 Further, 0.8% by mass of lubricant is added to the soft magnetic powder, and the mixture is molded at a molding pressure of 8 t / cm 2 or 12 t / cm 2 and then fired in a nitrogen atmosphere at 620 ° C. for 30 minutes. Went.
　以上の操作により、それぞれφ３５×φ２５×５ｍｍのトロイダル形状の試料を作製し、巻線（巻線数Ｎ＝５０ターン）を施し、ＬＣＲメーターを使用してインダンクタンスを測定することにより、直流重畳特性を測定した。また、試料の密度を測定するとともに、ＢＨトレーサーを使用して最大比透磁率を測定した。 By the above operation, a toroidal sample of φ35 × φ25 × 5 mm is prepared, wound (number of windings N = 50 turns), and the inductance is measured using an LCR meter. The superposition characteristics were measured. Moreover, while measuring the density of the sample, the maximum relative magnetic permeability was measured using a BH tracer.
　また、それぞれ６０×１０×５ｍｍのバー形状の試料を作製し、４端子法で比抵抗値を測定した。 Also, each 60 × 10 × 5 mm bar-shaped sample was prepared, and the specific resistance value was measured by a four-terminal method.
　（３）比較例ｃ
　軟磁性粉末と、軟磁性粉末に対して０．７質量％のシリコーン樹脂と、軟磁性粉末に対して０．５質量％の無機絶縁粉末とを均一に混合して、攪拌しながら乾燥を行って、軟磁性粉末をシリコーン樹脂と無機絶縁粉末の混合物で被覆した被覆粉末を得た。このときの粉末は、図４（ｃ）に示すように、軟磁性粉末の外側にシリコーン樹脂と無機絶縁粉末の混合物が被覆されている。 (3) Comparative example c
Soft magnetic powder, 0.7% by mass of silicone resin with respect to soft magnetic powder, and 0.5% by mass of inorganic insulating powder with respect to soft magnetic powder are uniformly mixed and dried with stirring. Thus, a coating powder obtained by coating the soft magnetic powder with a mixture of silicone resin and inorganic insulating powder was obtained. As shown in FIG. 4C, the powder at this time is coated with a mixture of a silicone resin and an inorganic insulating powder on the outside of the soft magnetic powder.
　そして、軟磁性粉末に対して０．８質量％の潤滑剤を添加して、その混合物を成形圧８ｔ／ｃｍ２又は１２ｔ／ｃｍ２で成形後、６２０℃の窒素雰囲気中で３０分間の焼成を行った。 Then, 0.8% by mass of a lubricant is added to the soft magnetic powder, and the mixture is molded at a molding pressure of 8 t / cm 2 or 12 t / cm 2 and then fired in a nitrogen atmosphere at 620 ° C. for 30 minutes. Went.
　以上の操作により、それぞれφ３５×φ２５×５ｍｍのトロイダル形状の試料を作製し、巻線（巻線数Ｎ＝５０ターン）を施し、ＬＣＲメーターを使用してインダクタンスを測定することにより、直流重畳特性を測定した。また、試料の密度を測定するとともに、ＢＨトレーサーを使用して最大比透磁率を測定した。 By the above operation, φ35 × φ25 × 5mm toroidal samples are prepared, windings (number of windings N = 50 turns) are applied, and inductance is measured using an LCR meter. Was measured. Moreover, while measuring the density of the sample, the maximum relative magnetic permeability was measured using a BH tracer.
　また、それぞれ６０×１０×５ｍｍのバー形状の試料を作製し、４端子法で比抵抗値を測定した。 Also, each 60 × 10 × 5 mm bar-shaped sample was prepared, and the specific resistance value was measured by a four-terminal method.
