JP4586399B2 - 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 for producing a soft magnetic material, and more specifically, a soft magnetic material, a dust core, and a soft magnetic that can improve AC magnetic characteristics and moldability. The present invention relates to a material manufacturing method.

  A soft magnetic material is used for an electric device having a solenoid valve, a motor, a power supply circuit, or the like. This soft magnetic material is composed of a plurality of composite magnetic particles, and the composite magnetic particles have metal magnetic particles made of, for example, pure iron, and an insulating film made of, for example, phosphate that covers the surface thereof. . The soft magnetic material is required to have a magnetic characteristic that can obtain a large magnetic flux density by applying a small magnetic field and can react sensitively to a magnetic field change from the outside.

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

The dust core is required to have magnetic characteristics that reduce the occurrence of iron loss, that is, high AC magnetic characteristics. To achieve this, the magnetic permeability μ of the soft magnetic material, to increase 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 material. Since pure iron, which is a raw material for conventional soft magnetic materials, has magnetic anisotropy, there has been a limit to improving the AC magnetic properties of soft magnetic materials made of pure iron.

As a method for improving the exchange magnetic properties of the powder magnetic core, the magnetic permeability μ is higher than that of pure iron, the method is conceivable to produce a soft magnetic material with a coercive force H _c is less permalloy and sendust. However, since the hardness of permalloy and sendust is very large compared to the hardness of pure iron, the soft magnetic material produced using permalloy and sendust has poor moldability, and as a result, the density of the resulting molded product is low. There was a problem.

Therefore, as a production method capable of improving the moldability of a soft magnetic material using sendust, sendust in a proportion of 65% to 98% by mass and highly compressible soft magnetism in a proportion of 2% to 35% by mass. For example, Japanese Patent Application Laid-Open No. 6-236808 (Patent Document 1) discloses a manufacturing method in which a mixture with a metal powder is bound by a binder.
JP-A-6-236808

  However, the saturation magnetic flux density Bs of the dust core made of pure iron is 2.15 T, whereas the saturation magnetic flux density Bs of the dust core of Patent Document 1 is 0.83 T or less, which is sufficient. Saturation magnetic flux density Bs was not obtained. This is due to the low saturation magnetic flux density Bs of Sendust. If the saturation magnetic flux density Bs is low, the AC magnetic field required to make the magnetic flux density of the dust core more than a certain value becomes large, and the AC magnetic characteristics are degraded. In particular, a powder magnetic core used for a motor, a power transformer core or the like requires a saturation magnetic flux density of at least 1.5 T, and the powder magnetic core disclosed in Patent Document 1 cannot obtain a sufficient saturation magnetic flux density Bs. .

  Moreover, since the soft magnetic material of the said patent document 1 has sendust as a main component, there existed a problem that a moldability was not enough.

  Accordingly, an object of the present invention is to solve the above-described problems, and to provide a soft magnetic material, a dust core, and a method for producing a soft magnetic material that can improve AC magnetic characteristics and formability. .

The soft magnetic material of the present invention is a soft magnetic material used for the production of a dust core, comprising iron particles having an insulating coating formed on the surface, and additive particles comprising at least one of Sendust or Permalloy. Contains. The additive particles are contained in a proportion of more than 0% by mass and 30% by mass or less. The insulating coating contains an aluminum phosphate compound and a calcium phosphate compound. A thermoplastic resin is further included at a ratio of 0.01% by mass to 0.1% by mass.

The method for producing a soft magnetic material of the present invention includes the following steps. A mixed powder is produced in which iron particles having an insulating coating formed on the surface and additive particles made of at least one of Sendust and Permalloy are mixed. The insulating coating contains an aluminum phosphate compound and a calcium phosphate compound. The mixed powder is pressure-molded to form a molded body. The molded body is heat treated. When preparing the mixed powder, the additive particles are mixed in a proportion of more than 0% by mass and not more than 30% by mass. When preparing the mixed powder, the thermoplastic resin is further mixed at a ratio of 0.01% by mass or more and 0.1% by mass or less.

