BACKGROUND OF THE INVENTION
1. Field of the Invention

The present invention relates to a magnetic core containing a metal magnetic powder and a magnetic component.

2. Description of the Related Art

A magnetic core (dust core) containing a metal magnetic powder and a resin is used, for example, in magnetic components such as an inductor, a transformer, and a choke coil. Various attempts have been made on the magnetic core to improve various characteristics such as magnetic permeability.

For example, in JP 2004-197218 A and JP 2004-363466 A, attempts have been made to improve a packing rate of metal magnetic powder in a magnetic core and to improve magnetic permeability and a core loss (magnetic loss) by using a metal magnetic powder obtained by mixing a crystalline alloy powder and an amorphous alloy powder.

In addition, in JP 2011-192729 A, attempts have been made to improve the packing rate of the metal magnetic powder and to improve the magnetic permeability by using two kinds of metal magnetic powders different in a particle size and by adjusting a particle size ratio of the two kinds of metal magnetic powders within a predetermined range.

CITATION LIST
Patent Document

- Patent Document 1: JP 2004-197218 A
- Patent Document 2: JP 2004-363466 A
- Patent Document 3: JP 2011-192729 A

SUMMARY OF THE INVENTION

The present invention has been made in consideration of such circumstances, and an object thereof is to provide a magnetic core and a magnetic component capable of improving a core loss by an approach different from the related art.

To accomplish the object, a magnetic core according to an aspect of the present invention is a magnetic core containing metal magnetic particles. A total area ratio occupied by the metal magnetic particles on a cross-section of the magnetic core is 75% or more. The metal magnetic particles include, first large particles having an amorphous structure and having a Heywood diameter of 3 μm or more on the cross-section of the magnetic core, and second large particles having a nanocrystal structure and having a Heywood diameter of 3 μm or more on the cross-section of the magnetic core. An insulation coating of the first large particles is thicker than an insulation coating of the second large particles.

As a low loss material, a soft magnetic metal material having a nanocrystal structure has attracted an attention, but Bs tends to be lower in comparison to other soft magnetic metal materials. In addition, in order to increase Bs of the magnetic core, it is necessary to perform high-density packing of a magnetic powder, and thus high-pressure molding is required. In addition, in terms of materials, when using an amorphous material with high Bs, since an influence of magnetostriction is higher and a higher stress is required to perform high-density packing in comparison to a nanocrystalline material from material surface, it is considered that a hysteresis loss increases.

The present inventors found that a low-loss core that is not realized in a magnetic core obtained by simple mixing is realized by controlling the thickness of an insulation coating of first large particles having an amorphous structure and second large particles having a nanocrystal structure, and they accomplished the present invention. That is, it is considered that when making the insulation coating of the first large particles having the amorphous structure be thicker than the insulation coating of the second large particles, a buffer effect was obtained, and as a result, the low-loss core could be realized.

Preferably, T1/T2 is 1.3 to 40, and more preferably 1.3 to 20, in which an average thickness of the insulation coating of the first large particles is set to T1, and an average thickness of the insulation coating of the second large particles is set to T2.

The average thickness T2 of the insulation coating of the second large particles is preferably 5 to 50 nm.

The metal magnetic particles may include a particle group in which a Heywood diameter on the cross-section of the magnetic core is less than 3 μm. In addition, the particle group in which the Heywood diameter is less than 3 μm may include two or more kinds of small particles having coatings different composition to each other.

A magnetic component according to another aspect of the present invention includes the magnetic core described in any one of the aspects. The magnetic core is provided in various magnetic components such as an inductor, a choke coil, a transformer, and a reactor, and contributes to high efficiency of the magnetic component. Note that, the magnetic component is not limited to the magnetic component including the magnetic core, and may be a magnetic component that is not provided with the magnetic core.

For example, a magnetic component according to still another aspect of the present invention is a magnetic component including a magnetic body containing metal magnetic particles. A total area ratio occupied by the metal magnetic particles on a cross-section of the magnetic body is 75% or more. The metal magnetic particles include, first large particles having an amorphous structure and having a Heywood diameter of 3 μm or more on the cross-section of the magnetic body, and second large particles having a nanocrystal structure and having a Heywood diameter of 3 μm or more on the cross-section of the magnetic body. An insulation coating of the first large particles is thicker than an insulation coating of the second large particles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a cross-section of a magnetic core according to an embodiment;

FIG. 2A is a graph showing an example of a particle size distribution of metal magnetic particles;

FIG. 2B is a graph showing an example of the particle size distribution of the metal magnetic particles;

FIG. 2C is a graph showing an example of the particle size distribution of the metal magnetic particles;

FIG. 3A is an enlarged schematic view of a cross-section of the magnetic core shown in FIG. 1;

FIG. 3B is an enlarged schematic view of a cross-section of a magnetic core according to a second embodiment;

FIG. 4 is a schematic cross-sectional view showing an example of a powder treatment device that is used when forming an insulation coating on the metal magnetic particles; and

FIG. 5 is a cross-sectional view showing an example of a magnetic component.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, description is made on the basis of embodiments.

First Embodiment

A magnetic core 2 according to an embodiment shown in FIG. 1 may maintain a predetermined shape, and an external size or a shape thereof is not particularly limited. The magnetic core 2 contains at least metal magnetic particles 10 and a resin 20, and the metal magnetic particles 10 are dispersed in the resin 20. That is, the metal magnetic particles 10 are bound through the resin 20, and thus the magnetic core 2 has a predetermined shape.

A total area ratio A0 occupied by the metal magnetic particles 10 on a cross-section of the magnetic core 2 is preferably 75% or more. An upper limit of the total area ratio is not particularly limited, but A0 may be 90% or less or 89% or less from the viewpoint of reducing the core loss. Note that, from the viewpoint of increasing magnetic permeability, A0 is preferably as high as possible. The total area ratio A0 of the metal magnetic particles 10 corresponds to a packing rate of the metal magnetic particles 10 in the magnetic core 2, and may be calculated by performing analysis on the cross-section of the magnetic core 2 by using an electronic microscope such as a scanning electron microscope (SEM) and a scanning transmission electron microscope (STEM).

For example, observation is performed by dividing any cross-section of the magnetic core 2 into a plurality of continuous fields of view, and an area of each of the metal magnetic particles 10 included in each of the fields of view is measured. Then, the sum of the areas of the metal magnetic particles 10 is divided by a total area of the observed fields of view to calculate the total area ratio A0 (%) of the metal magnetic particles 10. In the cross-section analysis, the total area of the fields of view is preferably set to at least 1000000 μm².

In addition, in the cross-section analysis, in a case where a cut-out surface (a surface obtained by cutting out and polishing the magnetic core 2) of an observation sample is less than the total area of the fields of view, after analyzing a predetermined cut-out surface, the cut-out surface may be polished again by 100 μm or more, and the cross-section analysis may be performed again to set the total area of the fields of view to 1000000 μm²or more.

The metal magnetic particles 10 contained in the magnetic core 2 include a first particle group 10a in which a Heywood diameter is 3 μm or more, and preferably further includes a second particle group 10b in which a Heywood diameter is less than 3 μm. Here, the “Heywood diameter” in this embodiment represents a circle equivalent diameter of each of the metal magnetic particles 10 observed on the cross-section of the magnetic core 2. Specifically, an area of each of the metal magnetic particles 10 on the cross-section of the magnetic core 2 is set to S, and the Heywood diameter of each of the metal magnetic particles 10 is expressed by (4S/π)^1/2.

In a case where the metal magnetic particles 10 include the first particle group 10a and the second particle group 10b, in the magnetic core 2, a content rate of the first particle group 10a and a content rate of the second particle group 10b are not particularly limited, but from the viewpoint of increasing the magnetic permeability, it is preferable that the content rate of the first particle group 10a is more than the content rate of the second particle group 10b. That is, on the cross-section of the magnetic core 2, when a total area ratio occupied by first particle group 10a is set to AL and a total area ratio occupied by second particle group 10b is set to AS, the area ratio of the metal magnetic particles 10 preferably satisfies a relationship of AL>AS.

