JP2020132896A - Soft magnetic alloy powder, method for producing the same, and dust core using the same - Google Patents

Abstract

To provide a soft magnetic alloy powder, so that an excellent magnetic property is obtained.SOLUTION: In the soft magnetic alloy powder 101 of the present invention, a heat-treated flat plate-shaped first powder 101 having a particle size of 40 μm or more and the value of major axis/minor axis of 1.2 or more and 2.0 or less, and a heat-treated flat plate-shaped second powder 102 having a particle size of 10 μm or more and 15 μm or less and the value of major axis/minor axis of 1.2 or more and 2.0 or less, are existing in a mixed manner.SELECTED DRAWING: Figure 1

Description

The present invention relates to a soft magnetic alloy powder used for inductors such as choke coils, reactors and transformers, a method for producing the same, and a powder magnetic core using the same.

In recent years, vehicles such as hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and electric vehicles (EV) have been rapidly electrified, and there is a demand for smaller and lighter systems in order to further improve fuel efficiency. There is. Driven by the electrification market, various electronic components are required to be smaller and lighter, and soft magnetic alloy powders used in choke coils, reactors, transformers, etc. and powder magnetic cores using them. On the other hand, higher performance is required.

This soft magnetic alloy powder and the powder magnetic core using it are required to have a high saturation magnetic flux density in order to reduce the size and weight, and further, to have a small core loss and excellent DC superimposition characteristics. Has been done.

For example, Patent Document 1 describes a method of realizing a small core loss and excellent DC superimposition characteristics, which are the characteristics of an amorphous soft magnetic alloy, by mixing pulverized powder and atomized spherical powder.

5 (a) to 5 (c) are diagrams for explaining the amorphous soft magnetic alloy described in Patent Document 1. FIG. 5A is a diagram showing a pulverized powder 1 having a particle size of 50 μm or more. FIG. 5B is a diagram showing a pulverized powder 2 having a particle size of 50 μm or less. FIG. 5C is a diagram showing atomized spherical powder 3.

Patent Document 1 describes a dust core containing the crushed powders 1 and 2 of these amorphous alloy strips and the amorphous alloy atomized spherical powder 3 as main components. This dust core is characterized by the following.

The crushed powders 1 and 2 are thin plates and have two facing main surfaces. When the minimum value in the plane direction of the main surface is taken as the particle size, the particle size exceeds twice (25 μm × 2 = 50 μm) of the thickness of the pulverized powder (thickness of the thin band 25 μm) and is 6 times (25 μm). × 6 = 150 μm) or less of the crushed powder 1 is 80% by mass or more of the total crushed powder. Moreover, the crushed powder 2 having a particle size of twice the thickness of the crushed powder (25 μm × 2 = 50 μm) or less is 20% by mass or less of the total crushed powder. Further, the particle size of the atomized spherical powder 3 is 1/2 (25 × 1/2 = 12.5 μm) or less and 3 μm or more of the thickness of the thin band (25 μm).

Japanese Patent No. 4944971

However, in Patent Document 1, the thin band crushed powders 1 and 2 are both flat, whereas the atomized spherical powder 3 is spherical. Therefore, when the crushed powders 1 and 2 and the atomized spherical powder 3 are mixed, the spherical powder cannot sufficiently fill the voids of the crushed powder. That is, when the atomized spherical powder 3 enters around the crushed powders 1 and 2, the shapes of the crushed powders 1 and 2 and the atomized spherical powder 3 are different, so that the contact area between the crushed powders 1 and 2 and the atomized powder 3 is large. It is small and the voids of the crushed powders 1 and 2 cannot be sufficiently filled with the atomized spherical powder 3. Therefore, the filling rate of the atomized spherical powder 3 does not increase, and the magnetic characteristics such as the relative permeability or the saturated magnetic flux density decrease.

The present invention solves the above problems, and an object of the present invention is to provide a soft magnetic alloy powder having excellent magnetic properties, a method for producing the same, and a powder magnetic core using the same.

