JP2010153638A - Composite soft magnetic material, method for manufacturing composite soft magnetic material, and electromagnetic circuit component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust core for obtaining a high saturation magnetic flux density and suppressing iron loss small, a method for manufacturing the same, and an electromagnetic circuit component provided with the dust core. <P>SOLUTION: The dust core 1 consists of Fe-3Si alloy particle phases 2, and pure iron particle phases 3 interposed in grain boundaries 2a each of which is surrounded by at least three or more Fe-3Si alloy particle phases 2. In the Fe-3Si alloy particle phases 2, a mean particle diameter is set to 100 to 145 μm, and the content of the pure iron particle phases 3 to the entire quantity of the dust core is set to 3 mass% or more and less than 10 mass%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a composite soft magnetic material used as a core material of various electromagnetic circuit components such as a motor, an actuator, a reactor, a transformer, a choke core, and a magnetic sensor core.

Core materials used for electromagnetic circuit components such as motors, actuators, reactors, and the like are required to have high saturation magnetic flux density and low energy loss (iron loss).
Here, iron loss is energy loss expressed as the sum of hysteresis loss and eddy current loss. Of this, hysteresis loss is energy loss caused by energy required to change the magnetic flux density of the core material. The eddy current loss is an energy loss caused by an eddy current flowing in the core material. In order to reduce such iron loss, it is necessary to increase the magnetic permeability μ, the saturation magnetic flux density Bs, and the electrical resistivity ρ of the core material, and to decrease the coercive force Hc.

Specifically, as the core material of such an electromagnetic circuit component, three types of materials are roughly used according to the operating frequency.
For example, silicon steel plates, amorphous soft magnetic ribbons, microcrystalline soft magnetic strips, etc. are mainly used as core materials used in the region of several tens of kHz or less. These core materials are mainly composed of iron, and have the advantage that the saturation magnetic flux density Bs and the relative permeability μr are large. However, among these, the silicon steel sheet has a disadvantage that the iron loss in the high frequency region is large, and the core shape of the amorphous soft magnetic ribbon, the microcrystalline soft magnetic ribbon and the silicon steel plate is the wound core shape. In addition, there is a drawback that it is difficult to form into various shapes like ferrite described later.

 For core materials used in the region of several tens of kHz or more, ferrites typified by Mn—Zn and Ni—Zn are widely used. Since the core material made of these ferrites has a small iron loss in a high frequency region and is relatively easy to mold, it has the feature that various shapes can be mass-produced. However, since the saturation magnetic flux density Bs is lower than that of the above-described silicon steel plate, amorphous soft magnetic ribbon, and microcrystalline soft magnetic ribbon, there is a disadvantage that the magnetic core cross-sectional area becomes large when trying to avoid magnetic saturation.

A dust core is used for the core material used in the region of several kHz to several hundred kHz. A dust core is obtained by insulating the surface of the magnetic powder and then compacting it. The magnetic powder is insulated so that it has a high electrical resistivity ρ and eddy current loss. It can be suppressed.
As such a dust core, one using pure iron particles subjected to insulation treatment as magnetic particles is conventionally known. However, pure iron has magnetic anisotropy and a small permeability μ. Therefore, the dust core using pure iron particles has a drawback that hysteresis loss is large and iron loss cannot be reduced sufficiently.

  Therefore, for example, by using alloy particles such as an Fe—Si alloy and an Fe—Al alloy that have a larger magnetic permeability μ and electric resistivity ρ and a smaller coercive force Hc than that of pure iron, compaction is achieved. It is conceivable to reduce the iron loss of the magnetic core. Examples of the dust core using such alloy particles include those described in Patent Document 1 and Patent Document 2.

 Among these, Patent Document 1 includes first composite magnetic particles in which alloy particles made of Fe—Si alloy, Fe—Al alloy or the like are coated with an insulating coating, and highly compressible soft magnetic particles made of these alloys. A dust core composed of second composite magnetic particles coated with an insulating coating is disclosed. Here, the first composite magnetic particles are the main component of the dust core, and the average particle size of the alloy particles is 3 to 300 μm. In addition, the second composite magnetic particles have an average particle size of not more than the average particle size of the alloy particles constituting the first composite magnetic particles, and are added in the range of 15 to 35% by mass.

Patent Document 2 discloses a dust core composed of Fe—Si based alloy powder having a Si content of 5 to 8 mass% and pure Fe powder. Here, it is described that the average particle diameter of the Fe—Si based alloy powder is preferably 50 to 100 μm, the average particle diameter of the pure Fe powder is 10 to 50 μm, and the content of the pure Fe powder is 10 to 55%. ing.
JP 2006-135164 A JP 2008-192897 A

  However, as a result of investigations by the present inventors, these conventional powder magnetic cores have a molding density and an attempt to reduce iron loss by controlling the blending ratio of particles, the composition of alloy particles, the average particle diameter, and the like. When the saturation magnetic flux density is reduced and these characteristics are improved, the iron loss tends to increase, and it is difficult to simultaneously improve the saturation magnetic flux density and reduce the iron loss.

  The present invention has been made in view of the above-described problems, and provides a dust core capable of obtaining a high saturation magnetic flux density and suppressing iron loss to be small, a manufacturing method thereof, and an electromagnetic including such a dust core. The object is to provide circuit components.

 In order to solve the above problems, the present inventors have conducted intensive studies, and as a result, existed in a grain boundary surrounded by a plurality of Fe-3Si alloy particle phases and at least three or more Fe-3Si alloy particle phases. The powder magnetic core has a high saturation magnetic flux density and a small iron loss by defining the average particle size of the Fe-3Si alloy particle phase and the ratio of the pure iron particle phase. It came to the knowledge that it was obtained. The present invention has been proposed based on such knowledge and has the following configuration.

