JP2000282104A - Soft magnetic metal powder, powder aggregate and compression molded body - Google Patents

Abstract

(57) [Problem] To provide a compression molded body capable of simultaneously obtaining a high saturation magnetic flux density and a high magnetic permeability, and to provide a soft magnetic metal powder for the molded body and this aggregate. SOLUTION: The soft magnetic metal powder 1 according to the present invention has a major axis L and a minor axis D orthogonal to the major axis L, and has an outer shape of a cross section in a minor axis D direction crossing the major axis L. The outer surface is formed into a curved shape by being a curve and this curve is continued in the direction of the long axis L, and both end portions of the long axis L are formed into a convex curved surface. When the maximum length L1 and the maximum diameter of the minor axis D are D1, the aspect ratio L1 / D1 is 1.5 to 10, preferably 3 to 8.
It has been.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic metal powder, a powder aggregate, and a compact, and is used, for example, for magnetic materials used in high-frequency magnetic circuits and the like, mechanical parts, and the like.

[0002]

2. Description of the Related Art High magnetic permeability and low iron loss are required for a magnetic core used in a high-frequency magnetic circuit or the like. In addition, in recent years, as the frequency has been increasing in response to the increase in the screen size and the brightness of the television, the saturation magnetic flux density of the conventional ferrite core has been low, so the soft magnetic metal powder has been used to increase the magnetic flux density. Magnetic permeability and low iron loss are required. In order to obtain high magnetic permeability, it is necessary to increase the density of the magnetic powder constituting the magnetic core and to reduce the demagnetizing coefficient of the magnetic powder alone.

[0003] For this reason, the binder is mixed as much as possible by using a spherical powder and a powder having an ideal distribution of particle diameters (or particle diameters). Attempts have been made to obtain a molded core, or to form a flaky or scaly powder and mix it with a binder to form a magnetic core. In order to obtain a high magnetic permeability, the demagnetizing field coefficient may be reduced, and the aspect ratio of the soft magnetic metal powder (length / width ratio,
It is important to increase the aspect ratio.

[0004] For this reason, flaky powder having a flat shape by an atomizing method, centrifugal quenching method, roll method, etc., and flaky powder obtained by crushing a thin ribbon (ribbon) have been proposed. These have an aspect ratio of about 30
To 100 (for example, see JP-A-5-295402).

[0005]

The ideal powder for performing high-density molding is a powder obtained by ideally distributing the particle diameter (particle size) of a spherical powder, mixing the binder as little as possible and applying vibration or high pressure. By press molding, high-density molding can be performed while the powder particles press each other and move so as to fill the gaps between the particles. However, when the magnetic powder alone is a sphere, the demagnetizing field coefficient is as large as 0.33, so that the effective magnetic permeability as a magnetic core is reduced. On the other hand, in order to reduce the demagnetizing field coefficient of the magnetic powder alone, it has been attempted to form a flaky or scaly powder and mold it.However, even if these powders are mixed with a binder and subjected to vibration or pressure, they are originally The thickness of the powder is as thin as a few microns, so the difference between the thickness of the binder existing between the particles and the thickness of the magnetic powder is small, and pressure is applied in the thickness direction of the powder to fill the gap created by the powder being staggered. In fact, even if it is applied to a thin piece or scale, it is not possible to obtain a magnetic core having a high magnetic permeability because a force to move in the length direction does not work so as to fill the gap, so that high density molding cannot be performed.

Although the shape of the conventional soft magnetic metal powder described above has a high aspect ratio, its thickness is several μm, and is obtained by mixing with a binder and compression-molding. The soft magnetic metal compression-molded body has a large volume occupied by the binder, in other words,
The ratio of the soft magnetic powder in the compression molded body is reduced, and it is difficult to achieve high saturation magnetic flux density and high magnetic permeability at the same time. Accordingly, there is a demand for a powder that can be formed at a high density and that can reduce the demagnetizing coefficient of the magnetic powder alone constituting the magnetic core.

According to the present invention, the demagnetizing field coefficient can be reduced by forming the shape of the soft magnetic metal powder, in particular, the outer shape into a curved surface (irregular curved surface), and the aspect ratio is 1.5 to 10 and preferably 3 to 3. By setting the number to -8, it is an object to reduce the mixing ratio of the binder when molding this powder aggregate.