  According to the soft magnetic material and the manufacturing method thereof of the present invention, when an AC magnetic field is applied to the soft magnetic material, sendust or permalloy contained in the soft magnetic material is easily magnetized, and the magnetized sendust or permalloy is surrounded by Promotes magnetization of iron. As a result, it is possible to obtain a soft magnetic material having high AC magnetic characteristics that cannot be achieved when made of pure iron. Moreover, the fall of the saturation magnetic flux density Bs by Sendust or Permalloy can be suppressed because the quantity of Sendust or Permalloy shall be 30 mass% or less. Furthermore, the fall of the moldability by Sendust or a permalloy can be suppressed because the quantity of Sendust or a permalloy shall be 30 mass% or less. Therefore, the moldability of the soft magnetic material can be improved.

  The soft magnetic material of the present invention preferably contains additive particles in a proportion of 5% by mass or more and 25% by mass or less.

  In the method for producing a soft magnetic material of the present invention, preferably, additive particles are mixed at a ratio of 5% by mass or more and 25% by mass or less when a mixed powder is produced.

  Thereby, the AC magnetic characteristics of the soft magnetic material can be further improved.

  The soft magnetic material of the present invention preferably further contains a thermoplastic resin in a proportion of 0.01% by mass or more and 0.1% by mass or less.

  In the soft magnetic material of the present invention, preferably, when the mixed powder is produced, the thermoplastic resin is further mixed at a ratio of 0.01% by mass or more and 0.1% by mass or less.

Thereby, the thermoplastic resin is in a state of being interposed between the iron particles and the additive particles.
By setting the ratio of the thermoplastic resin to 0.01% by mass or more, the thermoplastic resin bends between the iron particles and the additive particles under stress during the pressure molding, so that the iron particles and the additive particles It will function as a lubricant. Moreover, the insulation between iron particles can be improved. On the other hand, by setting the ratio of the thermoplastic resin to 0.1% by mass or less, the density of the magnetic part of the soft magnetic material can be increased, so that the AC magnetic characteristics can be kept high.

  In the method for producing a soft magnetic material of the present invention, preferably, a pressure of 980 MPa or more is applied to the mixed powder when forming a molded body.

  Thereby, since a soft magnetic material can be densified, saturation magnetic flux density Bs can be improved and an alternating current magnetic characteristic can be improved.

  By producing a dust core using the soft magnetic material of the present invention, a dust core having a saturation magnetic flux density of 1.5 T or more can be obtained.

  According to the soft magnetic material and the manufacturing method thereof of the present invention, when an AC magnetic field is applied to the soft magnetic material, sendust or permalloy contained in the soft magnetic material is easily magnetized, and the magnetized sendust or permalloy is surrounded by Promotes magnetization of iron. As a result, it is possible to obtain a dust core having high AC magnetic characteristics that cannot be reached when made of pure iron. Moreover, the fall of the saturation magnetic flux density Bs by Sendust or Permalloy can be suppressed because the quantity of Sendust or Permalloy shall be 30 mass% or less. Furthermore, the fall of the moldability by Sendust or a permalloy can be suppressed because the quantity of Sendust or a permalloy shall be 30 mass% or less. Therefore, the moldability of the soft magnetic material can be improved.

  In the present specification, “permalloy” means an alloy composed of Ni (nickel) and Fe (iron) in a proportion of 40% by mass or more and 50% by mass or less. “Sendust” means an alloy composed of Si (silicon) at a ratio of 4% by mass to 13% by mass, Al (aluminum) at 4% by mass to 7% by mass, and Fe. is doing.

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

  FIG. 1 is an enlarged schematic view showing a molded body produced by the method for producing a soft magnetic material in one embodiment of the present invention.