(1) The present invention is a composite soft magnetic material in which Fe-3Si alloy particles and pure iron particles are consolidated and fired, and includes a plurality of Fe-3Si alloy particle phases and at least three Fe-3Si particles. A plurality of pure iron particle phases existing at grain boundaries surrounded by the alloy particle phase, the Fe-3Si alloy particle phase has an average particle size of 100 to 145 μm, and the dust core of the pure iron particle phase The content ratio with respect to the total amount is 3% by mass or more and less than 10% by mass.

(2) The present invention is characterized in that an average particle size of the pure iron particle phase is 20 μm or more and 50 μm or less.
By setting the average particle diameter of the pure iron particle phase in such a range, the iron loss can be further reduced and the saturation magnetic flux density Bs can be further increased.

(3) In the present invention, at least one of a grain boundary between the Fe-3Si alloy particle phases, a grain boundary between the pure iron particles, and a grain boundary between the Fe-Si based alloy particle and the pure iron particle, It has an insulating layer.
(4) In the method for producing a composite soft magnetic material of the present invention, Fe-3Si alloy particles having an average particle diameter of 100 to 145 μm and pure iron particles are contained, and the content of the pure iron particles is 3% by mass or more and 10% by mass. The first step of obtaining mixed particles by mixing so as to be less than%, the second step of obtaining a molded body by press molding the mixed particles, and Fe- A third step of obtaining a composite soft magnetic material having a 3Si alloy particle phase and a plurality of pure iron particle phases present at a grain boundary surrounded by at least three Fe-3Si alloy particle phases. Features.
(5) The method for producing a composite soft magnetic material of the present invention is characterized in that the surface of the pure iron particles is smoothed and mixed so as to be 3% by mass or more and less than 10% by mass.
(6) In the method for producing a composite soft magnetic material of the present invention, the bulk density (AD) of the pure iron particles is 0.09 to 0.25 Mg / m ³ higher than that of the pure iron particles before smoothing. A method for producing a composite soft magnetic material according to claim 5 or 6.
(7) The method for producing a composite soft magnetic material according to the present invention includes a step of forming an insulating film on at least one of the Fe-3Si alloy particles and the pure iron particles.
(8) An electromagnetic circuit component according to the present invention includes the composite soft magnetic material according to any one of (1) to (3).

As described above, according to the present invention, since the Fe-3Si alloy particle phase is used as the main component of the powder magnetic core, the coercive force Hc is low, the electrical resistivity ρ is high, and the iron loss is suppressed to a low level. A composite soft magnetic material such as a dust core can be obtained.
Further, since a pure iron particle phase is present at a grain boundary surrounded by at least three Fe-3Si alloy particle phases, and the content of the pure iron particle phase is within a predetermined range, the homology of Fe-3Si alloy particles It is possible to reliably fill the gaps between the two with a magnetic material (pure iron particle phase). For this reason, the composite soft magnetic material of the present invention can obtain a high saturation magnetic flux density Bs.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a composite soft magnetic material, a manufacturing method thereof, and an electromagnetic circuit component of the present invention will be described based on preferred embodiments shown in the accompanying drawings.
<Composite soft magnetic material>
First, a dust core will be described as a composite soft magnetic material according to the present invention.
FIG. 1 is a schematic cross-sectional view showing an embodiment of a powder magnetic core as a composite soft magnetic material according to the present invention, and FIG. 1 is a 1000 times enlarged view of a sample obtained in an example described later.
A composite soft magnetic material (dust core) 1 shown in FIG. 1 exists at a grain boundary 2 a surrounded by a plurality of Fe-3Si alloy particle phases 2 and at least three Fe-3Si alloy particle phases 2. A plurality of pure iron particle phases 3.
Each Fe-3Si alloy particle phase 2 has a granular shape and is integrated by adhering adjacent Fe-3Si alloy particle phases 2 to each other.

 The average particle diameter of the Fe-3Si alloy particle phase 2 used in the present invention is in the range of 100 to 145 μm. When the average particle diameter of the Fe-3Si alloy particle phase 2 is smaller than 100 μm, the saturation magnetic flux density Bs of the dust core 1 is decreased. Moreover, when the average particle diameter of the Fe-3Si alloy particle phase 2 exceeds 145 μm, intragranular eddy current loss increases. Furthermore, the more preferable range of the average particle diameter of the Fe-3Si alloy particle phase 2 is 110 to 140 μm. When the average particle diameter of the Fe-3Si alloy particle phase 2 is within such a range, the intragranular eddy current loss can be further reduced, and the saturation magnetic flux density Bs of the dust core 1 can be further increased. Can do. In the present specification, “average particle diameter” indicates D50.

Each pure iron particle phase 3 is a particulate phase in which the iron content exceeds 99.5% by mass. These pure iron particle phases 3 exist at the grain boundaries 2 a surrounded by three or more Fe-3Si alloy particle phases 2. Thereby, the following effects can be obtained.
That is, since Fe-Si based alloy particles have poor compressibility, when a compacted body is produced by pressure forming and firing alone, the particle shape of the Fe-Si based alloy particles remains in the product as it is. Easy to hold. In this case, particularly when there are too many iron particles, the iron particles have better compressibility than the alloy particles, and the iron particles have a higher saturation magnetic flux density than the alloy particles. It is advantageous in terms of saturation magnetic flux density, but due to the low specific resistance that is also a disadvantage of iron particles, the overall specific resistance suddenly decreases, and the amount of eddy current loss increases, There is a problem that causes an increase in total iron loss as the dust core 1.
On the other hand, as shown in FIG. 1, when an appropriate amount of pure iron particle phase 3 is present in the grain boundary 2a surrounded by three or more Fe-3Si alloy particle phases 2, the Fe-3Si alloy Since the gap between the particle phases 2 is filled with a magnetic material (pure iron particle phase 3), a higher saturation magnetic flux density Bs can be obtained as compared with a compacted body constituted only by the Fe-3Si alloy particle phase. .
Here, it is preferable that the pure iron particle phase 3 does not substantially exist in the grain boundary 2b sandwiched only between the two Fe-3Si alloy particle phases 2. By setting it as the structure | tissue in which the pure iron particle phase 3 does not exist substantially in the grain boundary 2b, the fall of the saturation magnetic flux density of the dust core 1 can be prevented.