When the content rate of the first particle group 10a is set to be larger than the content rate of the second particle group 10b, the magnetic permeability of the magnetic core 2 can be improved. Note that, the sum of AL and AS becomes the total area ratio A0 of the metal magnetic particles 10 (AL+AS=A0), and AL and AS may be measured by a similar method as in A0.

In addition, the metal magnetic particles 10 preferably include two or more particle groups different in an average particle size. For example, the metal magnetic particles 10 may include at least large particles 11 corresponding to the first particle group 10a, but the metal magnetic particles 10 preferably include the large particles 11 and small particles 12, and may include other medium particles 13. The large particles 11, the small particles 12, and the medium particles 13 can be distinguished on the basis of a particle size distribution of the metal magnetic particles 10. The particle size distribution of the metal magnetic particles 10 may be specified by measuring the Heywood diameter of at least 1000 pieces of the metal magnetic particles 10 on any cross-section of the magnetic core 2.

For example, graphs exemplified in FIGS. 2A to 2C are particle size distributions of the metal magnetic particles 10. In the graphs of FIGS. 2A to 2C, the vertical axis represents an area-basis frequency (%), and the horizontal axis is a logarithmic axis representing a particle size (μm) in terms of the Heywood diameter. Note that, the particle size distributions shown in FIGS. 2A to 2C are illustrative only, and the particle size distribution of the metal magnetic particles 10 is not limited to FIGS. 2A to 2C.

In a case where the metal magnetic particles 10 are constituted by two particle groups (large particles and small particles) different in an average particle size, as shown in FIG. 2A, the particle size distribution of the metal magnetic particles 10 has two peaks. In addition, in a case where the metal magnetic particles 10 are constituted by three particle groups (a large particle, a medium particle, and a small particle) different in an average particle size, as shown in FIG. 2B, the particle size distribution of the metal magnetic particles 10 has three peaks.

As shown in FIGS. 2A and 2B, in a case where the particle size distribution of the metal magnetic particles 10 is expressed by a series of distribution curves, a particle group which belongs to a peak located on the largest diameter side (peak located on the rightmost side of the horizontal axis) and in which D20 is 3 μm or more is set as large particles 11, and a particle group which belongs to a peak located on the smallest diameter side (peak located on the leftmost side of the horizontal axis) and in which D80 is less than 3 μm is set as small particles 12. In addition, particles other than the large particles 11 and the small particles 12 are set as medium particles 13.

Here, the “particle group belonging to a peak located on the largest diameter side” represents a particle group included in a range from the bottom (the rightmost end) of the distribution curve to a local minimum point through a peak top point when tracing the distribution curve from the large diameter side (the right side of the graph). That is, in a case of the particle size distribution shown in FIG. 2A, a particle group included in a range from EP1 to LP through Peak 1 corresponds to the “particle group belonging to a peak located on the largest diameter side”. In a case of the particle size distribution shown in FIG. 2B, a particle group included in a range from EP1 to LP1 through Peak 1 corresponds to the “particle group belonging to a peak located on the largest diameter side”.

In addition, D20 represents a Heywood diameter in which an area-basis cumulative frequency is 20%. In the particle size distributions in FIGS. 2A and 2B, D20 of the particle group belonging to Peak 1 is 3 μm or more, and a particle group belonging to Peak 1 corresponds to the large particles 11.

The “particle group belonging to a peak located on the smallest diameter side” represents a particle group included in a range from the bottom (leftmost end) of the distribution curve to a local minimum point through a peak top point when tracing the distribution curve from the small diameter side (the left side of the graph). That is, in a case of the particle size distribution shown in FIG. 2A, a particle group included in a range from EP2 to LP through Peak 2 corresponds to the “particle group belonging to a peak located on the smallest diameter side”. In addition, in a case of the particle size distribution shown in FIG. 2B, a particle group included in a range from EP2 to LP2 through Peak 2 corresponds to the “particle group belonging to a peak located on the smallest diameter side”.

In addition, D80 represents a Heywood diameter in which an area-basis cumulative frequency becomes 80%. In the particle size distributions in FIGS. 2A and 2B, D80 of a particle group belonging to Peak 2 is less than 3 μm, and the particle group belonging to Peak 2 corresponds to the small particles 12.

Note that, in the particle size distribution shown in FIG. 2B, a particle group from LP1 to LP2 through Peak 3 is a particle group belonging to Peak 3. In the particle group belonging to Peak 3, D20 is less than 3 μm and D80 is 3 μm or more. That is, the particle group belonging to Peak 3 corresponds to medium particles 13 which correspond to neither the large particles 11 nor the small particles 12.

In a case where the metal magnetic particles 10 include two or more particle groups different in an average particle size, the small particles 12, and/or the medium particles 13 may have the same particle composition as in the large particles 11, or may have a particle composition different from the particle composition of the large particles 11. Note that, “different in a particle composition” represents a case where kinds of constituent elements contained in a particle main body are different from each other, or a case where content ratios of the constituent elements are different from each other even though kinds of the constituent elements match each other. The constituent elements represent elements contained in the particle main body in a ratio of 1 at % or more. That is, it is assumed that elements other than impurity elements among the elements contained in the particle main body are referred to as the constituent elements.

In a case where the small particles 12 and/or the medium particles 13 have a particle composition different from the particle composition of the large particles 11, the metal magnetic particles 10 may be classified by using composition analysis and particle size analysis in combination. Specifically, at the time of observing the cross-section of the magnetic core 2 by an electron microscope, the composition of each of the metal magnetic particles 10 included in an observation field of view is analyzed by using an energy dispersive X-ray analyzer (EDX device) or an electron probe microanalyzer (EPMA), and the metal magnetic particles 10 are classified on the basis of the composition. Then, a plurality of distribution curves are obtained by measuring the Heywood diameter of the metal magnetic particles 10 belonging to each composition.

For example, in a case where the metal magnetic particles 10 are constituted by four particle groups different in a particle composition, four distribution curves are obtained as shown in FIG. 2C. In the particle size distribution in FIG. 2C, a distribution curve of a particle group having Composition A is shown as a solid line, a distribution curve of a particle group having Composition B is shown as a dotted line, a distribution curve of a particle group having Composition C is shown as a one-dotted chain line, and a distribution curve of a particle group having Composition D is shown as a two-dotted chain line.

As shown in FIG. 2C, in a case where the particle size distributions of the metal magnetic particles 10 are expressed by a plurality of distribution curves corresponding to compositions, a particle group in which D20 is 3 μm or more is set as the large particles 11, a particle group in which D80 is less than 3 μm is set as the small particles 12, and particle groups other than the large particles 11 and the small particles 12 are set as the medium particles 13. That is, in FIG. 2C, the particle group having Composition A and the particle group having Composition B correspond to the large particles 11, the particle group having Composition C corresponds to the small particles 12, and the particle group having Composition D corresponds to the medium particles 13.

As described above, D20 of the large particles 11 is preferably 3 μm or more, and the Heywood diameter of the large particles 11 is preferably 3 μm or more in any particle. In addition, an average value (arithmetic average diameter) of the Heywood diameter of the large particles 11 is not particularly limited, and is preferably 5 to 40 μm, and more preferably 10 to 35 μm as an example. D80 of the small particles 12 is preferably less than 3 μm, and the Heywood diameter of the small particles 12 is preferably less than 3 μm in any particle. In addition, an average value (arithmetic average diameter) of the Heywood diameter of the small particles 12 is not particularly limited, and is preferably 2 μm or less, and more preferably 0.2 μm or more and less than 2 μm as an example.

As described above, when a total area ratio occupied by the large particles 11 on the cross-section of the magnetic core 2 is set as AL, and a total area ratio occupied by the small particles 12 on the cross-section of the magnetic core 2 is set as AS, AL is preferably larger than AS from the viewpoint of increasing the magnetic permeability (AL>AS). Note that, in this embodiment, even in a case where AL is equal to or less than AS, an effect of reducing the core loss can be realized.