In order to achieve the above object, the soft magnetic alloy powder of the present invention has a particle size of 40 μm or more, a major axis / minor axis value of 1.2 or more and 2.0 or less, and is a heat-treated flat plate. The first powder and the second powder having a particle size of 10 μm or more and 15 μm or less, a major axis / minor axis value of 1.2 or more and 2.0 or less, and a heat-treated flat plate-shaped second powder are mixed.

In order to achieve the above object, the powder magnetic core of the present invention includes the soft magnetic alloy powder and a binder.

In order to achieve the above object, the method for producing a soft magnetic alloy powder of the present invention includes a first processing step of processing a soft magnetic alloy strip into a coarse powder and a first processing step of crushing the crude powder into a fine powder. Two processing steps, a classification step of classifying the fine powder into a plurality of parts, a heat treatment step of applying heat treatment to each of the plurality of fine powders, and a mixing of the fine powders after the heat treatment step. It has a process.

As described above, according to the means disclosed in the embodiment, it is possible to provide a soft magnetic alloy powder having excellent magnetic properties, a method for producing the same, and a powder magnetic core using the same.

(A) is a diagram showing a soft magnetic alloy powder according to an embodiment of the present invention, and (b) is a diagram showing a conventional soft magnetic alloy powder. The figure which shows the manufacturing process of the fine powder of the soft magnetic alloy thin band of embodiment of this invention. Figures (a) to (b) show the pulverization mechanism of the fine powder of the soft magnetic alloy strip according to the embodiment of the present invention. (A) to (c) are SEM images of various powders according to the examples of the present invention, and (d) SEM images of soft magnetic alloy powders of Comparative Examples. (A) is a diagram showing a pulverized powder having a particle size of 50 μm or more described in Patent Document 1, (b) is a diagram showing a pulverized powder having a particle size of 50 μm or less described in Patent Document 1, and (c) is an atomized spherical shape. Diagram showing powder

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The embodiments shown below are merely examples, and do not exclude the application of various modifications and techniques not specified in the following embodiments.

In addition, in all the drawings for explaining the embodiment, the same elements may be given the same reference numerals in principle, and the description thereof may be omitted.

<Structure>
FIG. 1A is a cross-sectional view of the soft magnetic alloy powder 100 according to the embodiment of the present invention. As shown in FIG. 1A, the soft magnetic alloy powder 100 is a mixed powder of the first powder 101 after the heat treatment having a large particle size and the second powder 102 after the heat treatment having a small particle size.

The first powder 101 (fine powder after heat treatment) has a flat plate shape, a particle size D of 40 μm or more, and a plane major axis / minor axis value R (ratio of major axis to minor axis) of 1.2 or more and 2.0. The following powder. As will be described later, the first powder 101 is a pulverized powder that has been pulverized by being pulverized, and has been subjected to heat treatment.
The definition of the particle size D is a value of an average particle size d50% (μm) and a median diameter (number average) calculated using a laser particle size distribution meter. The ratio value is also the value calculated on the left. In the following, the diameters not specified are the same.

The second powder 102 (fine powder after heat treatment) is a flat powder having a particle size D of 10 or more and 15 μm or less and a plane major axis / minor axis value R of 1.2 or more and 2.0 or less. As will be described later, the second powder 102 is a pulverized powder that has been pulverized by being pulverized, and has been subjected to heat treatment.

The particle size D of the first powder 101 is preferably larger, preferably 50 μm or more. Further, the value R of the major axis / minor axis of the plane of the first powder 101 is preferably 1.4 or more and 1.6 or less.

The second powder 102 preferably has a small particle size, and preferably contains, for example, a powder having a particle size of less than 10 μm. Further, the value R of the major axis / minor axis of the plane of the second powder 102 is preferably 1.4 or more and 1.6 or less.