  The average particle diameter of the pure iron particle phase 3 is preferably 20 μm or more and 50 μm or less. When the average particle diameter of the pure iron particle phase 3 is smaller than 20 μm, the coercive force Hc of the dust core 1 is increased and the iron loss is increased. On the other hand, when the average particle diameter of the pure iron particle phase 3 exceeds 50 μm, as will be described later, when the mixed particles composed of Fe—Si based alloy particles and pure iron particles are formed by pressure, the forming density thereof becomes low. As a result, the saturation magnetic flux density Bs of the dust core 1 obtained by firing this pressure-molded body is lowered.

Moreover, in this invention, the content rate of the pure iron particle phase 3 with respect to the dust core 1 whole quantity shall be 3 mass% or more and less than 10 mass%. When the content of the pure iron particle phase 3 is smaller than 3% by mass, the effect of adding the pure iron particle phase 3, that is, the effect of improving the saturation magnetic flux density Bs of the dust core 1 cannot be sufficiently obtained. Further, when the content of the pure iron particle phase 3 is 10% by mass or more, excessive pure iron particles that cannot be accommodated in the grain boundary 2a surrounded by the three or more Fe-3Si alloy particle phases 2 are generated. As a result, a gap 4 is generated in the grain boundary 2b sandwiched between the two Fe-3Si alloy particle phases 2 (see FIG. 2). For this reason, in the range where the content of the pure iron particle phase 3 is less than 10% by mass, even if the content of the pure iron particle phase 3 is increased, the iron loss hardly changes and is kept at a relatively low value. When the content of the pure iron particle phase 3 is 10% by mass or more, the iron loss of the dust core 1 increases rapidly depending on the increase in the content.
Here, the iron loss is the sum of hysteresis loss and eddy current loss. The hysteresis loss depends on the size of the iron particle crystal, and the larger the crystal, the smaller the hysteresis loss. Therefore, when the content of iron particles increases, it tends to increase in proportion. Eddy current loss depends on electrical resistance, and it is considered that eddy current increases in a conductor when the resistance between powders is low, leading to a rapid increase. From this, when iron particles with low electrical resistance are contained in Fe-3Si with high electrical resistance, each iron particle is coated with an insulating film, but the insulating film is easily broken by high pressure molding, When iron particles having a broken coating are brought into contact with each other, the eddy current is greatly increased, and as a result, it seems that the iron loss is rapidly increased. Therefore, the iron particles filled in the gap surrounded by the Fe-3Si alloy particle phase 2 are not greatly deformed by molding, but the iron particles that could not be accommodated in the gap were greatly deformed. There are many cases where the film is torn, and the presence of iron particles that have not been accommodated in the gap and the insulating coating has been broken is considered to cause a decrease in specific resistance.

 Therefore, the grain boundary between each Fe-3Si alloy particle phase 2, the grain boundary between each pure iron particle phase 3, and the grain boundary between each Fe-3Si alloy particle phase 2 and each pure iron particle phase 3 are: Each is preferably provided with an insulating layer. Thereby, the electrical resistivity ρ of the dust core 1 is increased, and the generation of eddy current is suppressed. As a result, iron loss due to eddy current loss of the dust core 1 can be reduced.

The constituent material of the insulating layer is not particularly limited. For example, an oxide insulating material such as iron phosphate, aluminum phosphate, manganese phosphate, zinc phosphate, calcium phosphate, silicon oxide, titanium oxide, aluminum oxide or zirconium oxide, Examples thereof include thermoplastic resins such as thermoplastic polyamide, thermoplastic polyimide, thermoplastic polyamideimide, polyethylene, polyphenylene sulfide, polyamideimide, polyethersulfone, polyetherimide, or polyetherketone, and one or two of these A combination of the above can be used.
Among these, when the insulating layer contains a thermoplastic resin, the thermoplastic resin functions as a bonding material for bonding particles, and the powder magnetic core 1 having excellent mechanical strength can be obtained.

The powder magnetic core 1 as described above is composed mainly of the Fe-3Si alloy particle phase 2 in which the Si content and the average particle diameter are in a predetermined range, so that the coercive force Hc is small and the electric resistance is low. The rate ρ is large, and the iron loss can be suppressed small.
Moreover, the pure iron particle phase 3 exists in the grain boundary 2a surrounded by at least three or more Fe-3Si alloy particle phases 2, and the content rate of this pure iron particle phase 3 is made into the predetermined range. Thus, the gap (grain boundary 2a) between the Fe-3Si alloy particle phases 2 is reliably filled with the magnetic material (pure iron particle layer 3), and a high saturation magnetic flux density Bs can be obtained.

<Method of manufacturing a dust core>
Next, the manufacturing method of the dust core of the present invention will be described by taking as an example the case of manufacturing the dust core shown in FIG. FIG. 3 is a process diagram showing an example of a method of manufacturing a dust core according to the present invention in the order of steps. Hereinafter, each step will be described.

[1] Pretreatment process of Fe-Si based alloy particles First, Fe-Si based alloy particles are prepared (step S11). These Fe—Si based alloy particles finally become the Fe-3Si alloy particle phase 2 of the dust core 1.

 Next, the Fe—Si alloy particles are heat-treated at a temperature of 800 to 1400 ° C. in a reducing atmosphere (step S12). The purpose of the heat treatment performed here is to reduce the coercive force (hysteresis loss) by reducing strain.