  Referring to FIG. 1, a soft magnetic material compact (dust core) is composed of a plurality of composite magnetic particles 30, and composite magnetic particles 30 are composed of two types of composite magnetic particles 30a and 30b. ing. The composite magnetic particle 30a has iron particles 10a as metal magnetic particles and an insulating coating 20a formed on the surface of the iron particles 10a. The composite magnetic particle 30b has additive particles 10b as metal magnetic particles and an insulating coating 20b formed on the surface of the additive particles 10b. The additive particles 10b are made of at least one of sendust and permalloy. The additive particles 10b are contained in the soft magnetic material in a proportion of greater than 0% by mass and 30% by mass or less, preferably 5% by mass to 25% by mass. An organic substance 40 is interposed between each of the plurality of composite magnetic particles 30. Each of the plurality of composite magnetic particles 30 is joined by the organic material 40 or joined by meshing the unevenness of the composite magnetic particle 30. The organic substance 40 is contained in the soft magnetic material at a ratio of 0.01% by mass or more and 0.1% by mass or less.

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

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

  The insulating coatings 20a and 20b are made of an insulator containing, for example, an aluminum phosphate compound and a calcium phosphate compound. When the additive particles 10b are made of Sendust, an Al oxide film contained in Sendust may be used as the insulating coating 20b. The insulating coatings 20a and 20b function as an insulating layer between the iron particles 10a and the additive particles 10b. By covering the iron particles 10a and the additive particles 10b with the insulating coatings 20a and 20b, the electrical resistivity ρ of the soft magnetic material can be increased. Thereby, it can suppress that an eddy current flows between the iron particle 10a and the additive particle 10b, and can reduce the iron loss resulting from the eddy current loss of a soft magnetic material.

  The thickness of the insulating coatings 20a and 20b 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 coatings 20a and 20b to 20 μm or less, the ratio of the insulating coatings 20a and 20b in the soft magnetic material does not become too large. For this reason, it can prevent that the magnetic flux density of a soft-magnetic material falls remarkably.

  The organic substance 40 is made of a thermoplastic resin such as thermoplastic polyimide, thermoplastic polyamide, thermoplastic polyamideimide, polyethylene, polyphenylene sulfide, polyamideimide, polyethersulfone, polyetherimide, or polyetheretherketone.

  In the present embodiment, the case where the insulating coating 20b is formed on the surface of the additive particle 10b has been described. However, the insulating coating 20b may not be formed on the surface of the additive particle 10b. Moreover, in this Embodiment, although the case where the organic substance 40 intervened between each of the some composite magnetic particle 30 was shown, the organic substance 40 does not need to be.

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

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

  Referring to FIG. 2, first, iron particles 10a are prepared and heat-treated at a temperature of 400 ° C. or higher and lower than 900 ° C. The heat treatment temperature is more preferably 700 ° C. or higher and lower than 900 ° C. Many strains (dislocations and defects) exist in the iron particles 10a before the heat treatment. This distortion can be reduced by performing heat treatment on the iron particles 10a. Next, for example, the iron particles 10a are immersed in an aqueous solution in which the components of the insulating film 20a are dissolved, and then dried, thereby forming the insulating film 20a on the surface of the iron particles 10a (step S1a). Thereby, the composite magnetic particle 30a is obtained.

  On the other hand, additive particles 10b made of at least one of Sendust and Permalloy are prepared and heat-treated by the same method as that for the iron particles 10a. Next, the insulating coating 20b is formed on the surface of the additive particle 10b by the same method as that for the iron particle 10a (step S1b). Thereby, the composite magnetic particle 30b is obtained.

  As described above, the step of forming the insulating coating 20a on the surface of the iron particles 10a (step S1a) and the step of forming the insulating coating 20b on the additive particles 10b (step S1b) are performed separately, thereby providing the iron particles 10a. Even when the particle size of the additive particles 10b and the particle size of the additive particles 10b are greatly different, a uniform insulating coating can be formed on each particle.