The first powder 101 and the first powder 101 are the first powder 101 because the second powder having a major axis / minor axis value R within the same range as the first powder 101 and having a particle size D smaller than that of the first powder 101 enters the first powder 101. 2 The contact area with the powder 102 becomes large, and the filling rate becomes high. The filling rate refers to the ratio of the area occupied by the first powder 101 and the second powder 102 in a region having a predetermined area such as the frame shown in FIGS. 1 (a) and 1 (b).

The thickness of each of the first powder 101 and the second powder 102 is preferably 1 μm or more and 50 μm or less, and more preferably 10 μm or more and 40 μm or less.

If the thickness of the first powder 101 and the second powder 102 becomes thicker, the characteristics cannot be improved due to the presence of the particles when a voltage or current is passed between the particles. Therefore, the thinner the thickness of the first powder 101 and the second powder 102, the more the thermal responsiveness of each powder is improved. By performing the heat treatment, the relative magnetic permeability and the saturation magnetic flux density for each particle size are obtained. Is improved. Here, the heat treatment for improving the heat response is a process for increasing the heat conduction of the powder. Specifically, it refers to a process such as making the temperature rise rate and the surface roughness of the powder uniform in order to instantly transfer the heat of each powder.

<Conventional example>
FIG. 1B is a cross-sectional view of a soft magnetic alloy powder obtained by mixing the pulverized powder and atomized powder of Patent Document 1, which is a conventional example. The mixed powder (soft magnetic alloy powder) shown in FIG. 1B is a mixed powder in which a pulverized powder 103 having a particle size of 20 μm or more and an atomized powder 104 having a particle size of 3 μm or more are mixed. In this soft magnetic alloy powder, the crushed powder 103 has a long spherical shape, whereas the atomized powder 104 has a substantially spherical shape. Therefore, when the crushed powder 104 enters around the crushed powder 103, the crushed powder 103 The contact area between the atomized powder 104 and the atomized powder 104 is small. Therefore, the filling rate of the pulverized powder 103 and the atomized powder 104 is lower than that of the soft magnetic alloy powder of the embodiment of the present invention shown in FIG. 1 (a). That is, there are many voids without powder.

<Manufacturing method>
Next, a method for producing a soft magnetic alloy powder according to an embodiment of the present invention and a method for producing a dust core according to an embodiment of the present invention will be described.

<Manufacturing method of soft magnetic alloy powder>
A method for producing the soft magnetic alloy powder 100 will be described with reference to FIG.

<Manufacturing of Fe-based soft magnetic alloy strip>
The Fe-based alloy composition alloyed by arc melting or the like is melted by high-frequency heating or the like, and then the melted Fe-based alloy composition is cooled by a liquid quenching method to obtain an Fe-based soft magnetic alloy ribbon. 201 is manufactured. At this time, the thickness of the Fe-based soft magnetic alloy strip 201 is preferably 20 μm or more and 40 μm or less.

The production of the soft magnetic alloy strip 201 accompanied by such a liquid quenching method can be carried out by using a single roll type production apparatus or a double roll type production apparatus.

<Primary processing process>
Next, as the first processing step, the soft magnetic alloy strip 201 is finely cut into a certain size (for example, 1 mm square) without using a crusher, and processed into a coarse powder 202.

In this way, by finely grinding the soft magnetic alloy strip 201 into coarse powder 202 before pulverization, it is possible to suppress the crushing energy generated during the subsequent pulverization. Examples of a device for finely cutting the soft magnetic alloy strip 201 include a microcut shredder, a cutting machine, and the like. The cutting machine uses a device that cuts the soft magnetic alloy strip 201 in the plane direction instead of the thickness direction. By reducing the soft magnetic alloy strip 201 in advance in this first processing step, a powder having a wide particle size distribution (fine powder 203) can be finally produced. The size of the crude powder 202 is preferably 1 mm square or less.