[0008]

The soft magnetic metal powder according to the present invention has a major axis L and a minor axis D orthogonal to the major axis L in order to achieve the above object. The outer shape of the cross section in the direction of the short axis D crossing L is a curve, and this curve is continuous in the direction of the long axis L so that the outer surface is curved and both ends of the long axis L It is formed on a convex curved surface, and further has a maximum length L1 of the major axis L,
When the maximum diameter of the short axis D is D1, the aspect ratio L1 / D1 is 1.5 to 10, preferably 3 to 8 (claim 1).

According to the soft magnetic metal powder having such a constitution, the demagnetizing coefficient can be reduced as compared with the spherical powder, and the mixing ratio of the binder can be reduced by defining the aspect ratio as described above. is there. The outer shape of the soft magnetic metal powder according to claim 1 is such that the cross-sectional shape in the major axis L direction has an elongated spheroid or a concave curved surface part constricted halfway in the major axis L direction of the elongated spheroid. It is desirable that (claim 2). Claim 1
Alternatively, the soft magnetic metal powder described in 2 is preferably an amorphous powder (claim 3).

This is because amorphous powder (non-crystalline powder) has a high degree of magnetic permeability without crystal magnetic anisotropy due to irregular arrangement of constituent atoms. Further, the powder aggregate according to claim 4 has a major axis L and a minor axis D orthogonal to the major axis L, and the outer shape of the cross section in the minor axis D direction crossing the major axis L is curved. When the curve is continuous in the direction of the major axis L, the outer surface has a curved shape, and both end portions of the major axis L are formed as convex curved surfaces, and further, the cross-sectional shape in the major axis L direction A soft magnetic metal powder (first powder) having an elongated spheroid or a shape having a concave curved portion constricted halfway in the major axis L direction of the elongated spheroid, and a spherical outer shape (sphere) Of the formed soft magnetic metal powder (second powder) and the soft magnetic metal powder (third powder) whose outer shape is formed into a flat ellipsoid, the first powder is the second powder or the third powder. Characterized in that at least one or both are mixed at least That.

In the powder aggregate according to the fourth aspect, the first
The aspect ratio of the powder can be arbitrarily set, but the aspect ratio of the first powder is preferably 1.5 to 10, preferably 3 to 8 (claim 5). Furthermore, the first to first
3 Since the particle diameter of the powder is 3 μm to 300 μm,
Although the mixing percentage of the first powder can be arbitrarily set, it is recommended that the mixing percentage of the first powder be 30% or more (claim 6). Further, according to the compression-molded body obtained by kneading the powder aggregate according to any one of claims 4 to 6 with a binder and compression-molding (claim 7), soft magnetic powder of an elongated spheroid is mixed. Therefore, the compact has a higher magnetic permeability than the compact consisting of the spherical powder group or the flat ellipsoidal powder group, and also has a smaller mixing ratio of the binder and a lower volume ratio of the magnetic metal powder. Is about 90%, and since the volume ratio of the powder is about 50% in the compact obtained by similarly molding the flake powder or the like, the compression-molded body of the present invention according to claim 7 is Because of the high saturation magnetic flux density and the soft magnetic metal powder in the shape of an elongated spheroid, the compacted (compressed) compact obtained by kneading with the binder exhibits good interparticle insulation. , Eddy currents between particles are generated even in the high frequency range. As a result, not only is it possible to obtain a high high-frequency magnetic permeability, but also because it has an elongated spheroidal shape, it is difficult to break through the insulating layer (binder layer) and insulation between particles can be improved well. (Claim 7).

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Soft magnetic metal powder 1 according to the present invention
1 to 4 (however, the powder 1
Has a particle diameter of 3 μm to 300 μm.
FIG. 4 shows an enlarged view). The powder 1 shown in FIG.
It has a major axis L and a minor axis D orthogonal to the major axis L, and the outer shape of the cross section in the minor axis D direction crossing the major axis L is a curve Q. The outer surface has a curved shape by being continuous in the directions, and both end portions of the long axis L are formed as convex curved surfaces 1A and 1B.
The cross-sectional shape in the direction of the major axis L is an elongated ellipsoid (the outer shape when rotated about the major axis L is an elongated spheroid).

The powder 1 shown in FIG.
One of A and 1B is formed to be larger than the other, and has a concave curved surface portion 1C in the middle of the long axis L direction, in the figure, closer to the convex curved surface 1A side, and has a so-called French bread shape. ing. The powder 1 shown in FIG.
The outer shape is a so-called sea cucumber shape having a concave curved surface portion 1C, and the powder 1 shown in FIG. 4 has a so-called gourd (gourd) shape having an outer shape having a concave curved surface portion 1C.