  Next, the composite magnetic particle 30a, the composite magnetic particle 30b, and the organic substance 40 made of a thermoplastic resin are mixed (step S1c). The ratio of the additive particles in the mixed powder is greater than 0% by mass and 30% by mass or less, preferably 5% by mass or more and 25% by mass or less. 1% by mass or less. The mixing method is not particularly limited. For example, mechanical alloying method, vibration ball mill, planetary ball mill, mechanofusion, coprecipitation method, chemical vapor deposition method (CVD method), physical vapor deposition method (PVD method), plating Any of the method, sputtering method, vapor deposition method or sol-gel method can be used. The above steps S1a to S3a are the step of producing the mixed powder (step S1).

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

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

  Next, the molded body obtained by pressure molding is heat-treated at a temperature of 200 ° C. or higher and lower than the thermal decomposition temperature of the insulating coatings 20a and 20b (step S3). The thermal decomposition temperature of the insulating coatings 20a and 20b is 500 ° C., for example, in the case of a phosphoric acid insulating coating. This heat treatment is mainly carried out for the purpose of reducing distortion generated in the molded body during pressure molding.

  At this time, since the strain originally present in the iron particles 10a and the additive particles 10b has already been removed by the heat treatment described above, the amount of strain present in the molded body after pressure molding is relatively small. Further, the distortion generated during the pressure molding does not intricately entangle with the distortion originally present in the iron particles 10a and the additive particles 10b. Furthermore, a new distortion is generated by applying pressure from one direction to the mixed powder accommodated in the mold. For these reasons, despite the heat treatment at a relatively low temperature below the thermal decomposition temperature of the insulating coatings 20a and 20b, the strain present in the molded body can be easily reduced.

  Further, since there is almost no distortion inside the iron particles 10a and the additive particles 10b, the composite magnetic particles 30 are easily deformed during pressure molding. For this reason, as shown in FIG. 1, it is possible to form a molded body without a gap in which a plurality of composite magnetic particles 30 mesh with each other. Thereby, the density of a molded object can be enlarged and a high magnetic permeability can be obtained.

  Further, since the heat treatment for the molded body is performed at a relatively low temperature, the insulating coatings 20a and 20b are not deteriorated. Thereby, even after the heat treatment, each of the insulating coatings 20a and 20b is maintained in a state of covering each of the iron particles 10a and the additive particles 10b. Can be reliably suppressed. More preferably, the molded body obtained by pressure molding is heat-treated at a temperature of 200 ° C. or higher and 300 ° C. or lower. In this case, deterioration of the insulating coatings 20a and 20b can be further suppressed.

  The molded body shown in FIG. 1 is completed by the steps described above. In the present invention, the mixing of the organic substance 40 with the composite magnetic particle 30 is not an essential process, and the pressure forming process that continues with only the composite magnetic particle 30 may be performed without mixing the organic substance 40.

  Further, in the present embodiment, the case where the step of forming the insulating coating 20a on the surface of the iron particles 10a and the step of forming the insulating coating 20b on the additive particles 10b are shown separately. It is not limited to such a case, and after mixing the iron particles 10a and the additive particles 10b, each of the insulating coatings 20a and 20b is simultaneously formed on each of the iron particles 10a and the additive particles 10b. May be. Thereby, a manufacturing process can be simplified.

  In the present embodiment, the method of forming the insulating coating 20a by immersing the iron particles 10a in the aqueous solution in which the components of the insulating coating 20a are dissolved has been described. However, the present invention is limited to such a case. The method for forming the insulating coating on the surface of the iron particles is not limited. Further, in the present embodiment, the case where the insulating coatings 20a and 20b are insulators including an aluminum phosphate compound and a calcium phosphate compound has been described. An insulating coating made of an oxide insulator such as manganese phosphate, zinc phosphate, calcium phosphate, aluminum phosphate, silicon oxide, titanium oxide, aluminum oxide, or zirconium oxide may be formed.