　（４）結果
　結果を図５～８に示す。実施例Ｃは、広い磁界範囲において比較例ｂ、ｃよりもインダクタンスの低下率が低く、良好な直流重畳特性を有することが確認された。密度については、実施例Ｃ、比較例ｂ、ｃの間に顕著な差は見られなかった。比抵抗については、比較例ｂ、ｃと比べて実施例Ｃにおいて顕著に高い値となり、最大比透磁率については、比較例ｂ、ｃと比べて実施例Ｃにおいて顕著に低い値となった。また、実施例Ｃにおいては、成形圧により比抵抗と最大比透磁率が変化することはなかった。 (4) Results The results are shown in FIGS. In Example C, it was confirmed that the rate of decrease in inductance was lower than that in Comparative Examples b and c in a wide magnetic field range, and had good DC superposition characteristics. Regarding the density, no significant difference was observed between Example C and Comparative Examples b and c. The specific resistance was significantly higher in Example C than in Comparative Examples b and c, and the maximum specific permeability was significantly lower in Example C than in Comparative Examples b and c. In Example C, the specific resistance and the maximum relative permeability did not change with the molding pressure.
　以上より、軟磁性粉末をシリコーン樹脂で被覆して得た被覆粉末と、無機絶縁粉末とを均一に混合し、その混合物を成形、焼成することにより、成形圧に関わらず特性の優れた複合軟磁性材料が得られることが確認された。 As described above, a composite powder obtained by coating a soft magnetic powder with a silicone resin and an inorganic insulating powder are uniformly mixed, and the mixture is molded and fired. It was confirmed that a magnetic material was obtained.
　実施例２の実施例Ｃと比較例ｂにおいて作製した試料について、断面を顕微鏡により観察した。その結果を図９に示す。図９（ａ）は実施例Ｃ、図９（ｂ）は比較例ｂの写真である。 For the samples prepared in Example C of Example 2 and Comparative Example b, the cross section was observed with a microscope. The result is shown in FIG. 9A is a photograph of Example C, and FIG. 9B is a photograph of Comparative Example b.
　比較例ｂによる図９（ｂ）では、軟磁性粉末粒子間に無機絶縁粉末の凝集による不良部分（図中、矢印部分）が多数見られた。 In FIG. 9B according to Comparative Example b, a number of defective portions (arrow portions in the figure) due to the aggregation of the inorganic insulating powder were observed between the soft magnetic powder particles.
　この無機絶縁粉末が部分的に凝集して偏析していることにより、無機絶縁粉末およびシリコーン樹脂が軟磁性粉末粒子間に十分行き渡っておらず、そのため絶縁層の厚さが不均一になり、部分的に薄くなって比抵抗が低下したり、軟磁性粉末粒子間のギャップを十分保てずに直流重畳特性が悪化したと考えられる。 Since this inorganic insulating powder is partially aggregated and segregated, the inorganic insulating powder and the silicone resin are not sufficiently distributed between the soft magnetic powder particles, so that the thickness of the insulating layer becomes uneven, Therefore, it is considered that the specific resistance is lowered, the specific resistance is lowered, or the gap between the soft magnetic powder particles is not sufficiently maintained, and the direct current superimposition characteristic is deteriorated.
　一方、本発明の実施例Ｃによる図９（ａ）は無機絶縁粉末の凝集による不良部分が少なく、このことから本発明では無機絶縁粉末およびシリコーン樹脂が軟磁性粉末粒子間に十分行き渡っており、これにより絶縁層の厚さが均一になって、高い比抵抗を保ち、且つ、軟磁性粉末粒子間のギャップを十分保つことができたことにより良好な直流重畳特性が得られたと考えられる。 On the other hand, FIG. 9A according to Example C of the present invention has few defective portions due to aggregation of the inorganic insulating powder, and in the present invention, the inorganic insulating powder and the silicone resin are sufficiently distributed between the soft magnetic powder particles. As a result, the thickness of the insulating layer becomes uniform, a high specific resistance can be maintained, and a sufficient gap between the soft magnetic powder particles can be maintained, so that it is considered that good direct current superposition characteristics are obtained.
　また、複合軟磁性材料の軟磁性粉末粒子間のシリコーン樹脂および無機絶縁粉末からなる絶縁層の厚さの均一性を評価するため、平均偏析厚さを測定した。 In addition, in order to evaluate the uniformity of the thickness of the insulating layer made of the silicone resin and the inorganic insulating powder between the soft magnetic powder particles of the composite soft magnetic material, the average segregation thickness was measured.