Specifically, a ratio (AL/A0) of the total area of the large particles 11 to the total area of the metal magnetic particles 10 is not particularly limited, but may be 15% to 95%, and from the viewpoint of increasing the magnetic permeability, the ratio is preferably more than 50% and equal to or less than 90%, and more preferably 60% to 88%.

In addition, a ratio (AS/A0) of the total area of the small particles 12 to the total area of the metal magnetic particles 10 may be 5% to 85%, and the ratio is preferably 5% or more and less than 50% from the viewpoint of increasing the magnetic permeability, and more preferably 10% to 40%. When the magnetic core 2 contains the small particles 12 at the above-described ratio in combination with the large particles 11, the magnetic permeability can be improved. Note that, AL and AS described above may be measured by a similar method as in A0.

The metal magnetic particles 10 may include medium particles 13, and in a case of including the medium particles 13, an average value (arithmetic average diameter) of a Heywood diameter of the medium particles 13 is not particularly limited, and is preferably 3 to 5 μm as an example. In addition, a ratio (AM/A0) of the total area (AM) of the medium particles 13 to the total area (A0) of the metal magnetic particles 10 is preferably 30% or less, and more preferably 5% to 20%.

In addition, an average circularity of the large particles 11 on the cross-section of the magnetic core 2 is preferably 0.90 or more, and more preferably 0.95 or more. As the average circularity of the large particles 11 is higher, a withstand voltage and DC bias characteristics can be further improved. Note that, the circularity of the each of the large particles 11 is expressed by 2(πS_L)^1/2/L when an area of each of the large particles 11 on the cross-section of the magnetic core 2 is set as S_L, and a peripheral length of the large particle 11 is set as L. The circularity of a perfect circle is 1, and a spheroidicity of a particle becomes higher as the circularity is closer to 1. An average circularity of the large particles 11 is preferably calculated by measuring the circularity of at least 100 large particles 11.

Note that, the average circularity of the small particles 12 and the average circularity of the medium particles 13 are not particularly limited, but the small particles 12 and the medium particles 13 preferably have a high average circularity as in the large particles 11. Specifically, any of the average circularity of the small particles 12 and the average circularity of the medium particles 13 is preferably 0.80 or more.

Note that, in this embodiment, the methods shown in FIGS. 2A to 2C are suggested as a method of classifying the metal magnetic particles 10 into the large particles 11, the small particles 12, and the like, but it is preferable to use the classification method shown in FIG. 2A or 2B in a case where the small particles 12 have the same particle composition as in the large particles 11, and it is preferable to use the classification method shown in FIG. 2C in a case where the small particles 12 have a particle composition different from the particle composition of the large particles 11.

In the magnetic core 2 of this embodiment, the large particles 11 can be subdivided into two kinds of particle groups different in an intragranular substance state. Specifically, the large particles 11 include first large particles 11a having an amorphous structure and second large particles 11b having a nanocrystal structure.

Here, the “nanocrystal structure” represents a crystal structure in which the degree of amorphization X is less than 85%, and an average crystallite diameter is 0.5 to 30 nm. Note that, the “amorphous structure” represents a crystal structure in which the degree of amorphization X is 85% or more, and includes a structure consisting of a hetero-amorphous substance.

The structure consisting of the hetero amorphous substances represents a structure in which an initial fine crystal exists in the amorphous substance, and an average diameter of the initial fine crystal in the hetero amorphous structure is preferably 0.1 to 10 nm. Note that, in this embodiment, “crystalline structure” represents a crystal structure in which the degree of amorphization X is less than 85%, and the average crystallite diameter is 100 nm or more.

An intragranular crystal structure (that is, the degree of amorphization X or the crystallite size) can be specified by structure analysis using various electron microscopes such as a SEM, a TEM, and a STEM, electron beam diffraction, X-ray diffraction (XRD), electron backscattering diffraction (EBSD), or the like. For example, in an orientation mapping image of the EBSD, a bright field image of the electron microscope, and the like, a crystalline portion and an amorphous portion can be visually identified, and the degree of amorphization X and the average crystallite diameter can be measured by analyzing the images. In addition, in a case where spots caused by crystals are not confirmed in the electron beam diffraction, measurement target particles can be specified when the measurement target particles have an amorphous structure.

Note that, the degree of amorphization X (unit: %) is expressed by a relationship of X=(P_A/(P_C+P_A))×100 when a ratio of crystals is set as P_C, and a ratio of an amorphous substance is set as P_A. In a case of calculating the degree of amorphization X by using the XRD, the ratio P_Cof the crystals may be measured as a crystalline scattering integrated intensity I_C, and the ratio P_Aof the amorphous substance may be measured as an amorphous scattering integrated intensity Ia. In a case of calculating the degree of amorphization X by using the EBSD or the electron microscope, P_Cmay be measured as an area ratio of a crystal portion in a grain, and P_Amay be measured as an area ratio of an amorphous portion.

In a case of classifying the large particles 11 by the electron microscope, as described above, structure analysis for specifying a substance state is performed on the large particles 11 included in an observation field of view, but the structure analysis may be performed by arbitrarily selecting some large particles 11 in the observation field of view. In this case, large particles 11 for which the substance state is specified may be regarded as analysis particles, and the other large particles 11 having the same composition as in the analysis particles may be regarded to have the same substance state as in the analysis particles.

For example, Fe—Co—B—P—Si—Cr-based first large particles 11a and Fe—Si—B—Nb—Cu-based second large particles 11b exist as the large particles 11, these can be identified by area analysis using EDX. In addition, for example, structure analysis is performed by selecting any analysis target particle from the Fe—Co—B—P—Si—Cr-based particle group, and when it can be specified that the analysis target particle has an amorphous structure, any of the Fe—Co—B—P—Si—Cr-based particle group can be regarded to have the amorphous structure.

Similarly, structure analysis is performed by selecting any analysis target particle from the Fe—Si—B—Nb—Cu-based particle group, and when it can be specified that the analysis target particle has a nanocrystal structure, any of the Fe—Si—B—Nb—Cu-based particle group can be regarded to have the nanocrystal structure.

Any of the amorphous first large particles 11a and the nanocrystalline second large particles 11b are composed of a soft magnetic alloy, and an alloy composition thereof is not particularly limited. The first large particles 11a and the second large particles 11b have substance states different from each other, but may have the same alloy composition or may have alloy compositions different from each other.

Examples of a soft magnetic alloy having the nanocrystal structure or a soft magnetic alloy having the amorphous structure include an Fe—Si—B-based alloy, an Fe—Si—B—C-based alloy, an Fe—Si—B—C—Cr-based alloy, an Fe—Nb—B-based alloy, an Fe—Nb—B—P-based alloy, an Fe—Nb—B—Si-based alloy, an Fe—Co—P—C-based alloy, an Fe—Co—B-based alloy, an Fe—Co—B—Si-based alloy, an Fe—Si—B—Nb—Cu-based alloy, an Fe—Si—B—Nb—P-based alloy, an Fe—Co—B—P—Si-based alloy, an Fe—Co—B—P—Si—Cr-based alloy, and the like.

A total area ratio occupied by the amorphous first large particles 11a on the cross-section of the magnetic core 2 is set as AL₁, and a ratio of the total area ratio (AL₁) of the first large particles 11a to the total area (A0) of the metal magnetic particles 10 is expressed as AL₁/A0. Similarly, a total area ratio occupied by the nanocrystalline second large particles 11b on the cross-section of the magnetic core 2 is set as AL₂, and a ratio of the total area ratio (AL₂) of the second large particles 11b to the total area ratio (A0) of the metal magnetic particles 10 is expressed as AL₂/A0. Any of AL₁/A0 and AL₂/A0 is not particularly limited, but is preferably 3% or more, more preferably 4% to 78%, and still more preferably 7% to 44%.

In addition, each of AL₁/(AL₁+AL₂) and AL₂/(AL₁+AL₂) is not particularly limited, but may be set, for example, within a range of 4% to 96%. AL₁/(AL₁+AL₂) is more preferably 50% to 96% from the viewpoint of obtaining more excellent DC bias characteristics, and AL₂/(AL₁+AL₂) is more preferably 50% to 90% from the viewpoint of further lowering the core loss.