  The soft magnetic material of the present embodiment is a soft magnetic material used for the production of a dust core, and includes an addition of iron particles 10a having an insulating coating 20a formed on the surface and at least one of Sendust or Permalloy. And physical particles 10b. The additive particles 10b are included in a proportion of greater than 0% by mass and not greater than 30% by mass.

  The method for manufacturing a soft magnetic material of the present embodiment includes the following steps. A mixed powder is produced in which the iron particles 10a having the insulating coating 20a formed on the surface and the additive particles 10b made of at least one of Sendust or Permalloy are mixed (step S1). The mixed powder is pressure molded to form a molded body (step S2). The formed body is heat treated (step S3). When preparing the mixed powder (step S1), the additive particles are mixed at a ratio of greater than 0% by mass and equal to or less than 30% by mass.

  According to the soft magnetic material and the manufacturing method thereof of the present embodiment, when an AC magnetic field is applied to the soft magnetic material, the sendust or permalloy contained in the soft magnetic material is easily magnetized, and the magnetized sendust or permalloy is Promotes surrounding iron magnetization. As a result, it is possible to obtain a soft magnetic material having high AC magnetic characteristics that cannot be achieved when made of pure iron. Moreover, the fall of the saturation magnetic flux density Bs by Sendust or Permalloy can be suppressed because the quantity of Sendust or Permalloy shall be 30 mass% or less. Furthermore, the fall of the moldability by Sendust or a permalloy can be suppressed because the quantity of Sendust or a permalloy shall be 30 mass% or less. Therefore, the moldability of the soft magnetic material can be improved.

  In the soft magnetic material of the present embodiment, additive particles 10b are included in a proportion of 5% by mass or more and 25% by mass or less.

  In the method for producing a soft magnetic material of the present embodiment, additive particles 10b are mixed at a ratio of 5% by mass or more and 25% by mass or less when a mixed powder is produced (step S1).

  Thereby, the AC magnetic characteristics of the soft magnetic material can be further improved.

  In the soft magnetic material of the present embodiment, a thermoplastic resin as the organic substance 40 is further included in a proportion of 0.01% by mass or more and 0.1% by mass or less.

  In the soft magnetic material of the present invention, when the mixed powder is produced (step S1), the thermoplastic resin as the organic substance 40 is further mixed at a ratio of 0.01% by mass or more and 0.1% by mass or less.

  As a result, the thermoplastic resin is interposed between the composite magnetic particles 30a and the composite magnetic particles 30b. By setting the ratio of the thermoplastic resin to 0.01% by mass or more, the thermoplastic resin bends between the composite magnetic particle 30a and the composite magnetic particle 30b in response to the stress at the time of pressure molding, and thus the composite magnetic particle 30a. The composite magnetic particles 30b function as a lubricant. Moreover, the insulation between the iron particles 10a can be improved. On the other hand, by setting the ratio of the thermoplastic resin to 0.1% by mass or less, the density of the magnetic part of the soft magnetic material can be increased, so that the AC magnetic characteristics can be kept high.

  In the method for producing a soft magnetic material of the present embodiment, a pressure of 980 MPa or more is applied to the mixed powder when forming a molded body (step S2).

  Thereby, since a soft magnetic material can be densified, saturation magnetic flux density Bs can be improved and an alternating current magnetic characteristic can be improved.

  By producing a dust core using the soft magnetic material of the present invention, a dust core having a saturation magnetic flux density of 1.5 T or more can be obtained.

  The method for producing a soft magnetic material according to the present invention is, for example, for producing products such as dust cores, choke coils, switching power supply elements, magnetic heads, various motor parts, automobile solenoids, various magnetic sensors, and various electromagnetic valves. Can be used.

  Examples of the present invention will be described below.