 Next, the Fe—Si based alloy particles are classified using, for example, a stainless sieve so that the average particle diameter is 100 to 145 μm (step S13).

Next, the Fe—Si based alloy particles are covered with an insulating coating (step S14).
The insulating coating is formed, for example, by immersing Fe—Si-based alloy particles in a liquid material containing the constituent material of the insulating layer described above or a precursor thereof, and then performing a post-treatment as necessary. can do.

[2] Pure Iron Particle Pretreatment Step First, pure iron particles are prepared (step S21). The pure iron particles finally become the pure iron particle phase 3 of the dust core 1. The pure iron particles are classified using, for example, a stainless sieve so that the average particle diameter is 20 to 50 μm (step S22).

Next, pure iron particles are covered with an insulating coating (step S23).
The coating method of the insulating coating and the thickness of the insulating coating are the same as in the case of Fe—Si based alloy particles.
In this example, the step of coating the Fe—Si-based alloy particles with the insulating coating and the step of coating the pure iron particles with the insulating coating are performed in separate steps, but the Fe before forming the insulating coating is performed. -After mixing Si-type alloy particles and pure iron particles at a predetermined mixing ratio, these particles may be subjected to a treatment for simultaneously forming an insulating coating.

In the present invention, the surface of the pure iron particles may be smoothed. As for this surface smoothing, only pure iron powder is time-varying with mechanofusion, and the surface of pure iron powder is smoothed by compressing and shearing at high rotation, and pure iron particles with few corners can be obtained. . Further, when the pure iron particles are smoothed, the fluidity of the pure iron powder particles can be improved at the same time.
By this treatment, the density after consolidation can be improved and the characteristics can be improved.

[3] Molding / firing step of Fe—Si based alloy particles and pure iron particles Next, the Fe—Si based alloy particles pretreated in the above steps [1] and [2] are mixed with pure iron particles. Then, mixed particles are obtained (step S31, step S32). The mixing ratio of the Fe—Si alloy particles and the pure iron particles is such that the content of the pure iron particles with respect to the total amount of the mixed particles is 3% by mass or more and less than 10% by mass. The mixing method is not particularly limited, and for example, a mechanical alloying method, a vibration ball mill method, a planetary ball mill method, or the like can be used.

Next, the obtained mixed particles are put into a mold and press-molded in the atmosphere to obtain a molded body (step 33).
Here, the pressure of pressure molding is about 785 MPa, and the temperature is about 130 to 160 ° C. By performing pressure molding under such conditions, a molded body having a high density can be obtained.

Next, the compact is fired (heat treated) to obtain a dust core (step 34).
The heat treatment temperature is lower than the lower one of the thermal decomposition temperature of the insulating coating formed on the Fe-Si based alloy particles or the thermal decomposition temperature of the insulating coating formed on the pure iron particles, and 300 ° C or higher. Set to temperature.
By this heat treatment, as shown in FIG. 1, the pressure at which the pure iron particle phase 3 exists in the grain boundary 2a surrounded by the plurality of Fe-3Si alloy particle phases 2 and the three or more Fe-3Si alloy particle phases 2 is obtained. A powder magnetic core 1 is obtained.
The dust core 1 manufactured as described above is composed mainly of the Fe-3Si alloy particle phase 2 in which the Si content and the average particle diameter are in a predetermined range, so that the coercive force Hc is Small, high electrical resistivity ρ, and low iron loss.
Moreover, the pure iron particle phase 3 exists in the grain boundary 2a surrounded by at least three or more Fe-3Si alloy particle phases 2, and the content rate of this pure iron particle phase 3 is made into the predetermined range. Thus, the gap (grain boundary 2a) between the Fe-3Si alloy particle phases 2 is reliably filled with the magnetic material (pure iron particle layer 3), and a high saturation magnetic flux density Bs can be obtained.

<Electromagnetic circuit components>
Next, an electromagnetic circuit component to which a dust core as a composite soft magnetic material according to the present invention is applied will be described by taking a reactor as an example.
FIG. 4 is a perspective view showing a reactor to which the dust core of the present invention is applied, and FIG. 5 is a perspective view showing a reactor core provided in the reactor of FIG.
A reactor 10 shown in FIG. 4 includes a reactor core 11 and two coils 12 wound around the reactor core 11.

As shown in FIG. 5, the reactor core 11 is disposed with a space between a pair of U-shaped cores 11a and 11b having a U shape in a plan view and the pair of U-shaped cores 11a and 11b. A plurality of rectangular cores (I-type cores) 11c, a gap plate 14 interposed between the U-type cores 11a and 11b and the I-type core 11c, and between the I-type cores 11c and 11c, and a gap plate It has the adhesive bond layer 15 which adhere | attaches 14, and has comprised the horizontal ellipse shape as a whole. In the reactor 11, when a current is passed through the coil 12, a magnetic circuit is formed in the annular direction.
As shown in FIG. 4, each coil 12 is composed of a conducting wire wound many times, and is wound around a straight section in the longitudinal direction of the reactor core 11.
In the reactor 10, the reactor core 11 is constituted by the dust core of the present invention.

 In such a reactor 10, the reactor core 11 has a low coercive force Hc, a high electrical resistivity ρ, a small iron loss, and a high saturation magnetic flux density Bs. For this reason, for example, even when a large current is supplied to the coil 12, the reactor core 11 is not easily magnetically saturated, the loss of electric energy is suppressed small, and high performance as the reactor 10 can be obtained.

 In addition, in the said embodiment, each process of the manufacturing method of each part which comprises a powder magnetic core and an electromagnetic circuit component, and a powder magnetic core is an example, Comprising: It can change suitably in the range which does not deviate from the scope of the present invention.