From the viewpoint of improving the core loss and the DC bias characteristics with balance, and enhancing the effect of improving the core loss, AL₁/(AL₁+AL₂) is preferably 10% to 94%, and more preferably 18% to 85%. Note that, AL₁and AL₂may be measured by a similar manner as in the total area ratio A0 of the metal magnetic particles 10.

In a case where the metal magnetic particles 10 include the small particles 12, a composition of the small particles 12 is not particularly limited. The small particles 12 may have the amorphous structure or the nanocrystal structure, but it is preferable to have the crystalline structure from the viewpoint of a saturation magnetic flux.

Examples of a soft magnetic metal having the crystalline structure include pure iron such as carbonyl iron, Co, an Fe—Ni-based alloy, an Fe—Si-based alloy, an Fe—Si—Cr-based alloy, an Fe—Si—Al-based alloy, an Fe—Si—Al—Ni-based alloy, an Fe—Ni—Si—Co-based alloy, an Fe—Co-based alloy, an Fe—Co—V-based alloy, an Fe—Co—Si-based alloy, an Fe—Co—Si—Al-based alloy, a Co-based alloy, and the like.

Particularly, the small particles 12 are preferably pure iron particles, Fe—Ni-based alloy particles, Fe—Co-based alloy particles, Fe—Si-based alloy particles, or Co particles.

In addition, in a case where the metal magnetic particles 10 include the medium particles 13, a composition of the medium particles 13 is not particularly limited. For example, the medium particles 13 may have the crystalline structure, but it is preferable to have the nanocrystal structure or the amorphous structure from the viewpoint of lowering coercivity.

Note that, the composition of the metal magnetic particles 10 can be analyzed, for example, by using an EDX device or an EPMA attached to an electron microscope. In a case where the first large particles 11a and the second large particles 11b have particle compositions different from each other, the first large particles 11a and the second large particles 11b can be distinguished by area analysis using the EDX device or the EPMA. In addition, the composition of the metal magnetic particles 10 may be analyzed by using a three-dimensional atom probe (3DAP).

In a case of using the 3DAP, an average composition can be measured by setting a small region (for example, a region of @20 nm×100 nm) at the inside of the metal magnetic particles as a measurement target, a composition of a particle main body can be specified by excluding a resin component contained in the magnetic core 2, and an influence due to oxidation of a particle surface or the like.

As shown in FIG. 3A, each of the first large particles 11a includes an insulation coating 4a that covers a particle surface, and each of the second large particles 11b includes an insulation coating 4b that covers a particle surface. Any of the insulation coating 4a and the insulation coating 4b may cover the entirety of the particle surface, or may cover only a part of the particle surface. Each of the insulation coating 4a and the insulation coating 4b preferably covers 80% or more of the particle surface observed on the cross-section of the magnetic core 2.

In addition, any of the insulation coating 4a and the insulation coating 4b may have a deviation in a thickness in a single particle, but it is preferable to have a uniform thickness as can as possible. For example, an arithmetic average height Ra in a contour curve of a coating surface is preferably 0.5 to 100 nm. Ra is a kind of a line roughness parameter. An outermost surface portion of the insulation coating (4a or 4b) observed on the cross-section of the magnetic core 2 may be specified as the contour curve, and Ra may be calculated. For example, when obtaining Ra in any metal particle, the cross-section may be observed and evaluated by a transmission electron microscope. With regard to an evaluation method, when observing the cross-section by the transmission electron microscope, an evaluation may be made by a contour curve of 5 μm or more.

A material of the insulation coating 4a and a material of the insulation coating 4b are not particularly limited, and the insulation coating 4a and the insulation coating 4b may have the same composition or may be compositions different from each other. For example, the insulation coating 4a and the insulation coating 4b may include a coating due to oxidation of the particle surface, and/or a coating containing an inorganic material such as BN, SiO₂, MgO, Al₂O₃, phosphate, silicate, borosilicate, bismuthate, and various kinds of glass.

From the viewpoint of suppressing a decrease in resistivity of the magnetic core 2, any of the insulation coating 4a and the insulation coating 4b preferably includes an oxide glass coating containing one or more kinds of elements selected among P, Si, Bi, and Zn. In the oxide glass coating, when a total amount of elements excluding oxygen among elements contained in the coating is set to 100 wt %, it is preferable that the total amount of one or more kinds of elements selected among P, Si, Bi, and Zn is the greatest, and more preferably 50 wt % or more, and still more preferably 60 wt % or more.

Examples of the oxide glass coating include a phosphate (P₂O₅)-based glass coating, a bismuthate (Bi₂O₃)-based glass coating, a borosilicate (B₂O₃—SiO₂)-based glass coating, and the like.

Examples of the phosphate-based glass include P—Zn—Al—O-based glass, P—Zn—Al—R—O-based glass (“R” is one or more kinds of elements selected from alkali metals), and the like, and 50 wt % or more of P₂O₅is preferably contained in the phosphate-based glass coating.

Examples of the bismuthate-based glass include Bi—Zn—B—Si—O-based glass, Bi—Zn—B—Si—Al—O-based glass, and the like, and 50 wt % or more of Bi₂O₃is preferably contained in the bismuthate-based glass coating.

Examples of the borosilicate-based glass include Ba—Zn—B—Si—Al—O-based glass, and the like, and 10 wt % or more of B₂O₃is preferably contained in the borosilicate-based glass coating.

Any of the insulation coating 4a and the insulation coating 4b may have a single-layer structure or may have a multilayer structure. Examples of the multilayer structure include a stacked structure including an oxide layer of a particle surface and an oxide glass layer that covers the oxide layer. In a case where the insulation coatings 4a and/or 4b have the multilayer structure, a total thickness of respective layers is set as the thickness of the insulation coating. In addition, a composition of the insulation coatings 4a and 4b can be analyzed, for example, by the EDX, the EPMA, or electron energy loss spectroscopy (EELS).

In the magnetic core 2 of this embodiment, the insulation coating 4a of the first large particles 11a is thicker than the insulation coating 4b of the second large particles 11b. When the first large particles 11a having the amorphous structure includes an insulation coating thicker than an insulation coating of the second large particles 11b having the nanocrystal structure, the core loss can be reduced while maintaining good DC bias characteristics.

When an average thickness of the insulation coating 4a of the first large particles 11a is set as T1, and an average thickness of the insulation coating 4b of the second large particles 11b is set as T2, T1/T2 is more than 1.0. From the viewpoint of reducing the core loss, T1/T2 is preferably 1.3 or more, more preferably 1.5 or more, and still more preferably 2.0 or more. An upper limit of T1/T2 is not particularly limited, but from the viewpoint of insulation properties of a powder, T1/T2 is preferably 40 or less, preferably 30 or less, or preferably 20 or less.

In addition, from the viewpoint of the magnetic permeability of the magnetic core, T1 is preferably 200 nm or less. From the viewpoint of reducing the core loss while securing insulation, T2 is preferably 5 nm or more. An upper limit of T2 is determined on the basis of T1, and may be set, for example, to 150 nm or less, 100 nm or less, or 50 nm or less.

T1 may be calculated by observing the cross-section of the magnetic core 2 with various electron microscopes, and it is preferable to calculate T1 by measuring the thickness of the insulation coating 4a with respect to at least 10 first large particles 11a. T2 may be calculated by a similar method as in T1. Note that, large particles 11 which do not include the insulation coating 4 may be contained in the magnetic core 2.

In a case where the metal magnetic particles 10 include the small particles 12, the small particles 12 may not include an insulation coating, but each of the small particles 12 preferably includes an insulation coating 6 that covers a particle surface. A material of the insulation coating 6 is not particularly limited, for example, the insulation coating 6 may be a coating (oxide coating) due to oxidation of a surface of the small particle 12, or a coating containing an inorganic material such as BN, SiO₂, MgO, Al₂O₃, phosphate, silicate, borosilicate, bismuthate, and various kinds of glass, and it is preferable to include an oxide glass coating. In addition, the insulation coating 6 may have a single-layer structure, or may have a structure in which two or more coatings are stacked. An average thickness of the insulation coating 6 is not particularly limited, and for example, the average thickness is preferably 5 to 100 nm, and more preferably 5 to 50 nm.