　測定方法は、図１０に示すように、断面観察において、シリコーン樹脂および無機絶縁粉末からなる絶縁層の偏析の厚い部分の厚みを１つの軟磁性粉末粒子について２箇所測定し、これを２０粒子について測定を行い、平均値を算出した。すなわち、シリコーン樹脂および無機絶縁粉末からなる絶縁層において、１つの軟磁性粉末粒子について、隣接した任意の軟磁性粉末粒子との間に形成された間隙ののうち、最も大きい間隙の大きさと、２番目に大きい間隙の大きさを測定し、これを２０粒子について測定を行い、平均値を算出した。その結果を表１に示す。 As shown in FIG. 10, in the cross-sectional observation, the thickness of the thick part of the segregation of the insulating layer made of the silicone resin and the inorganic insulating powder is measured at two locations for one soft magnetic powder particle as shown in FIG. Measurement was performed and an average value was calculated. That is, in the insulating layer made of silicone resin and inorganic insulating powder, the size of the largest gap among the gaps formed between any soft magnetic powder particles adjacent to one soft magnetic powder particle, and 2 The size of the second largest gap was measured, 20 particles were measured, and the average value was calculated. The results are shown in Table 1.
　実施例Ｃの平均偏析厚さは３．８μｍで、比較例ｂの平均偏析厚さの７．８μｍよりも小さな値であった。このことから実施例Ｃは軟磁性粉末粒子間の絶縁層の偏析が少なく、従って絶縁層の厚さが均一であることが確認された。 The average segregation thickness of Example C was 3.8 μm, which was smaller than the average segregation thickness of Comparative Example b of 7.8 μm. From this, it was confirmed that Example C had little segregation of the insulating layer between the soft magnetic powder particles, and therefore the thickness of the insulating layer was uniform.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　種々の軟磁性材料、シリコーン樹脂（シリコーンレジン）、無機絶縁粉末を用い、これらの配合量、焼成温度を変化させて、複合軟磁性材料を作成し、性能を評価した。その結果を表に示す。また、それぞれの複合軟磁性材料の断面組織観察で、シリコーン樹脂および無機絶縁粉末からなる絶縁層の偏析の厚い部分の厚みを１つの軟磁性粉末粒子について２箇所測定し、これを２０粒子以上について測定を行い、平均偏析厚さＤ（μｍ）を求めた。すなわち、シリコーン樹脂および無機絶縁粉末からなる絶縁層において、１つの軟磁性粉末粒子について、隣接した任意の軟磁性粉末粒子との間に形成された間隙ののうち、最も大きい間隙の大きさと、２番目に大きい間隙の大きさを測定し、これを２０粒子について測定を行い、平均偏析厚さＤ（μｍ）を求めた。さらに、シリコーン樹脂と無機絶縁粉末の総量Ｘ質量％に対する平均偏析厚さＤの比率、Ｄ／Ｘを求めた。その結果を表に示す。なお、複合軟磁性材料の作製は、下記の表に示す条件のほかは、上記実施例１と同様の条件のもとで行った。特性値として、比抵抗、高磁界域（１０ｋＡ／ｍ）でのインダクタンスＬ、並びに、直流重畳特性として０～５．３ｋＡ／ｍにかけてのインダクタンスＬの低下率で比較した。 Using various soft magnetic materials, silicone resin (silicone resin), and inorganic insulating powder, and changing the blending amount and firing temperature of these, composite soft magnetic materials were prepared and their performance was evaluated. The results are shown in the table. In addition, by observing the cross-sectional structure of each composite soft magnetic material, the thickness of the segregated thick portion of the insulating layer made of silicone resin and inorganic insulating powder was measured at two locations for one soft magnetic powder particle, and this was measured for 20 particles or more. Measurement was performed to determine an average segregation thickness D (μm). That is, in the insulating layer made of silicone resin and inorganic insulating powder, the size of the largest gap among the gaps formed between any soft magnetic powder particles adjacent to one soft magnetic powder particle, and 2 The size of the second largest gap was measured, and this was measured for 20 particles to determine the average segregation thickness D (μm). Further, the ratio of the average segregation thickness D to the total amount X mass% of the silicone resin and the inorganic insulating powder, D / X, was obtained. The results are shown in the table. The composite soft magnetic material was produced under the same conditions as in Example 1 except for the conditions shown in the following table. The characteristic values were compared in terms of specific resistance, inductance L in a high magnetic field region (10 kA / m), and direct current superposition characteristics in terms of the rate of decrease in inductance L from 0 to 5.3 kA / m.