Example 1
In this example, the ratio of the additive particles made of Sendust was changed in the range of 0% by mass to 50% by mass, and the change in AC magnetic characteristics was examined. Specifically, DAPMSA10 (manufactured by Daido Steel Co., Ltd.), a gas atomized sendust powder, was heat-treated at 700 ° C. for 1 hour in a nitrogen atmosphere to produce additive particles. Further, Somaloy (manufactured by Hennegas) was used as composite magnetic particles made of pure iron. Using these two particles, a soft magnetic material was produced in the same manner as in the above embodiment, and a dust core was produced using this soft magnetic material. About the obtained powder magnetic core, using a BH curve tracer, coercive force Hc, magnetic flux density B100 (magnetic flux density when an external magnetic field of 100 Oe (≈8.0 × 10 ⁶ A / m) is applied), and saturation magnetic flux The density Bs was measured. For the coercive force Hc, a theoretical coercive force Hc was calculated, and a reduction rate of the coercive force Hc with respect to the theoretical value was calculated.

  The theoretical coercive force Hc was calculated by the following method. The values of A and B were calculated with the coercive force Hc of Somaloy of 100% by mass as A and the coercive force Hc when 50% by mass of Somaloy and 50% by mass of Sendust were mixed as (0.5A + 0.5B). Using the values of A and B, the theoretical coercive force Hc was calculated from the equation Hc = A (1-x) + Bx (x: mass ratio of Sendust). The results are shown in Table 1, FIG. 3 and FIG.

  As shown in Table 1, FIG. 3, and FIG. 4, when the sendust mixing ratio is greater than 0% by mass and 30% by mass or less, the rate of decrease of the coercive force Hc with respect to the theoretical value is greater than 0%. In particular, when the sendust mixing ratio is 5% by mass or more and 25% by mass or less, the decrease rate of the coercive force Hc with respect to the theoretical value is increased by 4% or more. Thus, it can be seen that when the sendust mixing ratio is greater than 0% by mass and 30% by mass or less, particularly when the Sendust mixing ratio is 5% by mass or more and 25% by mass or less, the AC magnetic characteristics are improved. When the sendust mixing ratio is greater than 0% by mass and not greater than 30% by mass, the saturation magnetic flux density Bs is 1.5T or more, and the magnetic flux density B100 is 1.3T or more. I understand that.

(Example 2)
In this example, the ratio of polyphenylene sulfide (hereinafter referred to as PPS) was changed in the range of 0% by mass to 0.6% by mass, and the change in AC magnetic characteristics was examined. Specifically, about 20% by mass of additive particles prepared in substantially the same manner as in Example 1, about 80% by mass of Somaloy, and 0% by mass to 0.6% by mass of PPS are mixed. A soft magnetic material was produced. And the powder magnetic core was produced using this soft-magnetic material. About the obtained powder magnetic core, coercive force Hc, magnetic flux density B100, saturation magnetic flux density Bs, and iron loss were measured using the BH curve tracer. The iron loss was measured by setting the frequency of the applied external magnetic field to 1 kHz and the output to 10 kG (= 1T). The results are shown in Table 2, FIG. 5 and FIG.

  As shown in Table 2, FIG. 5 and FIG. 6, when the mixing ratio of PPS is 0.01% by mass or more and 0.1% by mass or less, the iron loss is a low value of about 150 W / kg or less. I understand that. It can also be seen that when the PPS mixing ratio is 0.1 mass% or less, the magnetic flux density B100 is a high value of about 1.34 T or more. From the above results, it is possible to improve the insulation between the iron particles by setting the PPS ratio to 0.01% by mass or more, and by setting the PPS ratio to 0.1% by mass or less, the AC magnetism It can be seen that the characteristics can be kept high.