  Next, specific examples of the present invention will be described. In addition, this invention is not restrict | limited by this Example.

<Examination of the addition amount of pure iron particles when using alloy particles having an average particle size of 101 μm and pure iron particles having an average particle size of 48 μm>
(Example 1-1)
First, Fe-3% Si alloy particles were prepared and heat-treated at 1000 ° C. for 3 hours in a hydrogen atmosphere. Next, the heat-treated alloy particles were classified using a stainless steel sieve, and alloy particles having an average particle diameter of 101 μm were collected.
The alloy particles were then coated with silicon resin by dipping in a 1.0% resin solution and drying.

Moreover, pure iron particles (trade name Somaloy 110i manufactured by Höganäs) with a phosphoric acid coating were prepared.
And this pure iron particle was classified using the stainless steel sieve, and the pure iron particles whose average particle diameter is 48 micrometers were collect | recovered. Next, the pure iron particles were dipped in a 1% resin solution and dried to coat the silicon resin.
Next, alloy particles and pure iron particles are mixed so that the content of pure iron particles is 3% by mass to prepare mixed particles, and the mixed particles are pressed to obtain a compact. It was.
The conditions for pressure molding are a temperature of 150 ° C. and a pressure of 785 MPa.
Next, the compact was fired at a temperature of 800 ° C. for 1 hour under vacuum to obtain a fired body (a dust core).
A dust core containing 3% by mass of pure iron particles was manufactured by the above process.

(Examples 1-2 to 1-4)
A dust core was manufactured in the same manner as in Example 1-1 except that the content of pure iron particles was changed as shown in Table 1.

(Comparative Example 1-1)
A powder magnetic core to which pure iron particles are not added by pressure-forming and firing alloy particles pretreated in the same manner as in Example 1-1 under the same conditions as in Example 1-1. Manufactured.
(Comparative Examples 1-2 to 1-5)
A dust core was manufactured in the same manner as in Example 1-1 except that the content of pure iron particles was changed as shown in Table 1.

[Evaluation]
About the dust cores manufactured in each of the examples and comparative examples as described above, the density in water, DC characteristics (coercive force Hc, maximum permeability μmax, saturation magnetic flux density Bs), and AC characteristics (iron loss Pcm, Hysteresis loss Phm and eddy current loss Pem) were measured.
Here, the direct current characteristics were measured under the condition of the maximum magnetic field Hm: 2 kA / m or 10 kA / m using a BH tracer (DC magnetization measuring device B integration unit TYPE 3257 manufactured by Yokogawa).
In addition, the AC characteristics were measured using a BH analyzer (SY-8232, manufactured by Iwatatsu Measurement Co., Ltd.) under the conditions of saturation magnetic flux density Bm: 0.1 T and frequency f: 10 kHz.

 The measurement results are shown in Table 1 together with the amount of pure iron particles added to each dust core. FIG. 6 shows the relationship between the amount of pure iron particles added and the density in water, FIG. 7 shows the relationship between the amount of pure iron particles added and the saturation magnetic flux density Bs, and the relationship between the amount of pure iron particles added and the iron loss Pcm. FIG. 8 shows the relationship between the saturation magnetic flux density Bs and the iron loss Pcm, respectively. Moreover, the schematic diagram of the structure | tissue photograph of the sample of 5 mass% of pure iron particles shown in Table 1 as Example 1-2 is shown in FIG. 1, and the sample of 10 mass% of pure iron particles shown in Table 1 as Comparative Example 1-2 A schematic diagram of the structure photograph is shown in FIG.

From the comparison between FIG. 1 and FIG. 2, the metal structure of the sample in which the mixing ratio of the pure iron particles is a preferable amount is such that the pure iron particles are densely arranged at the grain boundaries formed by three or more Fe-3Si particles. However, when the amount of pure iron particles added is excessive, not only the grain boundary formed by three or more Fe-3Si particles but also the grain boundary between two Fe-3Si particles. It can be seen that a considerable number of pure iron particles have entered and the gap 4 has increased. In such a metal structure, there is a high possibility that the insulating coating on the surface of the pure iron particles existing between the hard Fe-3Si particles is broken, and this is considered to cause an increase in iron loss. .
6 and 7, the underwater density and the saturation magnetic flux density Bs increase as the amount of pure iron particles added increases.
Moreover, from FIG. 8, the iron loss Pcm hardly changes in the range where the amount of pure iron particles added is less than 10% by mass, and is maintained at a relatively small value (20 W / kg or less). It can be seen that when the addition amount is 10% by mass or more, it increases rapidly depending on the addition amount.
Furthermore, when FIG. 9 is seen, the iron loss Pcm hardly changes in the range where the saturation magnetic flux density Bs is 1.1 T or less (the amount of pure iron particles added is less than 10% by mass), but exceeds 1.1 T. It is increasing rapidly.

From this, it can be said that in order to improve the saturation magnetic flux density Bs while keeping the iron loss small, it is necessary to make the addition amount of pure iron particles less than 10 mass%. On the other hand, when the addition amount of the pure iron particles is less than 3% by mass, the effect of increasing the saturation magnetic flux density Bs is hardly obtained (see FIG. 7).
From the above, it was found that an appropriate range of the addition amount of the pure iron particles is 3% by mass or more and less than 10% by mass.

<Examination of the addition amount of pure iron particles when using alloy particles having an average particle size of 140 μm and pure iron particles having an average particle size of 38 μm>
(Example 2-1)
When classifying the alloy particles and the pure iron particles, powder compaction was performed in the same manner as in Example 1-1, except that the alloy particles having an average particle diameter of 140 μm and the pure iron particles having an average particle diameter of 38 μm were recovered. A magnetic core was manufactured.
(Examples 2-2 to 2-4)
A dust core was manufactured in the same manner as in Example 2-1 except that the content of pure iron particles was changed as shown in Table 2.