In a case where the metal magnetic particles 10 include the medium particles 13, the medium particles 13 preferably include an insulation coating that covers a particle surface in a similar manner as in the other particle groups. A composition of the insulation coating of the medium particles 13 is not particularly limited, and may have the same composition as in the insulation coating 4a or 4b of the large particles 11, or may have a composition different from the composition of the insulation coating 4a or 4b of the large particles 11. An average thickness of the insulation coating of the medium particles 13 is not particularly limited, and for example, the average thickness is preferably 5 to 200 nm, and more preferably 10 to 50 nm.

The insulation coating 6 of the small particles 12 and the insulation coating of the medium particles 13 may cover the entirety of the particle surface as in the insulation coating 4 or may cover only a part of the particle surface. Each of the insulation coatings preferably covers 80% or more of the particle surface observed on the cross-section of the magnetic core 2. Note that, the small particles 12 or the medium particles 13 which do not include the insulation coating may be contained in the magnetic core 2.

For example, the resin 20 shown in FIG. 3 functions an insulating binder that fixes the metal magnetic particles 10 in a predetermined dispersed state. A material of the resin 20 is not particularly limited, and the resin 20 preferably includes a thermosetting resin such as an epoxy resin.

Note that, the magnetic core 2 may contain a modifier for suppressing contact between soft magnetic metal particles. As the modifier, polymer materials such as polyethylene glycol (PEG), polypropylene glycol (PPG), and polycaprolactone (PCL) can be used, and polymeric materials having a polycaprolactone structure are preferably used.

Examples of a polymer having the polycaprolactone structure include raw materials of urethane such as polycaprolactone diol and polycaprolactone tetraol, and part of polyesters. The content of the modifier is preferably 0.025 to 0.500 wt % with respect to the total amount of the magnetic core 2. It is considered that the modifier exists in a state of being absorbed to coat the surface of the metal magnetic particles 10. Hereinafter, an example of a method of manufacturing the magnetic core 2 according to this embodiment is described.

First, a raw material powder including the first large particles 11a and a raw material powder including the second large particles 11b are manufactured as a raw material powder of the metal magnetic particles 10. In addition, in a case of adding the small particles 12 or the medium particles 13 to the magnetic core 2, a raw material powder including the small particles 12 and a raw material powder including the medium particles 13 are prepared.

A method of manufacturing each of the raw material powders is not particularly limited, and an appropriate manufacturing method may be used in corresponding to a desired particle composition. For example, the raw material powders may be prepared by an atomization method such as a water atomization method and a gas atomization method. Alternatively, the raw material powders may be prepared by a synthesis method such as a CVD method using at least one or more kinds among evaporation, reduction, and thermal decomposition of metal salts. In addition, the raw material powders may be prepared by using an electrolytic method or a carbonyl method, or may be prepared by pulverizing starting alloys having a ribbon shape or a thin plate. Particularly, a raw material powder including the first large particles 11a and a raw material powder including the second large particles 11b are preferably manufactured by a rapid-cooling gas atomization method.

A particle size of each of the raw material powders can be adjusted by manufacturing conditions of the powders or various classification methods. In addition, a heat treatment for controlling the crystal structure of the second large particles 11b is preferably performed on the raw material powder that becomes the nanocrystalline second large particles 11b.

Note that, in a case where the small particles 12 is set to have the same composition as in the large particles 11 (the first large particles 11a and/or the second large particles 11b), a raw material powder having a wide particle size distribution may be manufactured, and the raw material powder may be classified to obtain a raw material powder including the large particles 11 and a raw material powder including the small particles 12.

Next, a coating forming treatment is performed on each of the raw material powders. In a case of manufacturing the magnetic core by using metal magnetic powders including a plurality of particle groups, typically, a plurality of raw material powders are mixed and then the coating forming treatment is performed at a time on the mixed powder to simplify a manufacturing process. However, when performing the coating forming treatment on the mixed powder, there is a high possibility that insulation coatings of respective particle groups have a similar thickness (that is, T1≈T2).

In this embodiment, in order to make the insulation coating 4a of the first large particles 11a thicker than the insulation coating 4b of the second large particles 11b (that is, to realize a relationship of T1>T2), it is preferable that the coating forming treatment is individually performed on the first large particles 11a and the second large particles 11b.

Examples of a coating forming treatment method include a heat treatment, a phosphate treatment, mechanical alloying, a silane coupling treatment, hydrothermal synthesis, and the like, and an appropriate coating forming treatment may be selected in correspondence with the kind of the insulation coating to be formed.

For example, in a case where the insulation coating 4a and/or the insulation coating 4b include the oxide glass coating, the oxide glass coating is preferably formed by a mechano-chemical method using a mechano-fusion device. Specifically, in a coating forming treatment by the mechano-chemical method, a raw material powder including large particles, and a powder-shaped coating material including a constituent element of an insulation coating are introduced into a rotary rotor of the mechano-fusion device, and the rotary rotor is caused to rotate.

A press head is provided inside the rotary rotor, and when the rotary rotor is caused to rotate, a mixture of the raw material powder and the coating material is compressed in a gap between an inner wall surface of the rotary rotor and the press head, and friction heat occurs. Due to the friction heat, the coating material is softened, and is fixed to a surface of the large particles due to a compression operation, and the oxide glass coating is formed.

Note that, the thickness of the insulation coating 4a and the thickness of the insulation coating 4b may be controlled on the basis of a mixing ratio of the coating material, a rotation speed, treatment time, and the like.

In a case of forming the insulation coating 6 with respect to the small particles 12, it is preferable to form the insulation coating 6 by mixing a raw material powder including the small particles 12 and a powder-shaped coating material including a constituent element of the insulation coating 6 while applying mechanical impact energy to the resultant mixture, and it is more preferable to form the insulation coating 6 by mixing the raw material powder and the coating material while applying impact, compression, and shear energy to the resultant mixture.

In the coating forming treatment, as a device capable of applying mechanical energy to a powder, a powder treatment device such as a planetary ball mill and Nobilta manufactured by HOSOKAWA MICRON CORPORATION can be used. For example, in a coating forming treatment performed on the small particles 12, a powder treatment device 60 capable of performing mixing at a high rotation speed as shown in FIG. 4 can be used.

The powder treatment device 60 has a cylindrical cross-section and includes a chamber 61 in which a rotatable blade 62 is provided inside the chamber 61. A raw material powder including the small particles 12 and a coating material are put into the chamber 61, and the blade 62 is caused to rotate at a rotational speed of 2000 to 6000 rpm, thereby applying mechanical impact, compression, and shear energy to a mixture 63 of the raw material powder and the coating material. When using the powder treatment device 60, particularly, even in the small particles 12 having a small particle size, the insulation coating 6 can be formed on the particle surface.

In a case of using the medium particles 13 including an insulation coating, the medium particles 13 may be mixed with the first large particles 11a or the second large particles 11b and may be subjected to the coating forming treatment in combination with the first large particles 11a or the second large particles 11b to form the insulation coating on surfaces of the medium particles 13. Alternatively, the coating forming treatment may be individually performed on only the raw material powder of the medium particles 13.

Hereinafter, a method of manufacturing the magnetic core 2 by using respective raw material powders of the metal magnetic particle 10 is described. First, respective raw material powders on which the insulation coating is formed and a resin raw material (thermosetting resin or the like) are kneaded to obtain a resin compound. In the kneading process, various kneaders such as a kneader, a planetary mixer, a rotation/revolution mixer, and a twin-screw extruder may be used, and a modifier, a preservative, a dispersant, a non-magnetic powder, or the like may be added to the resin compound.