<Second processing process>
Next, the fine powder 203 is obtained by crushing the shredded coarse powder 202. A general pulverizer can be used for pulverizing the coarse powder 202, and for example, a ball mill, a stamp mill, a planetary mill, a cyclone mill, a jet mill, a rotary mill, or the like can be used.

Further, by classifying the fine powder 203 obtained by pulverization using a sieve, fine powders 204 and 205 having a desired particle size distribution can be obtained.

<Manufacturing mechanism of the secondary processing process>
Using FIGS. 3 (a) and 3 (b), a mechanism (manufacturing mechanism) in which the fine powder 203 in which the fine powder 204 and the fine powder 205 are mixed is produced from the crude powder 202 by the pulverizer will be described. To do. When the crude powder 202 shown in FIG. 3A is crushed with a crusher such as a rotary mill, the surface of the coarse powder 202 is cleaved, and as shown in FIG. 3B, the fine powder 205 is scraped off and crushed onto the surface. The fine powder 204 has a mark 204a, a particle size D of 20 μm or more, and has no corners and is rounded. Further, the surface of the fine powder 205 is also cleaved by the same mechanism, and has a rounded shape without corners.

The subsequent processing will be described again with reference to FIG.

<Classification process>
When the fine powder 203 is obtained by pulverization as described above, the fine powder 203 is classified to obtain the fine powders 204 and 205.

<Heat treatment process>
Next, the fine powder 204 and the fine powder 205 obtained by classification are heat-treated using a heat treatment apparatus, respectively. By this heat treatment, the internal strain generated by pulverization is removed from the fine powders 204 and 205, and the αFe crystal phase is precipitated on the fine powders 204 and 205. As a result, the first powder 101 and the second powder 102 in which the αFe crystal phase is precipitated are obtained. As the heat treatment apparatus, for example, a hot air furnace, a hot press, a lamp, a sheath metal heater, a ceramic heater, a rotary kiln and the like can be used. At this time, rapid heating using a hot press or the like is preferable because crystallization progresses further and cleavage of the surface of the fine powder 204 further progresses. Therefore, the proportion of the fine powder 205 having a small particle size can be increased.

It is preferable to divide the fine powders 204 and 205 according to the particle size and heat-treat each of them separately (change the heat treatment conditions) because heat is evenly transferred to the fine powders 204 and 205 and homogeneous and preferable characteristics are obtained. .. For example, the smaller particle size (fine powder 205) is heat-treated (maximum temperature) at 440 ° C. The larger particle size (fine powder 204) is heat-treated (maximum temperature) at 460 ° C. because heat transfer is slow. As described above, as the particle size is larger, the heat treatment temperature is raised so that the fine powders 204 and 205 can be heat-treated according to the respective particle sizes, and the fine powders 204 and 205 have uniform characteristics.

<Mixing process>
Next, the first powder 101 and the second powder 102 in which the αFe crystal phase is precipitated are mixed using a mixing device while considering the mixing amount. As a result, the soft magnetic alloy powder 100 is obtained.
As the mixing device, for example, a stirrer, a mixer, or the like can be used. In the mixing step, the relative magnetic permeability and the saturation magnetic flux density can be improved by changing the mixing ratio of the first powder 101 and the second powder 102 and controlling the particle size so as to improve the filling rate. .. Here, the particle size is the average particle size when a laser diffraction particle size distribution meter is used. For example, when the proportion of particles having a large particle size is increased, there is no room for particles having a small particle size to enter between the particles having a large particle size, so that the average particle size becomes large, and the first powder 101 and the second powder 102 The particle size can be controlled by changing the mixing ratio.

<Manufacturing of dust core>
A method for producing a powder magnetic core containing the soft magnetic alloy powder 100 and a binder according to the embodiment of the present invention will be described. In the production of the powder magnetic core according to the present embodiment, first, the first powder 101, the second powder 102, and a binder having good insulation and high heat resistance such as phenol resin and silicone resin are mixed and stirred using a mixing stirrer. , Manufacture granulated powder.