In any of the powders 1 shown in FIGS. 1 to 4, when the maximum length of the major axis L is L1 and the maximum diameter length D1 of the minor axis D is 1.5, the aspect ratio L1 / D1 is 1.5. -10, preferably 3-8. Powder 1 shown in FIGS. 1 to 4
In each case, the molten metal (molten metal) of the soft magnetic material is 15 to 7
The droplets are separated by an inert gas jet of 0 kg / cm ² of argon, nitrogen, or the like to form droplets, and the droplets are rushed into a high-speed swirling water stream (combined atomization of gas atomization and water atomization). Although the powder 1 obtained in this manner does not have to be an amorphous powder, the amorphous powder has a high degree of magnetic permeability due to an irregular arrangement of constituent atoms, which eliminates crystal magnetic anisotropy. Is recommended.

As the soft magnetic material, Fe--Si
-B-based metal material, Fe-Cr-Si-BC-based metal material or Fe-Si-B-based material, Nb, C,
A material containing one or more of Zr and Cu can be given. Referring to FIG. 7, the aspect ratio (L1 / D
An example of a spherical (spherical) soft magnetic metal powder 10 in which 1) is substantially 1 is shown, and it is known that this powder 10 can be obtained by a gas atomizing method. That is, the powder 10 is a result of spheroidization due to surface tension of the melt due to simultaneous solidification and cooling.

Referring to FIG. 8, there is shown an example of the soft magnetic powder 11 which is an elongated ellipsoid centered on the rotation axis 0 and has a thin flat ellipsoidal outer shape with a thickness t of several μm. The powder 11 has an aspect ratio L1 / D
Although 1 has a high aspect ratio such as 30 to 100, but is flat, the proportion occupied by the binder is high. 5 and 6, the powder 1 according to the present invention (hereinafter, referred to as a first powder), the spherical powder 10 (hereinafter, referred to as a second powder), and the oblate ellipsoidal powder 1
1 (hereinafter, referred to as a third powder).

FIG. 5 shows the relationship between the aspect ratio of the first powder 1 and the third powder 11 and the demagnetizing factor N. FIG. 6 shows the high frequency and the magnetic permeability of the first powder 1 and the second powder. Shows the relationship. As is clear from FIG. 5, the first powder 1 according to the present invention has a lower demagnetizing coefficient than the third powder 11 (since the aspect ratio of the second powder 10 is 1, Of course, the demagnetizing factor does not decrease). In addition, as is apparent from FIG. 6, the first powder 1 according to the present invention has a higher magnetic permeability than the second powder 10.

Further, the first powder 1 according to the present invention has an aspect ratio L1 / D1 of 1.5 to 10, preferably 3 to 8, so that an insulating binder is kneaded with the first powder 1. For example, when a doughnut-shaped compression molded body 20 shown in FIG. 9 is formed by compacting, a compact 20 having a powder ratio substantially equal to that of the spherical powder can be obtained. Magnetic susceptibility can be secured together. That is, the volume ratio of the first powder 1 according to the present invention is as high as about 90%, and the volume ratio of the third powder 11 is high, while the volume ratio is about 50%.
Both high saturation magnetic flux density and high magnetic permeability could be secured.

Further, the first powder 1 according to the present invention has a long axis L
And a short axis D orthogonal to the long axis L. The contour of the cross section in the short axis D direction crossing the long axis L is a curve Q, and this curve Q is continuous in the long axis L direction. As a result, the outer surface is formed into a curved surface shape, and both end portions of the long axis L are formed into convex curved surfaces 1A and 1B, and further, the cross-sectional shape in the long axis L direction is an elongated spheroid or the elongated ellipsoid. Is a soft magnetic metal powder having a concave curved surface portion 1C constricted halfway in the direction of the long axis L, so that even if the powder particles are kneaded with an insulating binder and compacted, the powder particles are insulated from each other. (Binder layer) is hardly broken through, and the insulation between the powder particles is improved.