Next, the resin compound is filled in a press mold and compression molding is performed to obtain a green compact. A molding pressure at this time is not particularly limited, and is preferably set to, for example, 1250 to 2000 MPa. Note that, a total area ratio of the metal magnetic particles 10 in the magnetic core 2 can be controlled by an addition amount of the resin 20, but can also be controlled by the molding pressure. In a case of using the thermosetting resin as the resin 20, the green compact is maintained at 100° C. to 200° C. for 1 to 5 hours to harden the thermosetting resin. The magnetic core 2 shown in FIG. 1 is obtained by the above-described processes.

Although not particularly limited, for example, the magnetic core 2 according to this embodiment is applicable to various magnetic components such as an inductor, a choke coil, a transformer, and a reactor. For example, a magnetic component 100 shown in FIG. 5 is an example of a magnetic component including the magnetic core 2.

In the magnetic component 100 shown in FIG. 5, an element body is constituted by the magnetic core 2 shown in FIG. 1. A coil 5 is embedded inside the magnetic core 2 that is the element body, and end portions 5a and 5b of the coil 5 are respectively drawn to end surfaces of the magnetic core 2. In addition, a pair of external electrodes 7 and 9 are respectively formed on the end surfaces of the magnetic core 2, and the pair of external electrodes 7 and 9 are respectively electrically connected to the end portions 5a and 5b of the coil 5. Note that, in a case where the coil 5 is embedded inside the magnetic core 2 as in the magnetic component 100, it is assumed that the area ratios of the metal magnetic particles 10 such as A0, AL (AL) and AL₂), and AS are analyzed in fields of view where the coil 5 does not come into sight.

The magnetic component including the magnetic core 2 is not limited to an aspect as shown in FIG. 5, and may be a magnetic component obtained by winding a wire around the surface of the magnetic core having a predetermined shape (for example, a ring shape or a drum shape) in a predetermined number of turns. The application of the magnetic component that is not limited to the magnetic component 100 shown in FIG. 5 is not particularly limited, but examples thereof include magnetic components (for example, a choke coil, a reactor, and the like) for applications with a low frequency of approximately 400 kHz or less, and particularly, in a case of the low-frequency applications, the effect of reducing the core loss is large. Note that, the magnetic component is not limited to the magnetic component including the magnetic core, and may be a magnetic component that is not provided with the magnetic core.

(Summary of First Embodiment)

The magnetic core 2 of this embodiment contains the metal magnetic particles 10 and the resin 20, and the total area ratio A0 of the metal magnetic particles 10 appear on the cross-section of the magnetic core 2 is 75% or more. The metal magnetic particles 10 include the first large particles 11a having the amorphous structure, and the second large particles 11b having the nanocrystal structure, and the insulation coating 4a of the first large particles 11a is thicker than the insulation coating 4b of the second large particles 11b.

Since the magnetic core 2 has the above-described characteristics, the core loss can be reduced while maintaining good DC bias characteristics. Specifically, the following facts have been clarified by experiments conducted by the present inventors.

When comparing a magnetic core containing particles having the nanocrystal structure as a main powder (hereinafter, such magnetic core may be referred to as a nanocrystalline magnetic core), and a magnetic core containing particles having the amorphous structure as a main powder (hereinafter, such magnetic core may be referred to as an amorphous magnetic core) with each other, the core loess is lower in the nanocrystalline magnetic core in comparison to the amorphous magnetic core, and the DC bias characteristics are more excellent in the amorphous magnetic core in comparison to the nanocrystalline magnetic core. However, when simply mixing the particles having the amorphous structure and the particles having the nanocrystal structure, the core loss can only be obtained as a value calculated from the mixing ratio.

In the magnetic core 2 of this embodiment, the first large particles 11a which include the relatively thick insulation coating 4a and have the amorphous structure, and the second large particles 11b which include the relatively thin insulation coating 4b and have the nanocrystal structure are mixed. In the magnetic core 2 of this embodiment, the core loss can be effectively reduced while maintaining the DC bias characteristics in a satisfactory manner.

In addition, in this embodiment, even though high-pressure molding of the magnetic powder is performed in order to increase Bs of the magnetic core 2, since the insulation coating 4a of the first large particles 11a having the amorphous structure is made to be thicker than the insulation coating 4b of the second large particles 11b having the nanocrystal structure, the core loss can be further reduced while securing high magnetic permeability (for example, magnetic permeability of 20 or more, 25 or more, 30 or more, or 35 or more).

Second Embodiment

In a second embodiment, a magnetic core 2a shown in FIG. 3B is described. Note that, in the second embodiment, description of a configuration common to the first embodiment is omitted, and the same reference number as in the first embodiment is used.

As shown in FIG. 3B, in the magnetic core 2a of the second embodiment, the first large particles 11a having the amorphous structure, and the second large particles 11b having the nanocrystal structure are mixed, and the insulation coating 4a of the first large particles 11a is thicker than the insulation coating 4b of the second large particles 11b. Accordingly, even in the magnetic core 2a of the second embodiment, a similar operational effect as in the magnetic core 2 of the first embodiment is obtained.

Two or more kinds of small particles 12 different in a composition of the insulation coating 6 are contained in the magnetic core 2a. In other words, the small particles 12 included in the metal magnetic particles 10 can be subdivided into two or more kinds of small particle groups on the basis of a coating composition. Specifically, the small particles 12 include at least first small particles 12a including a first insulation coating 6a and second small particles 12b including a second insulation coating 6b having a composition different from a composition of the first insulation coating 6a, and may further include third small particles 12c to n^thsmall particles 12x having a coating composition different from that of the other small particle groups. n represents the number of small particle groups in a case of subdividing the small particles 12 on the basis of the coating composition, and an upper limit of n is not particularly limited. From the viewpoint of simplifying manufacturing processes, n is preferably 4 or less.

Here, “different in a coating composition” represents that the kinds of constituent elements contained in the insulation coating 6 are different from each other, and the constituent elements of the insulation coating 6 represent elements contained in the insulation coating 6 by 1 at % or more when a total content ratio of elements other than oxygen and carbon among elements contained in the insulation coating 6 is set to 100 at %. The composition of the insulation coating 6 may be analyzed by area analysis or point analysis using the EDX device or the EPMA.

A material of the insulation coatings 6 (the first insulation coating 6a, the second insulation coating 6b, and the third insulation coating 6c to the n^thinsulation coating 6x) included in the small particles 12 is not particularly limited. For example, each of the insulation coatings 6 may be set as a coating (oxide coating) due to oxidation of surfaces of the small particles 12, or a coating containing an inorganic material such as BN, SiO₂, MgO, Al₂O₃, phosphate, silicate, borosilicate, bismuthate, and various kinds of glass. It is preferable that the insulation coating 6 includes an oxide glass coating. Examples of the oxide glass include silicate (SiO₂)-based glass, phosphate (P₂O₅)-based glass, bismuthate (Bi₂O₃)-based glass, borosilicate (B₂O₃—SiO₂)-based glass, and the like. The first insulation coating 6a and the second insulation coating 6b may have compositions different from each other, and a combination of coating compositions is not particularly limited. For example, as a combination of the first insulation coating 6a and the second insulation coating 6b, a combination of a P—O-based glass coating and a P—Zn—Al—O-based glass coating, a combination of a Bi—Zn—B—Si—O-based glass coating and an Si—O-based glass coating, or a combination of a Ba—Zn—B—Si—Al—O-based glass coating and an Si—O-based glass coating is preferable, and the combination of the Ba—Zn—B—Si—Al—O-based glass coating and the Si—O-based glass coating is more preferable.

Even in a case where the small particles 12 include the third small particles 12c to the n^thsmall particles 12x in addition to the first small particles 12a and the second small particles 12b, the combination of the coating compositions is not particularly limited, and the third small particles 12c to the n^thsmall particles 12x may include the oxide glass coating having a composition different from compositions of the other small particle groups.

The average thickness of the insulation coating 6 is not particularly limited, and for example, the average thickness is preferably 5 to 100 nm, and more preferably 5 to 50 nm. The first insulation coating 6a to the n^thinsulation coating 6x may have a similar average thickness or may have average thicknesses different from each other.