Next, this granulated powder is filled in a highly heat-resistant mold having a desired shape and pressure-molded to obtain a green compact. Then, by heating this powder compact at a temperature at which the binder cures, a powder magnetic core having a high relative permeability and a high saturation magnetic flux density can be obtained.

(Example 1)
As the soft magnetic alloy strip 201, an Fe-based soft magnetic alloy strip 201 having a thickness of 20 μm or more and 40 μm or less of Fe73.5-Cu1-Nb3-Si13.5-B9 (atomic%) was produced by a quenching single roll method.

The soft magnetic alloy strip 201 was shredded into 10 mm squares to produce a crude powder 202.

Then, the crude powder 202 was pulverized with a rotary mill to obtain a fine powder 203 which is a pulverized powder of a soft magnetic alloy. In this pulverization, coarse pulverization was carried out for 3 minutes and fine pulverization was carried out for 20 minutes. The fine powder 203 was classified into fine powder 204 and fine powder 205, which are soft magnetic alloy powders having desired particle size distributions, respectively, using a sieve. The fine powders 204 and 205 obtained by classification were heat-treated, respectively, to obtain a first powder 101 and a second powder 102 in which the α-Fe crystal phase was precipitated. Finally, the first powder 101 and the second powder 102 in which the α—Fe crystal phase was precipitated were mixed to obtain a soft magnetic alloy powder 100.

Next, the soft magnetic powder 100 was granulated using the silicone resin as a binder to produce the granulated powder.

Next, the granulated powder is put into a mold, and the granulated powder put into the mold is pressure-molded at a pressure of 4 tons / cm ² using a press machine to obtain a green compact. Manufactured. At this time, a plurality of green compacts were produced by the same method.

For each of the obtained green compacts, the relative magnetic permeability at a frequency of 100 kHz was measured using an impedance analyzer. When the pass / fail standard of magnetic permeability was set to 25 or more, all the green compacts cleared the pass / fail standard. That is, the magnetic permeability of all the green compacts was 25 or more. The pass / fail criteria were set to be equal to or higher than the relative magnetic permeability of conventional metallic materials. Therefore, a powder magnetic core having a high relative magnetic permeability was obtained.

(Comparative Example 1)
As the soft magnetic alloy strip, a Fe-based strip having a thickness of 20 μm or more and 40 μm or less of Fe73.5-Cu1-Nb3-Si13.5-B9 (atomic%) was produced by a quenching single roll method. This thin band was shredded into 10 mm squares to obtain a coarse powder.

This crude powder was pulverized using a rotary mill to obtain a fine powder which is a pulverized powder of a soft magnetic alloy strip. In this pulverization, coarse pulverization was carried out for 3 minutes and fine pulverization was carried out for 20 minutes. The pulverized powder was classified using a sieve to obtain a pulverized powder of a soft magnetic alloy having a desired particle size distribution. The obtained pulverized powder was heat-treated to obtain a fine powder (soft magnetic powder) in which the α-Fe crystal phase was precipitated.

Next, the granulated powder of the soft magnetic powder, which is a fine powder, was produced using a silicone resin as a binder.

Next, the granulated powder was put into a mold and pressure-molded at a pressure of 4 tons / cm ² using a press machine to produce a green compact. At this time, a plurality of green compacts were produced by the same method.

For each of the obtained green compacts, the relative magnetic permeability at a frequency of 100 kHz was measured using an impedance analyzer. When the pass / fail criteria for the specific magnetic permeability was set to 25 or more as in the examples, there was no green compact that cleared the pass / fail criteria. As described above, the pass / fail criteria are set so as to be equal to or higher than the relative magnetic permeability of the conventional metal-based material.

<Shape of fine powder after heat treatment>
As described above, the green compact of the example and the green compact of the comparative example are each subjected to heat treatment using the crushed crushed powder using a rotary mill, so that the surface is cleaved and the particle size is increased. Has no corners of 20 μm or more and has a rounded shape.