(Comparative Example 2-1)
A powder magnetic core was manufactured by press-molding and firing alloy particles pretreated in the same manner as in Example 2-1 under the same conditions as in Example 2-1.
(Comparative Examples 2-2, 2-3)
A dust core was manufactured in the same manner as in Example 2-1 except that the content of pure iron particles was changed as shown in Table 2.

[Evaluation]
About the dust cores manufactured in each of the examples and comparative examples as described above, the density in water, DC characteristics (coercive force Hc, maximum permeability μmax, saturation magnetic flux density Bs), and AC characteristics (iron loss Pcm, Hysteresis loss Phm and eddy current loss Pem) were measured in the same manner as described above.
The measurement results are shown in Table 2 together with the amount of pure iron particles added to each dust core. FIG. 10 shows the relationship between the amount of pure iron particles added and the density, FIG. 11 shows the relationship between the amount of pure iron particles added and the saturation magnetic flux density Bs, and the relationship between the amount of pure iron particles added and the iron loss Pcm. FIG. 12 shows the relationship between the saturation magnetic flux density Bs and the iron loss Pcm, respectively.

First, referring to FIGS. 10 and 11, the underwater density and the saturation magnetic flux density Bs increase as the amount of pure iron particles added increases.
Further, from FIG. 12, the iron loss Pcm is maintained at a relatively small value (20 W / kg or less), with the addition amount of pure iron particles hardly changing up to 9% by mass, and the addition amount of pure iron particles. It can be seen that when the amount is 10% by mass or more, it rapidly increases depending on the amount of addition.
Furthermore, when FIG. 13 is seen, the iron loss Pcm hardly changes in the range where the saturation magnetic flux density Bs is 1.29 or less (the amount of pure iron particles added is less than 10% by mass), but exceeds 1.3T. It is increasing.

From this, it can be said that in order to improve the saturation magnetic flux density Bs while keeping the iron loss small, it is necessary to make the addition amount of pure iron particles less than 10 mass%. On the other hand, when the addition amount of the pure iron particles is less than 3% by mass, the effect of increasing the saturation magnetic flux density Bs is not obtained so much (see FIG. 11).
From the above, it was found that an appropriate range of the addition amount of the pure iron particles is 3% by mass or more and less than 10% by mass.

<Examination of the addition amount of pure iron particles when using alloy particles having an average particle size of 140 μm and pure iron particles having an average particle size of 26 μm>
(Example 3-1)
When classifying the alloy particles and the pure iron particles, the dust particles were collected in the same manner as in Example 1-1 except that the alloy particles having an average particle size of 140 μm and the pure iron particles having an average particle size of 26 μm were recovered. A magnetic core was manufactured.
(Examples 3-2 to 3-4)
A dust core was produced in the same manner as in Example 3-1, except that the content of pure iron particles was changed as shown in Table 3.

(Comparative Example 3-1)
A powder magnetic core was manufactured by press-molding and firing alloy particles pretreated in the same manner as in Example 3-1, under the same conditions as in Example 2-1.
(Comparative Examples 3-2 and 3-3)
A dust core was manufactured in the same manner as in Example 2-1 except that the content of pure iron particles was changed as shown in Table 3.

[Evaluation]
About the dust cores manufactured in each of the examples and comparative examples as described above, the density in water, DC characteristics (coercive force Hc, maximum permeability μmax, saturation magnetic flux density Bs), and AC characteristics (iron loss Pcm, Hysteresis loss Phm and eddy current loss Pem) were measured in the same manner as described above.
The measurement results are shown in Table 3 together with the amount of pure iron particles added to each dust core. FIG. 14 shows the relationship between the amount of pure iron particles added and the density, FIG. 15 shows the relationship between the amount of pure iron particles added and the saturation magnetic flux density Bs, and FIG. 15 shows the relationship between the amount of pure iron particles added and the iron loss Pcm. FIG. 16 shows the relationship between the saturation magnetic flux density Bs and the iron loss Pcm, respectively.

First, in FIGS. 14 and 15, the underwater density and the saturation magnetic flux density Bs increase as the amount of pure iron particles added increases.
Moreover, from FIG. 16, the iron loss Pcm is maintained at a relatively small value (20 W / kg or less), with the addition amount of pure iron particles hardly changing up to 9% by mass, and the addition amount of pure iron particles. It can be seen that when the amount is 10% by mass or more, it increases depending on the amount of addition.
Furthermore, when FIG. 17 is seen, the iron loss Pcm hardly changes in the range where the saturation magnetic flux density Bs is 1.28 T or less (the amount of pure iron particles added is less than 10% by mass), but exceeds 1.29 T. It is increasing rapidly.

From this, it can be said that in order to improve the saturation magnetic flux density Bs while keeping the iron loss small, it is necessary to make the addition amount of pure iron particles less than 10 mass%. On the other hand, when the addition amount of the pure iron particles is less than 3% by mass, the effect of increasing the saturation magnetic flux density Bs is not obtained so much (see FIG. 15).
From the above, it was found that an appropriate range of the addition amount of the pure iron particles is 3% by mass or more and less than 10% by mass.

(Example 4-1 to Example 4-5)
When classifying the alloy particles, the alloy particles having an average particle size shown in Table 3 are collected, and when the alloy particles and the pure iron particles are mixed, the addition amount of the pure iron particles is set to 7% by mass. A dust core was manufactured in the same manner as in Example 1-1.

<Examination of average particle size of alloy particles>
(Comparative Example 4-1)
A powder magnetic core was produced in the same manner as in Example 4-1, except that the alloy particles having an average particle size shown in Table 3 were collected when classifying the alloy particles.