Note that, the insulation coating 6 such as the first insulation coating 6a and the second insulation coating 6b may have a stacked structure in which a plurality of coating layers are stacked. For example, the insulation coating 6 may have a stacked structure including an oxide layer of a particle surface, and an oxide glass layer that covers the oxide layer. In a case where one or more kinds of the insulation coatings 6 among the first insulation coating 6a to the n^thinsulation coating 6x has the stacked structure, a composition of an outermost layer (a coating layer located on the most surface side) may be different among the first insulation coating 6a to the n^thinsulation coating 6x, and compositions of the other coating layers located between the outermost layer and the particle surface may match each other or may be different from each other among the first insulation coating 6a to the n^thinsulation coating 6x.

In addition, any of the first small particles 12a to the n^thsmall particles 12x may have the same particle composition or may have particle compositions different from each other. A substance state of the first small particles 12a to the n^thsmall particles 12x is not particularly limited, and one or more kinds of small particle groups among the first small particles 12a to the n^thsmall particles 12x may be amorphous or nanocrystals, but as described above, any of the first small particles 12a to the n^thsmall particles 12x is preferably crystalline.

Total area ratios occupied by the first small particles 12a to the n^thsmall particles 12x on the cross-section of the magnetic core 2a are set as AS₁to AS_n. In this case, a total area ratio AS occupied by the small particles 12 on the cross-section of the magnetic core 2a can be expressed as the sum of AS₁to AS_n. In addition, ratios of the total area ratios of respective small particle groups to the total area ratio AS of the small particles 12 can be expressed as AS₁/AS to AS₁/AS. Any of AS₁/AS to AS₁/AS is preferably 1% or more, more preferably 6% or more, and still more preferably 10% or more.

When manufacturing the magnetic core 2a, the coating forming treatment is individually formed on each of the small particle groups (first small particles 12a to the n^thsmall particles 12x), and in the coating forming treatment on each of the small particle groups, the powder treatment device 60 as shown in FIG. 4 is preferably used as described in the first embodiment. In addition, the composition of the respective insulation coatings 6 (the first insulation coating 6a, the second insulation coating 6b, and the third insulation coating 6c to the n^thinsulation coating 6x) may be controlled by a kind or a composition of a coating material that is mixed with a raw material powder. Note that, manufacturing conditions except for the above-described conditions may be set to be similar as in the first embodiment.

(Summary of Second Embodiment)

In the magnetic core 2a of the second embodiment, the second particle group 10b in which the Heywood diameter is less than 3 μm includes two or more kinds of small particles 12 (the first small particles 12a, the second small particles 12b, and the like) different in a coating composition.

As described above, when the metal magnetic particles 10 include two or more kinds of small particles 12 different in a coating composition, it is considered that when being kneaded with a resin, an electrical repulsive force between the metal magnetic particles is improved, and magnetic aggregation of the metal magnetic particles 10 is suppressed. As a result, in the magnetic core 2a, the DC bias characteristics can be further improved.

Note that, the present invention is not limited to the above-described embodiments, and the above-described embodiments can also be combined, and various modifications can be made within the scope of the present invention.

For example, the structure of the magnetic component is not limited to the aspect shown in FIG. 5, and a magnetic component may be manufactured by combining a plurality of the magnetic cores 2. In addition, the method of manufacturing the magnetic core is not limited to the manufacturing method illustrated in the above-described embodiments, and the magnetic core 2 and the magnetic core 2a may be manufactured by a sheet method or injection molding, or may be manufactured by two-stage compression. In the manufacturing method using the two-stage compression, for example, a plurality of preliminary molded bodies are prepared by temporarily compressing a resin compound, and a magnetic core may be obtained by combining the preliminary molded bodies and by subjecting the resultant combined preliminary molded bodies to main compression.

In addition, the magnetic component is not limited to a magnetic component including the magnetic core, and may be a magnetic component that is not provided with the magnetic core. That is, a composite of a resin and a metal powder may be defined as the magnetic core. For example, a magnetic sheet is exemplified.

EXAMPLES

Hereinafter, the present invention is described in more detail with reference to specific examples. However, the present disclosure is not limited to the following examples.

(Experiment 1)

In Experiment 1, amorphous magnetic core samples (Sample Nos. 1 to 6) and nanocrystalline magnetic core samples (Sample Nos. 7 to 12) were manufactured by using metal magnetic particles obtained by mixing one kind of large particles and one kind of small particles. Note that, the magnetic cores of Sample Nos. 1 to 12 shown in Experiment 1 correspond to comparative examples.

As a raw material powder of the metal magnetic particles, a large-diameter powder having the amorphous structure, a large-diameter powder having the nanocrystal structure, and a small-diameter powder composed of small particles of pure ion were prepared. The large-diameter powder having the amorphous structure is an Fe—Co—B—P—Si—Cr-based alloy powder and was manufactured by a rapid-cooling gas atomization method. An average particle size of the Fe—Co—B—P—Si—Cr-based alloy powder was 20 μm, and the degree of amorphization was 85% or more.

The large-diameter powder having the nanocrystal structure is an Fe—Si—B—Nb—Cu-based alloy powder and was manufactured by performing a heat treatment on a powder obtained by the rapid-cooling gas atomization method. An average particle size of the Fe—Si—B—Nb—Cu-based alloy powder was 20 μm, the degree of amorphization was less than 85%, and an average crystallite diameter was within a range of 0.5 to 30 nm. In addition, an average particle size of the pure iron powder that is the small-diameter powder was 1 μm.

In Sample Nos. 1 to 6 in Experiment 1, the coating forming treatment using the mechano-fusion device was performed on the large-diameter powder having the amorphous structure to form an insulation coating of P—Zn—Al—O-based oxide glass on surfaces of large particles. On the other hand, in Sample Nos. 7 to 12 in Experiment 1, the coating forming treatment using the mechano-fusion device was performed on the large-diameter powder having the nanocrystal structure to form an insulation coating of P—Zn—Al—O-based oxide glass on surfaces of large particles. Note that, in the coating forming treatment, an addition amount of the coating material was controlled so that an average thickness of the insulation coating becomes values shown in Table 1.

The coating forming treatment was performed on the small-diameter powder used in Experiment 1 by using the powder treatment device (Nobilta, manufactured by HOSOKAWA MICRON CORPORATION) as shown in FIG. 4 to form an insulation coating of Ba—Zn—B—Si—Al—O-based oxide glass on surfaces of small particles. An average thickness of the insulation coatings formed on the small particles was within a range of 15±10 nm in any sample.

Next, raw material powders (a large-diameter powder and a small-diameter powder) of the metal magnetic particles, and an epoxy resin were kneaded to obtain a resin compound. More specifically, in Sample Nos. 1 to 6, large particles having the amorphous structure and small particles were mixed to obtain a resin compound. On the other hand, in Sample Nos. 7 to 12, large particles having the nanocrystal structure and small particles were mixed to obtain a resin compound. Note that, an addition amount of the epoxy resin (the amount of the resin) in the resin compound was set to 2.5 parts by mass with respect to 100 parts by mass of metal magnetic particles in any sample in Experiment 1. In addition, the large-diameter powder and the small-diameter powder were mixed so that an area ratio satisfies a relationship of “large particles:small particles=approximately 8:2” in any sample in Experiment 1.

Next, the resin compound was filled in a press mold and was pressurized to obtain a green compact having a toroidal shape. A molding pressure at this time was controlled so that magnetic permeability (relative magnetic permeability) of the magnetic core becomes 35. Then, the green compact was subjected to a heating treatment at 180° C. for 60 minutes to harden the epoxy resin inside the green compact, thereby obtaining a magnetic core having a toroidal shape (an external shape of 11 mm, an inner diameter of 6.5 mm, and a thickness of 2.5 mm).

In the respective samples in Experiment 1, the following evaluation was made on the prepared magnetic cores.

Cross-Section Observation of Magnetic Core

A cross-section of each of the magnetic cores was observed with a SEM to calculate a ratio of a total area of the metal magnetic particles (the total area ratio A0 of the metal magnetic particles) to a total area (1000000 μm²) of an observation field of view. The total area ratio A0 of the metal magnetic particles was within a range of 80±2% in any of the respective samples in Experiment 1.