<Particle size distribution>
The particle size distribution of the pulverized powder of each soft magnetic alloy strip obtained by pulverization was measured using the Microtrack MT3000 (2) series. FIG. 4A shows an SEM image of the second powder 102 that has been heat-treated after the classification of Example 1. FIG. 4B shows an SEM image of the first powder 101 that has been heat-treated after the classification of Example 1. The particle size of the second powder 102 shown in FIG. 4A is 10 μm or more and 15 μm or less, and the particle size of the first powder 101 shown in FIG. 4B is 40 μm or more and 50 μm or less. FIG. 4 (c) shows the powder when the fine powders of FIGS. 4 (a) and 4 (b) are mixed, that is, the soft magnetic alloy powder 100 of Example 1.

FIG. 4D is the soft magnetic alloy powder 404 of Comparative Example 1. The soft magnetic alloy powder 404 of Comparative Example 1 has a particle size that is not uniform after pulverization, and is a powder having a particle size of 10 μm or more and 20 μm or less.

The cumulative distribution of the soft magnetic alloy powder 100 of Example 1 in FIG. 4 (c) was 7.032 μm for D10%, 14.48 μm for D50%, and 37.81 μm for D90%, which are average particle diameters.

On the other hand, in the soft magnetic alloy powder 404 of Comparative Example 1 in FIG. 4 (d), the average particle size of D10% was 7.153 μm, D50% was 14.13 μm, and D90% was 29.99 μm.

Here, D10% is a particle size of 10% below the number standard. D50% is a particle size of 50% below the number standard. D90% is a particle size of 90% below the number standard.

The following is a summary in Table 1.

The value of D10% / D90%, which is the ratio of the cumulative distribution, was 0.185 in the soft magnetic alloy powder 100 of Example 1 in FIG. 4 (c). It was 0.239 in the soft magnetic alloy powder 404 of Comparative Example 1 in FIG. 4 (d). The smaller this value, the wider the width of the particle size distribution of the soft magnetic alloy powder. That is, the proportion of fine particles in the soft magnetic alloy powder increases. In the soft magnetic alloy powder 100 of Example 1, the first powder 101 and the second powder 102, which are the powders after the heat treatment, were mixed at a ratio of 30% and 70%.

Therefore, in the cumulative distribution of the pulverized powder in the soft magnetic alloy powder 100, when the average particle size D50% is 14 μm, the cumulative distribution ratio D10% / D90% is preferably less than 0.200.

When the target value is that D50%, which is the average particle size, is within the range of 10 μm or more and 20 μm or less, if the proportion of fine particles is large and the proportion of coarse particles is small, the fine particles enter the voids in the coarse particles and have a density. Is improved. Therefore, it is preferable that the value of D10%, which is the average particle size, is smaller, and the value of D10% / D90%, which indicates that the particle size distribution width is wide, is small. Moreover, since the particle size is uniform by performing the heat treatment for each particle size, the amount of heat applied to each powder becomes equal, and it is possible to precipitate αFe crystals having a uniform size, which leads to further improvement in characteristics. ..

The cumulative distribution of the pulverized powder in the soft magnetic alloy powder 100 is such that D10% is less than 10 μm, D50% is 10 μm or more and 20 μm or less, and D90% is 30 μm or more, and the cumulative distribution ratio of D10% / D90% is , 0.20 or less is preferable.

As described above, the soft magnetic alloy powder 100 of Example 1 obtained by mixing the powders (first powder 101 and second powder 102) heat-treated according to the particle size is the soft magnetic alloy of Comparative Example 1. It is possible to create a broad particle size distribution having a wider particle size distribution range than the powder 404. As a result, since the proportion of the fine particles is increased, the second powder 102 can easily enter the first powder 101.