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　軟磁性材料としては、リン酸鉄膜又は酸化マグネシウム（ＭｇＯ）膜により被覆されたものを用いた。シリコーン樹脂としては、メチルフェニル系の軟質（硬さ３．９ＭＨｖ）のもの（表中Ａ）、メチル系の軟質（硬さ５．０ＭＨｖ）のもの（表中Ｂ）、メチル系アルキルの硬質（硬さ８．９ＭＨｖ）のもの（表中Ｃ）を用いた。無機絶縁粉末としては、二酸化ケイ素（ＳｉＯ２）、酸化アルミニウム（Ａｌ２Ｏ３）、酸化マグネシウム（ＭｇＯ）を用いた。 As the soft magnetic material, a material coated with an iron phosphate film or a magnesium oxide (MgO) film was used. Silicone resins include methylphenyl soft (hardness 3.9 MHv) (A in the table), methyl soft (hardness 5.0 MHv) (B in the table), methyl alkyl hard ( The one having a hardness of 8.9 MHv (C in the table) was used. As the inorganic insulating powder, silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), and magnesium oxide (MgO) were used.
　軟磁性粉末の平均粒径が１０～１００μｍであって、無機絶縁粉末の平均粒径が１μｍ以下であって、シリコーン樹脂と無機絶縁粉末の総量（添加総量）が軟磁性粉末に対して０．３～２質量％であって、シリコーン樹脂の量が軟磁性粉末に対して０．１５～１．２質量％、無機絶縁粉末の量が軟磁性粉末に対して０．１～１質量％であって、無機絶縁粉末の添加が軟磁性粉末をシリコーン樹脂で被覆した後であって、かつ、焼成が５００℃以上で行われたときに（実施例Ｃ～Ｒ）、良好な特性値が得られた。また、良好な特性を示した複合軟磁性材料（実施例Ｃ～Ｒ）の平均偏析厚さＤの添加総量Ｘ質量％に対する比Ｄ／Ｘは、いずれも５以下であった。 The average particle diameter of the soft magnetic powder is 10 to 100 μm, the average particle diameter of the inorganic insulating powder is 1 μm or less, and the total amount (addition total amount) of the silicone resin and the inorganic insulating powder is 0. 3 to 2% by mass, the amount of the silicone resin is 0.15 to 1.2% by mass with respect to the soft magnetic powder, and the amount of the inorganic insulating powder is 0.1 to 1% by mass with respect to the soft magnetic powder. When the inorganic insulating powder is added after the soft magnetic powder is coated with the silicone resin and firing is performed at 500 ° C. or higher (Examples C to R), good characteristic values are obtained. It was. In addition, the ratio D / X of the average segregation thickness D of the composite soft magnetic materials (Examples C to R) exhibiting good characteristics to the total amount of added X mass% was 5 or less in all cases.
　なお、比抵抗については、磁路断面１辺５０ｍｍのリアクトルで（粒間の渦損）／（全体の渦損）を５％と定めた場合に２Ωｍの比抵抗値が必要となるため、２Ωｍ以上の場合に良好と判定した。インダクタンス（Ｌ）については、高磁界域（１０ｋＡ／ｍ）での値が市販ダストコアよりも１０％以上向上した場合に良好と判定した。また、インダクタンス低下率（Ｌ低下率）については、φ３５×φ２５×５ｍｍのトロイダル形状の試料に巻線（巻線数Ｎ＝５０ターン）を施して１０Ａの電流を流して磁界を印加したとき（磁界５．３ｋＡ／ｍ）、印加前に比べてインダクタンス低下率が３０％以下の場合に良好と判断した。インダクタンス低下率が３０％を超えるとギャップ加工又は部品増加が必要な設計となるので好ましくない。 As for the specific resistance, a specific resistance value of 2 Ωm is required when a reactor having a magnetic path cross section of 1 side of 50 mm and (vortex loss between grains) / (total vortex loss) is set to 5%. In the above cases, it was determined to be good. The inductance (L) was determined to be good when the value in the high magnetic field region (10 kA / m) was improved by 10% or more than the commercially available dust core. As for the inductance reduction rate (L reduction rate), when a magnetic field is applied by applying a winding (number of windings N = 50 turns) to a toroidal sample of φ35 × φ25 × 5 mm and flowing a current of 10 A ( The magnetic field was 5.3 kA / m), and when the inductance reduction rate was 30% or less compared to before application, it was judged good. If the inductance reduction rate exceeds 30%, it is not preferable because it requires a gap machining or an increase in parts.