[Evaluation]
About the dust cores manufactured in each of the examples and comparative examples as described above, the density in water, DC characteristics (coercive force Hc, maximum permeability μmax, saturation magnetic flux density Bs), and AC characteristics (iron loss Pcm, Hysteresis loss Phm and eddy current loss Pem) were measured in the same manner as described above.
The measurement results are shown in Table 4 together with the amount of pure iron particles added to each dust core. FIG. 18 shows the relationship between the addition amount and density of pure iron particles, FIG. 19 shows the relationship between the addition amount of pure iron particles and saturation magnetic flux density Bs, and the relationship between the addition amount of pure iron particles and iron loss Pcm. FIG. 20 shows the relationship between the saturation magnetic flux density Bs and the iron loss Pcm, respectively.

 From FIG. 18, the density in water tends to increase depending on the average particle size until the average particle size of the alloy particles is up to 108 μm, and decrease when the average particle size is larger than that. In addition, as shown in FIG. 19, the saturation magnetic flux density Bs increases greatly depending on the average particle size until the average particle size of the alloy particles reaches 101 μm, but becomes substantially constant when the average particle size exceeds 108 μm. . Furthermore, FIG. 20 shows that the iron loss Pcm hardly changes even when the average particle diameter of the alloy particles increases.

Here, the saturation magnetic flux density Bs of the reactor needs to exceed 1T, and more preferably 1.1T or more. Such a saturation magnetic flux density Bs is obtained when the average particle diameter of the alloy particles is 100 μm or more (see FIG. 19).
This shows that the lower limit of the average particle diameter of the alloy particles is 100 μm, more preferably 110 μm.

<Smoothing test>
Pure iron particles with a phosphoric acid coating (trade name Somaloy 110i manufactured by Höganäs) used in the above examples were prepared. The pure iron particles were subjected to surface smoothing using a mechanofusion apparatus (manufactured by Hosokawa Micron Corporation: model number AMS-30F). The operating conditions of the apparatus were such that the rotational speed was 1500 rpm, the processing time was 2 minutes, 4 minutes, 6 minutes, 8 minutes, and 10 kg of pure iron particles (pure iron powder) were smoothed per batch.
Regarding smoothing of the obtained pure iron powder, the original pure iron particles, pure iron particles after 2 minutes treatment, pure iron particles after 4 minutes treatment, pure iron particles after 6 minutes treatment, pure after 8 minutes treatment FIG. 22 shows a micrograph magnified 1500 times for the iron particles and the pure iron particles after 10 minutes of treatment. Moreover, the result of having measured the bulk density with respect to smoothing time is shown in FIG. From the results shown in FIGS. 22 and 23, the bulk density is improved as the treatment time is increased, and the surface of the pure iron particles can be smoothed. Therefore, the bulk density and the surface density can be adjusted by adjusting the distillation treatment time by the mechanofusion apparatus. It is clear that the smooth state can be controlled.

Next, Fe-3Si alloy particles and pure iron particles having a smooth surface were used, and Fe-3Si alloy particles and pure iron particles were mixed at a mixing ratio of 93: 7. Each particle was dried and baked by immersing the powder in a 0.6% resin solution of Momentive Performance Materials Japan GK (trade name: YR3370). In addition, immersing the powder in the 0.6% solution means that 0.6% by weight of silicon resin was added.
In addition, the mechano-fusion processing of pure iron powder is a condition for smoothing 10 kg of pure iron powder per batch at 1500 rpm for 0 minute (no treatment), 2 minutes, 4 minutes, 6 minutes, 8 minutes, 10 minutes each. Various samples were prepared.

Next, the aforementioned Fe-3Si alloy particles and pure iron particles are mixed so that the content of pure iron particles is 7% by mass to prepare mixed particles, and the mixed particles are warm-formed. A molded body was obtained.
The conditions for warm forming are a temperature of 150 ° C. and a pressure of 785 MPa.
Next, the compact was fired at a temperature of 800 ° C. for 1 hour under vacuum to obtain a fired body (a dust core).
The dust core containing 7 mass% pure iron particles was manufactured by the above process.

About the powder magnetic core manufactured as mentioned above, dimensional density, underwater density, specific resistance, AC characteristics (iron loss Pcm, hysteresis loss Phm, eddy current loss Pem), and DC characteristics (coercive force Hc, maximum) Permeability μmax and saturation magnetic flux density Bs) were measured. The measurement conditions and measurement apparatus in this measurement are the same as those in the previous embodiment.
The above measurement results are shown in Table 5 below, and FIG. 24 shows the relationship between the specific resistance of the dust core obtained and the smoothing time. FIG. 25 shows the eddy loss and smoothing time of the dust core obtained. FIG. 26 shows the relationship between the coercive force of the obtained dust core and the smoothing time, and FIG. 27 shows the relationship between the iron loss of the obtained dust core and the smoothing time.

From the results shown in Table 5 and FIGS. 23 to 27, when 3 to 10 mass% is added to Fe-3Si alloy particles after pure iron particles are smoothed, the smoothing time increases beyond 4 minutes and the specific resistance is increased. It is clear that the eddy current loss decreases as the smoothing time increases, and the iron loss also decreases slightly. Further, in these results, pure iron particles having a high range of 0.09 to 0.25 Mg / m ³ with respect to the pure iron particles before smoothing are compared with the bulk density (AD) of the pure iron particles. When 3 to 10% by mass is added to the Fe-3Si alloy particles, the specific resistance increases and the loss can be reduced. This is because the surface of the pure iron particles having a large irregular shape as shown in FIG. 22 (A) is smoothed by smoothing the surface of the pure iron particles with a mechanofusion device. Since the compaction is performed, it seems that the resin or other coating layer formed on the particle surface is less likely to be broken than the compaction of pure iron particles having irregular shapes on the surface. When the deformed pure iron particles are pressed together during consolidation, the corners of the deformed pure iron particles are pressed against the resin layer coated on the surface, so that cracks are easily generated, resulting in a decrease in specific resistance. It seems to be. Therefore, it seems that the smoothing effect appears.