Further, the soft magnetic alloy powder 100 is composed of only the powder after pulverization, and the powder after pulverization has substantially the same shape, so that the porosity is low. Therefore, the soft magnetic alloy powder 100 is a soft magnetic alloy powder having high magnetic permeability and high saturation magnetic flux density and excellent magnetic characteristics.

From this result, by mixing the first powder 101 and the second powder 102 which are the powders after the heat treatment, it is possible to mix them at a mixing ratio in which the porosity is reduced, and the specific magnetic permeability and the saturation magnetic flux density are improved. be able to.

<Mixed>
Therefore, it is preferable to mix the powders according to the particle size based on the process of the soft magnetic alloy powder 100. That is, the powder 203 which was crushed by a crusher and classified to a 53 μm sieve was further classified to a 32 μm sieve. At that time, the classified powder 204 having a large particle size and the powder 205 having a small particle size are produced. The powders 204 and 205 are separately heat-treated, and the mixed powder becomes the soft magnetic alloy powder 100.

Further, in producing the soft magnetic alloy powder 100 after the heat treatment, by setting the mixing ratio of the first powder 101 and the second powder 102 to an appropriate value, a powder having a higher filling rate and a higher specific magnetic permeability can be produced. can do.

Table 2 below shows the measurement results of Example 2 in addition to the above-mentioned Example 1. Examples 1 and 2 are a mixture of the first powder 101 and the second powder 102, which are the powders after the heat treatment, respectively.

The value of D10% / D90%, which is the ratio of the cumulative distribution, was 0.185 in Example 1 and 0.134 in Example 2. The smaller this value, the wider the particle size distribution. That is, the proportion of fine particles increases.

At this time, the powder of Example 1 (soft magnetic alloy powder 100) was a mixture of the first powder 101 and the second powder 102 at a ratio of 30% and 70%. In the powder of Example 2 (soft magnetic alloy powder 100), the first powder 101 and the second powder 102 after the heat treatment were mixed at a ratio of 50% and 50%.

Therefore, the value of D10% / D90%, which is the ratio of the cumulative distribution of the first powder 101 and the second powder 102, is preferably less than 0.150.

When the target is that the average particle size D50% is within the range of 10 μm or more and 20 μm or less, if the proportion of fine particles is large and the proportion of coarse particles is small, the fine particles enter the voids in the coarse particles and the density becomes high. improves. Therefore, it is preferable that the value of D10%, which is the average particle size, is smaller, and the value of D10% / D90%, which indicates that the particle size distribution width is wide, is smaller. Moreover, by changing the mixing ratio for each particle size (mixing ratio of the first powder 101 and the second powder 102), a powder having a higher filling rate can be produced.

The cumulative distribution of the first powder 101 and the second powder 102 after the heat treatment is D10% less than 10 μm, D50% 10 μm or more and 20 μm or less, and D90% 30 μm or more, which is the ratio of the cumulative distribution D10% /. D90% is preferably 0.20 or less.

As described above, by mixing the powders (first powder 101 and second powder 102) that have been heat-treated for each particle size, a broad particle size distribution having a wider particle size distribution range can be created as compared with the comparative example. .. As a result, since the proportion of the fine particles is increased, the second powder 102 can easily enter the first powder 101.

Further, only crushed fine powder (crushed powder) is used, and since fine powders having different particle sizes have the same shape, the porosity is low. Therefore, a soft magnetic alloy powder having high magnetic permeability and high saturation magnetic flux density and excellent magnetic properties can be obtained.

From this result, the porosity can be reduced, and the relative magnetic permeability and the saturation magnetic flux density can be improved by adjusting the mixing ratio of the heat-treated first powder 101 and the second powder 102.

<Effect of the present invention>
The effect of the present invention will be described again with reference to FIGS. 4 (a), 4 (b) and 4 (c). By heat-treating the pulverized fine powders 205 and 204 having the same particle size according to the calorific value of each powder, the second powder 102 and FIG. 4 (b) shown in FIGS. 4 (a) and 4 (b) are subjected to heat treatment. A powder having excellent soft magnetic properties such as the first powder 101 can be obtained. By mixing the second powder 102 and the first powder 101 after the heat treatment at a mixing ratio that leads to an increase in density, the relative magnetic permeability and the saturation magnetic flux density can be improved.