(Example 3)
In this embodiment, the pressure applied to the mixed powder in forming the shaped bodies varied between 7~13t / cm ² (686~1275MPa), investigating changes in the AC magnetic properties of the resulting dust core. Specifically, about 20% by mass of additive particles prepared in substantially the same manner as in Example 1, about 80% by mass of Somaloy, and 0.1% by mass of PPS are mixed to produce a mixed powder. did. The mixed powder was compacted at a pressure of 7 to 13 t / cm ² and then heat treated at a temperature of 400 ° C. for 1 hour. About the obtained powder magnetic core, coercive force Hc, magnetic flux density B100, saturation magnetic flux density Bs, and iron loss were measured using the BH curve tracer. The iron loss was measured by setting the frequency of the applied external magnetic field to 1 kHz and the output to 10 kG (= 1T). The results are shown in Table 3, FIG. 7 and FIG.

As shown in Table 3, FIG. 7 and FIG. 8, when the pressure is 10 t / cm ² (980 MPa) or more, the saturation magnetic flux density Bs is 1.7 (T) or more, which is dramatically improved. Moreover, the value of the coercive force Hc is also decreased. Furthermore, when the pressure is 10 t / cm ² or more, the iron loss is a low value of 148 W / kg or less. From the above results, it can be seen that the AC magnetic characteristics can be improved by applying a pressure of 10 t / cm ² (980 MPa) or more to the mixed powder when forming the compact.

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

It is a schematic diagram which expands and shows the molded object produced by the manufacturing method of the soft-magnetic material in one embodiment of this invention. It is process drawing which shows the manufacturing method of the soft-magnetic material in one embodiment of this invention. It is a figure which shows the relationship between the mixture ratio of Sendust and the coercive force Hc in Example 1 of this invention. It is a figure which shows the relationship between the mixture ratio of Sendust in Example 1 of this invention, and the fall rate of the coercive force Hc with respect to a theoretical value. It is a figure which shows the relationship between the mixing ratio of PPS and the iron loss in Example 2 of this invention. It is a figure which shows the relationship between the mixing ratio of PPS in Example 2 of this invention, and magnetic flux density B100. It is a figure which shows the relationship between the saturation magnetic flux density Bs and the iron loss in Example 3 of this invention. It is a figure which shows the relationship between the press pressure and the iron loss in Example 3 of this invention.

Explanation of symbols

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

Claims (6)

A soft magnetic material used for producing a dust core,
Including iron particles having an insulating coating formed on the surface and additive particles comprising at least one of Sendust or Permalloy, the additive particles being included in a proportion of greater than 0% by mass and 30% by mass or less,
The insulating coating is seen containing a phosphoric acid aluminum compound and a calcium phosphate compound,
A soft magnetic material , further comprising a thermoplastic resin in a proportion of 0.01% by mass to 0.1% by mass .   2. The soft magnetic material according to claim 1, wherein the additive particles are contained in a proportion of 5% by mass or more and 25% by mass or less. A dust core produced using the soft magnetic material according to claim 1 or 2, characterized in that the saturation magnetic flux density is more than 1.5T, dust core. A step of producing a mixed powder in which iron particles having an insulating coating formed on the surface and additive particles made of at least one of Sendust and Permalloy are mixed, the insulating coating comprising an aluminum phosphate compound and a calcium phosphate compound And further,
A step of pressure-molding the mixed powder to form a molded body;
And a step of heat-treating the molded body,
In the step of preparing the mixed powder, the additive particles are mixed at a ratio of greater than 0% by mass and 30% by mass ,
In the step of preparing the mixed powder, a thermoplastic resin is further mixed at a ratio of 0.01% by mass or more and 0.1% by mass or less . 5. The method for producing a soft magnetic material according to claim 4 , wherein in the step of preparing the mixed powder, the additive particles are mixed at a ratio of 5% by mass or more and 25% by mass or less. 6. The method for producing a soft magnetic material according to claim 4 , wherein a pressure of 980 MPa or more is applied to the mixed powder in the step of forming the molded body.

Images