  The dust core according to the present invention can be used as an electromagnetic circuit component, for example, as a magnetic core, a motor core, a generator core, a solenoid core, an ignition core, a reactor core, a transformer core, a choke coil core, or a magnetic sensor core. In any case, excellent characteristics can be exhibited.

It is a cross-sectional schematic diagram of the powder magnetic core which concerns on this invention. It is a cross-sectional schematic diagram of the powder magnetic core containing a 10 mass% pure iron particle phase. It is process drawing which shows an example of the manufacturing method of the powder magnetic core of this invention. It is a perspective view which shows the electromagnetic circuit components (reactor) to which the dust core of this invention is applied. It is a perspective view which shows the reactor core with which the reactor shown in FIG. 4 is provided. It is a figure which shows the relationship between the addition amount of a pure iron particle, and a density in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the addition amount of a pure iron particle, and the saturation magnetic flux density Bs in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the addition amount of a pure iron particle, and the iron loss Pcm in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the saturation magnetic flux density Bs and the iron loss Pcm in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the addition amount of a pure iron particle, and a density in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the addition amount of a pure iron particle, and the saturation magnetic flux density Bs in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the addition amount of a pure iron particle, and the iron loss Pcm in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the saturation magnetic flux density Bs and the iron loss Pcm in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the addition amount of a pure iron particle, and a density in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the addition amount of a pure iron particle, and the saturation magnetic flux density Bs in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the addition amount of a pure iron particle, and the iron loss Pcm in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the saturation magnetic flux density Bs and the iron loss Pcm in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the average particle diameter of an alloy particle, and a density in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the average particle diameter of an alloy particle, and saturation magnetic flux density Bs in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the average particle diameter of an alloy particle, and the iron loss Pcm in the powder magnetic core obtained in the Example. It is a figure which shows the relationship between the saturation magnetic flux density Bs and the iron loss Pcm in the powder magnetic core obtained in the Example. In the examples, the state of pure iron particles when the surface is smoothed with a mechanofusion apparatus is shown, (A) is a micrograph showing the original particles before treatment, and (B) is the state after 2 minutes treatment. (C) is a photomicrograph showing the state after the treatment for 4 minutes, (D) is a photomicrograph showing the state after the treatment for 6 minutes, (E) is a photomicrograph showing the state after the treatment for 8 minutes, (F) is a photomicrograph showing the state after 10 minutes of treatment. It is a figure which shows the relationship between the bulk density of the pure iron particle of the Example at the time of performing surface smoothing with a mechano-fusion apparatus, and smoothing time. It is a figure which shows the relationship between smoothing time and specific resistance in the powder magnetic core obtained in the Example which smoothed the pure iron particle. It is a figure which shows the relationship between smoothing time and eddy current loss in the powder magnetic core obtained in the Example which smoothed the pure iron particle. It is a figure which shows the relationship between smoothing time and coercive force in the powder magnetic core obtained in the Example which performed the smoothing of the pure iron particle. It is a figure which shows the relationship between smoothing time and iron loss Pcm in the powder magnetic core obtained in the Example which smoothed the pure iron particle.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Composite soft magnetic material (powder magnetic core), 2 ... Fe-3Si alloy particle phase, 2a ... Grain boundary, 2b ... Grain boundary, 3 ... Pure iron particle phase, 4 ... Gap, 10 ... Reactor, 11a, 11b ... U-type core, 11c ... I-type core, 12 ... coil, 14 ... gap, 15 ... adhesive layer.

Claims (8)

 A composite soft magnetic material in which Fe-3Si alloy particles and pure iron particles are consolidated and fired, and is surrounded by a plurality of Fe-3Si alloy particle phases and at least three Fe-3Si alloy particle phases A plurality of pure iron particle phases existing at grain boundaries, the average particle size of the Fe-3Si alloy particle phase is 100 to 145 μm, and the content of the pure iron particle phase with respect to the total amount of the dust core is 3 A composite soft magnetic material, wherein the composite soft magnetic material is not less than 10% by mass and less than 10% by mass.  2. The composite soft magnetic material according to claim 1, wherein an average particle size of the pure iron particle phase is 10 μm or more and 50 μm or less.  It has an insulating layer in at least any one of the grain boundary between the Fe-3Si alloy particle phases, the grain boundary between the pure iron particles, and the grain boundary between the Fe-Si alloy particles and the pure iron particles. The composite soft magnetic material according to claim 1 or 2. A mixed particle is obtained by mixing Fe-3Si alloy particles having an average particle diameter of 100 to 145 μm and pure iron particles so that the content of the pure iron particles is 3% by mass or more and less than 10% by mass. 1 process,
A second step of obtaining a molded body by pressure-molding the mixed particles;
A composite soft magnetic material having a Fe-3Si alloy particle phase and a plurality of pure iron particle phases existing at a grain boundary surrounded by at least three Fe-3Si alloy particle phases by firing the compact. And a third step of obtaining the composite soft magnetic material.   The method for producing a composite soft magnetic material according to claim 4, wherein the surface of the pure iron particles is smoothed and mixed so as to be 3% by mass or more and less than 10% by mass. 6. The composite according to claim 4, wherein the bulk density (AD) of the pure iron particles is 0.09 to 0.25 Mg / m ³ higher than that of the pure iron particles before smoothing. A method for producing a soft magnetic material.   The method for producing a composite soft magnetic material according to any one of claims 4 to 6, further comprising a step of forming an insulating coating on at least one of the Fe-3Si alloy particles and the pure iron particles.  An electromagnetic circuit component comprising the composite soft magnetic material according to claim 1.

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