The powder aggregate (powder group) according to the present invention
Is a group (aggregate) of the first powders 1 described above with reference to FIGS. 1 to 4 having different particle sizes because the particle size (particle size) is 3 μm to 300 μm and the particle size distribution is wide. Can also be configured. However, the present inventors have considered that the first
A powder aggregate in which at least one or both of the second powder 10 and the third powder 11 are mixed in the powder 1 has been developed. That is, the powder aggregate according to the present invention has a major axis L and a minor axis D orthogonal to the major axis L, and the outer shape of the cross section in the minor axis D direction crossing the major axis L is represented by a curve Q.
When the curve Q is continuous in the direction of the major axis L, the outer surface has a curved surface shape, and both end portions of the major axis L are formed as convex curved surfaces 1A and 1B. A soft magnetic metal powder (first powder) 1 having a concave curved surface portion 1C constricted halfway in the direction of the axis L, and a soft magnetic metal powder (second powder) having a spherical (spherical) outer shape. Powder) 10 and a soft magnetic metal powder (third powder) 11 whose outer shape is formed as a flat ellipsoid.
That is, at least one or both of the second powder 10 and the third powder 11 are mixed in the first powder 1.

Here, as long as at least one or both of the second powder 10 and the third powder 11 are mixed in the first powder 1, a conventionally known soft magnetic material such as a flaky powder or a scaly powder is used. One or more metal powders may be used as the fourth powder and the fifth powder (including the sixth or more powders). The mixing ratio (mixing percentage) of the first powder 1 is determined by the particle size of the powder 1, the second powder 10, and the second powder 10, 11.
Although it depends on the particle size of the first powder 1
Is desirably 30% or more.

An embodiment in which the second powder 10 and the second powder 11 are mixed in the first powder 1 will be described below.

[0023]

Embodiment 1 This embodiment 1 has a particle size of 250 to 400 μm.
A first powder 1 having an aspect ratio of about 3.5;
(Hereinafter referred to as "a" in Example 1), and a particle size of 150 to
A first powder 1 having a particle size of 250 to 150 μm and an aspect ratio of 1.7 to 3.6 (hereinafter referred to as “b” in Example 1), a particle diameter of 80 to 150 μm, and an aspect ratio of 1.1 to 1.7.
(Hereinafter, referred to as "c" in Example 1) is a microscopic photograph 1 (magnification ×
70), a is 8%, B is 55%, and C is 37%.

[0024]

Embodiment 2 This embodiment 2 has a particle size of 25 to 100 μm.
And a first powder 1 having an aspect ratio of 2.6 to 4 (hereinafter referred to as “a” in Example 2) and a particle size of 5 to 50 μm.
Is a photomicrograph 2 (magnification × 150) of a powder aggregate in which a spherical second powder 10 having an aspect ratio of 1 (hereinafter referred to as “b” in Example 2) is mixed. It is 60%.

[0025]

Embodiment 3 This embodiment 3 has a particle size of 150 to 500 μm.
In the first powder 1 having an aspect ratio of 2 to 6,
In this Example 3, it is referred to as "A").
3 is a photomicrograph 3 (magnification × 30) of a powder aggregate in which a third powder 11 (hereinafter, referred to as “b” in Example 3) of a flat ellipsoid having an aspect ratio of 2 to 4 in m is mixed;
The mixing ratio of A is 65%.

[0026]

Embodiment 4 This embodiment 4 has a particle size of 150 to 500 μm.
And a first powder 1 having an aspect ratio of about 3 (hereinafter referred to as "a" in Example 4) and a particle size of 50 to 150 μm.
And a spherical second powder 10 having an aspect ratio of 1 (hereinafter referred to as "b" in Example 4) and a particle size of 135 to 30.
FIG. 5 is a micrograph 4 (magnification × 30) of a powder aggregate in which a third ellipsoidal powder 11 having a 0 μm aspect ratio of 2 to 4 (hereinafter referred to as “c” in Example 4) is mixed. , The mixture ratio of B is 10%, and the mixture ratio of C is 45%.

[0027]

Example 5 The powder aggregates of Examples 1 to 5 were mixed with, for example, borosilicate glass 1 to 10% by weight as an insulating binder and consolidated by hot pressing under the conditions of 1.25 GPa and 723 k. Upon molding, a molded body 20 illustrated in FIG. 9 was obtained. The molded body 20 exhibited good interparticle insulation, and was low in generation of interparticle eddy current even in a high-frequency region, and was able to obtain high high-frequency magnetic permeability.