１　軟磁性粉末
２　シリコーン樹脂
３　無機絶縁粉末
４　絶縁被膜 1 Soft magnetic powder 2 Silicone resin 3 Insulating insulating powder 4 Insulating coating

Claims (5)

  1. 絶縁被膜により被覆された軟磁性粉末をシリコーン樹脂で被覆して得た被覆粉末と、無機絶縁粉末とを均一に混合し、その混合物を成形、焼成することにより得られ、前記シリコーン樹脂と前記無機絶縁粉末の総量をＸ質量％としたとき、断面観察において、シリコーン樹脂および無機絶縁粉末からなる絶縁層の偏析の厚い部分の厚みを１つの軟磁性粉末粒子について２箇所測定し、これを２０粒子以上について測定して平均した平均偏析厚さＤ(μｍ）は、Ｘの５倍以下であることを特徴とする複合軟磁性材料。 A coating powder obtained by coating a soft magnetic powder coated with an insulating coating with a silicone resin and an inorganic insulating powder are uniformly mixed, and the mixture is molded and fired to obtain the silicone resin and the inorganic powder. When the total amount of the insulating powder is X mass%, in the cross-sectional observation, the thickness of the thick segregated portion of the insulating layer made of the silicone resin and the inorganic insulating powder is measured at two locations for one soft magnetic powder particle, and this is 20 particles. A composite soft magnetic material characterized in that an average segregation thickness D (μm) measured and averaged for the above is not more than 5 times X.
  2. 前記軟磁性粉末は平均粒径１０～１００μｍの純鉄粉であり、前記無機絶縁粉末の平均粒径は１μｍ以下であり、前記シリコーン樹脂と前記無機絶縁粉末の総量は前記軟磁性粉末に対して０．３～２質量％であることを特徴とする請求項１記載の複合軟磁性材料。 The soft magnetic powder is pure iron powder having an average particle size of 10 to 100 μm, the average particle size of the inorganic insulating powder is 1 μm or less, and the total amount of the silicone resin and the inorganic insulating powder is based on the soft magnetic powder. 2. The composite soft magnetic material according to claim 1, wherein the content is 0.3 to 2% by mass.
  3. 前記シリコーン樹脂と前記無機絶縁粉末の総量のうち、前記シリコーン樹脂の量は前記軟磁性粉末に対して０．１５～１．２質量％、前記無機絶縁粉末の量は前記軟磁性粉末に対して０．１～１質量％であることを特徴とする請求項２記載の複合軟磁性材料。 Of the total amount of the silicone resin and the inorganic insulating powder, the amount of the silicone resin is 0.15 to 1.2% by mass based on the soft magnetic powder, and the amount of the inorganic insulating powder is based on the soft magnetic powder. 3. The composite soft magnetic material according to claim 2, wherein the content is 0.1 to 1% by mass.
  4. 前記絶縁被膜はリン酸鉄膜又は酸化マグネシウム膜であることを特徴とする請求項１～３のいずれか１項記載の複合軟磁性材料。 The composite soft magnetic material according to any one of claims 1 to 3, wherein the insulating coating is an iron phosphate film or a magnesium oxide film.
  5. 絶縁被膜により被覆された軟磁性粉末をシリコーン樹脂で被覆して被覆粉末を得た後、被覆粉末と無機絶縁粉末とを均一に混合し、その混合物を成形、焼成することを特徴とする複合軟磁性材料の製造方法。 A soft magnetic powder coated with an insulating film is coated with a silicone resin to obtain a coated powder, and then the coated powder and the inorganic insulating powder are uniformly mixed, and the mixture is molded and fired. Manufacturing method of magnetic material.
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