As described above, by reducing the value of the cumulative distribution ratio of D10% / D90%, that is, by widening the particle size distribution width, it is possible to produce a soft magnetic alloy powder in which fine powders of various sizes are mixed. Further, since the ratio of the fine powder is large, the fine powder can enter around the coarse powder, and the porosity in the soft magnetic alloy powder can be reduced.

Further, as shown in FIG. 1A, the soft magnetic alloy powder 100 has only the flat powders 101 and 102. That is, it is composed of powders 101 and 102 having the same shape. For this reason, it becomes easier to fill the voids than the mixed powder obtained by mixing the crushed powder 103 and the atomized powder 104 of FIG. 1B, which is a conventional example. As a result, the present embodiment composed of only the flat powders 101 and 102 of FIG. 1 (a) as compared with the conventional example which is a mixed powder of the crushed powder 103 and the atomized powder 104 shown in FIG. 1 (b). Since the soft magnetic alloy powder 100 has a lower porosity, the relative magnetic permeability and the saturation magnetic flux density are improved.

According to the embodiment of the present invention, the relative magnetic permeability of the soft magnetic alloy powder and the saturation magnetic flux density can be improved. That is, it is possible to provide a soft magnetic alloy powder having excellent soft magnetic properties.

1 Milled powder
2 Crushed powder 3 Atomized spherical powder 100 Soft magnetic alloy powder 101 First powder (fine powder after heat treatment)
102 Second powder (fine powder after heat treatment)
103 Crushed powder 104 Atomized powder 201 Soft magnetic alloy strip 202 Coarse powder 203, 204, 205 Fine powder after crushing 204a Crushing marks

Claims (10)

A flat first powder having a particle size of 40 μm or more and a major axis / minor axis value of 1.2 or more and 2.0 or less.
A soft magnetic alloy powder having a particle size of 10 μm or more and 15 μm or less, a major axis / minor axis value of 1.2 or more and 2.0 or less, and a plate-like second powder mixed. The soft magnetic alloy powder according to claim 1, wherein the thickness of each of the first powder and the second powder is 1 μm or more and 50 μm or less. The soft magnetic alloy powder according to claim 1 or 2, wherein the cumulative distribution of the soft magnetic alloy powder is D10% less than 10 μm, D50% 10 μm or more and 20 μm or less, and D90% 30 μm or more. The soft magnetic alloy powder according to claims 1 to 3, wherein D10% / D90%, which is the cumulative distribution ratio of the soft magnetic alloy powder, is 0.20 or less. The soft magnetic alloy powder according to any one of claims 1 to 4,
A powder magnetic core containing a binder. The first processing step of processing the soft magnetic alloy strip into coarse powder, and
The second processing step of crushing the crude powder into a fine powder, and
A classification step of classifying the fine powder into a plurality of powders,
A heat treatment step in which each of the fine powders divided into the plurality of pieces is heat-treated,
A method for producing a soft magnetic alloy powder, which comprises a mixing step of mixing the fine powder after the heat treatment step. The method for producing a soft magnetic alloy powder according to claim 6, wherein the soft magnetic alloy strip is produced by quenching a melt of the soft magnetic alloy. The production of the soft magnetic alloy powder according to claim 6 or 7, wherein in the mixing step, the fine powders divided into the plurality of parts are mixed at a mixing ratio such that the value of D10% / D90% is 0.20 or less. Method. The method for producing a soft magnetic alloy powder according to any one of claims 6 to 8, wherein the conditions of each of the heat treatments are different from each other. The method for producing a soft magnetic alloy powder according to any one of claims 6 to 9, wherein each of the heat treatments is a hot press.