[0028]

As described above in detail, according to the present invention, it is possible to provide a compression molded body capable of simultaneously obtaining a high saturation magnetic flux density and a high magnetic permeability, and to provide a powder aggregate and a soft magnetic material as raw materials of the molded body. Metal powder can be provided.

[Brief description of the drawings]

FIG. 1 is an enlarged view showing a first example of a soft magnetic metal powder (first powder) according to the present invention.

FIG. 2 is an enlarged view showing a second example of the soft magnetic metal powder (first powder) according to the present invention.

FIG. 3 is an enlarged view showing a third example of the soft magnetic metal powder (first powder) according to the present invention.

FIG. 4 is an enlarged view showing a fourth example of the soft magnetic metal powder (first powder) according to the present invention.

FIG. 5 is a diagram illustrating a relationship between an aspect ratio and a demagnetizing coefficient, which is a comparison between a first powder and a third powder (a flat ellipsoidal powder).

FIG. 6 is a graph showing the relationship between high frequency and magnetic permeability showing a comparison between a first powder and a second powder (spherical powder).

FIG. 7 is an enlarged view of a second powder.

FIG. 8 is an enlarged view of a third powder.

FIG. 9 is a perspective view showing an example of a compression (consolidation) molded body.

FIG. 10 is a photomicrograph 1 of the powder aggregate according to Example 1.

11 is a photomicrograph 2 of the powder aggregate according to Example 2. FIG.

FIG. 12 is a micrograph 3 of a powder aggregate according to Example 3.

FIG. 13 is a photomicrograph 4 of the powder aggregate according to Example 4.

[Explanation of symbols]

 1 first powder 1A convex curved surface portion 1B convex curved surface portion 1C concave curved surface diagram

Continuing from the front page (72) Inventor Yoshimasa Okuno 1-1-1, Hama, Amagasaki-shi, Hyogo Inside Kubota Technology Development Laboratory Co., Ltd. (72) Inventor Hiroshi Yamamoto 1-1-1, Hama, Amagasaki-shi, Hyogo Kubota Technology Co., Ltd. Inside the development laboratory (72) Inventor Hideo Koshimoto 1-1-1 Hama, Amagasaki-shi, Hyogo F-term in Kubota Technology Development Laboratory Co., Ltd. (reference) 4K017 AA02 BB06 CA01 DA02 4K018 AA26 AA32 BB04 BB07 CA07 CA12 KA43

Claims (7)

[Claims] 1. A long axis L and a short axis D orthogonal to the long axis L, and a contour of a cross section in a direction of the short axis D crossing the long axis L is a curve, and the curve is the long axis. By being continuous in the direction of the axis L, the outer surface has a curved surface shape, and both end portions of the long axis L are formed in a convex curved surface.
The maximum length L1 of the major axis L and the maximum diameter of the minor axis D are D
1, the aspect ratio L1 / D1 is 1.5 to 10
A soft magnetic metal powder, desirably 3 to 8. 2. The powder according to claim 1, wherein the cross-sectional shape in the major axis L direction is an elongated spheroid or the major axis L of the elongated spheroid.
A soft magnetic metal powder having a shape having a concave curved surface part constricted halfway in the direction. 3. The soft magnetic metal powder according to claim 1, wherein the powder is an amorphous powder. 4. It has a major axis L and a minor axis D orthogonal to the major axis L, and the outer shape of a cross section in the minor axis D direction crossing the major axis L is a curve, and the curve is the length. By being continuous in the direction of the axis L, the outer surface has a curved surface shape, and both end portions of the long axis L are formed in a convex curved surface.
A soft magnetic metal powder (first powder) whose cross-sectional shape in the direction of the major axis L is a slender spheroid or a shape having a concave curved surface part constricted halfway in the direction of the major axis L of the slender spheroid.
And a soft magnetic metal powder (second powder) having an outer shape of a sphere (sphere) and a soft magnetic metal powder (third powder) having an outer shape of a flat spheroid. A powder aggregate, wherein at least one or both of the second powder and the third powder are mixed in the first powder. 5. The powder aggregate according to claim 4, wherein the first powder according to claim 4 has an aspect ratio L1 / D1 of 1.5 to 10, preferably 3 to 8. 6. A powder aggregate, wherein the percentage of the first powder according to claim 4 or 5 is 30% or more. 7. A compression-molded article obtained by kneading a binder to the powder aggregate according to any one of claims 4 to 6 and compression-molding the same.