In addition, at the time of the SEM observation, the Heywood diameter of each of the metal magnetic particles was measured, and area analysis with the EDX was performed to specify a composition system of the metal magnetic particles, and the metal magnetic particles observed on the cross-section of the magnetic core were classified into large particles and small particles. In the respective samples in Experiment 1, D20 of the large particles was 3 μm or more, an average particle size (an arithmetic average value of the Heywood diameter) of the large particles was within a range of 10 to 30 μm, D80 of the small particles was less than 3 μm, and an average particle size of the small particles was within a range of 0.5 to 1.5 μm. In addition, a total area of the large particles included in the observation field of view and a total area of the small particles included in the observation field of view were measured, and a ratio (AL/A0) of the total area of the large particles to the total area of the metal magnetic particles, and a ratio (AS/A0) of the total area of the small particles to the total area of the metal magnetic particles were calculated.

In addition, in the SEM observation, the thickness of the insulation coating of each of the large particles existing in the observation field of view was measured, and an average thickness thereof was calculated.

Evaluation of Magnetic Permeability and DC Bias Characteristics

In evaluation of the magnetic permeability and the DC bias characteristics, first, a polyurethane copper wire (UEW wire) was wound around the magnetic core having a toroidal shape. Then, an inductance of the magnetic core at a frequency of 20 kHz was measured by using an LCR meter (4284A, manufactured by Agilent Technologies Japan, Ltd.) and a DC bias power supply (42841A, manufactured by Agilent Technologies Japan, Ltd.). More specifically, an inductance under a condition (0 kA/m) in which a DC magnetic field is not applied, and an inductance under a condition in which a DC magnetic field of 8 kA/m is applied were measured, and μ0 (magnetic permeability at 0 A/m) and μHdc (magnetic permeability at 8 kA/m) were calculated from the inductances.

The DC bias characteristics were evaluated on the basis of a variation rate of the magnetic permeability when applying the DC magnetic field. That is, the variation rate (unit: %) of the magnetic permeability is expressed as (μ0−μHdc)/μ0, and as the variation rate of the magnetic permeability is smaller, the DC bias characteristics can be determined as being good.

Evaluation of Core Loss

A core loss (unit: kW/m³) of each of the magnetic cores was measured by using a BH analyzer (SY-8218, manufactured by IWATSU ELECTRIC CO., LTD.). A magnetic flux density when measuring the core loss was set to 200 mT, and a frequency was set to 20 KHz.

Overall Evaluation of Experiment 1

Evaluation results of Experiment 1 are shown in Table 1A.

TABLE 1A

Magnetic

Large particles

Area ratio (%)
permeability
DC bias
Core loss

Example/

Coating

First large
Small
Measured
characteristics
Measured

Sample
Comparative

Coating
thickness
Small
particles
particles
value
Measured value
value

No.
Example
Structure
composition
(nm)
particles
AL/A0
AS/A0
(μ0)
(Variation rate)
(kW/m³)

1
Comparative
Amorphous
P—Zn—Al—O-based
5
Fe
78.7
21.3
35.0
7.5%
900

Example

2
Comparative
Amorphous
P—Zn—Al—O-based
15
Fe
80.8
19.2
35.3
8.3%
910

Example

3
Comparative
Amorphous
P—Zn—Al—O-based
50
Fe
78.7
21.3
34.7
8.4%
920

Example

4
Comparative
Amorphous
P—Zn—Al—O-based
100
Fe
80.8
19.2
35.4
8.5%
940

Example

5
Comparative
Amorphous
P—Zn—Al—O-based
150
Fe
80.2
19.8
35.2
8.6%
980

Example

6
Comparative
Amorphous
P—Zn—Al—O-based
200
Fe
79.9
20.1
35.3
8.7%
990

Example

7
Comparative
Nanocrystal
P—Zn—Al—O-based
5
Fe
79.6
20.4
35.0
22.3%
350

Example

8
Comparative
Nanocrystal
P—Zn—Al—O-based
15
Fe
79.8
20.2
34.5
21.2%
380

Example

9
Comparative
Nanocrystal
P—Zn—Al—O-based
50
Fe
79.7
20.3
35.4
23.2%
380

Example

10
Comparative
Nanocrystal
P—Zn—Al—O-based
100
Fe
80.5
19.5
34.6
21.4%
390

Example

11
Comparative
Nanocrystal
P—Zn—Al—O-based
150
Fe
80.2
19.8
35.0
22.3%
400

Example

12
Comparative
Nanocrystal
P—Zn—Al—O-based
200
Fe
80.1
19.9
35.0
22.3%
420

Example

As shown in Table 1A, in the magnetic cores (amorphous magnetic cores) of Sample Nos. 1 to 6 in which the large particles having the amorphous structure are set as a main powder, the DC bias characteristics were better but the core loss tended to be higher in comparison to the magnetic cores (nanocrystalline magnetic cores) of Sample Nos. 7 to 12 in which the large particles having the nanocrystal structure are set as a main powder. On the contrary, in the nanocrystalline magnetic cores of Sample Nos. 7 to 12, the core loss was lower but the DC bias characteristics tended to be inferior in comparison to the amorphous magnetic cores.

Note that, it could be understood that in both the nanocrystalline magnetic cores and the amorphous magnetic cores, when the insulation coating provided in the large particles is made to be thicker, the core loss tends to increase. From the results, it could be understood that it is not easy to make a low core loss and good DC bias characteristics be compatible with each other in a case where the main powder of the magnetic cores is composed of only one kind of large particles.

(Experiment 2)

In Experiment 2, as shown in Table 1B and Table 1C, magnetic cores were manufactured by using metal magnetic particles obtained by mixing first large particles having the amorphous structure and second large particles having the nanocrystal structure.

Even in Experiment 2, as a raw material powder of the metal magnetic particles, an Fe—Co—B—P—Si—Cr-based alloy powder (first large particles having the amorphous structure) and an Fe—Si—B—Nb—Cu-based alloy powder (second large particles having the nanocrystalline structure) which have the same specification as in Experiment 1, and a pure iron powder (small particles) were prepared.

Next, an insulation coating of P—Zn—Al—O-based oxide glass was formed on surfaces of the particles of the Fe—Co—B—P—Si—Cr-based alloy powder by using a mechano-fusion device. At this time, the thickness of the insulation coating was adjusted by controlling an addition amount of a coating material and treatment time, thereby obtaining six kinds of first large particles different in the average thickness T1. Similarly, the coating forming treatment using the mechano-fusion device was performed on the Fe—Si—B—Nb—Cu-based alloy powder (an insulation coating of P—Zn—Al—O-based oxide glass was formed), thereby obtaining six kinds of second large particles different in the average thickness T2. In addition, the coating forming treatment was performed on the pure iron powder by using the powder treatment device as shown in FIG. 4 to form an insulation coating of Ba—Zn—B—Si—Al—O-based oxide glass on surfaces of the small particles. An average thickness of the insulation coating of the small particles was within a range of 15±10 nm.

Next, the first large particles having the amorphous structure, the second large particles having the nanocrystal structure, the small particles, and an epoxy resin were kneaded to obtain a resin compound. At this time, the large particles and the small particles were mixed so that an area ratio satisfies a relationship of “first large particles:second large particles:small particles=4:4:2” in any sample in Experiment 2. In addition, an addition amount of the epoxy resin (the amount of the resin) in the resin compound was set to 2.5 parts by mass with respect to 100 parts by mass of metal magnetic particles in any sample in Experiment 2.

Next, the resin compound was filled in a press mold and was pressurized to obtain a green compact having a toroidal shape. A molding pressure at this time was controlled so that magnetic permeability (μ0) of the magnetic core becomes 35. Then, the green compact was subjected to a heating treatment at 180° C. for 60 minutes to harden the epoxy resin inside the green compact, thereby obtaining a magnetic core having a toroidal shape (an external shape of 11 mm, an inner diameter of 6.5 mm, and a thickness of 2.5 mm).

Even in Experiment 2, similar evaluation (cross-section observation of the magnetic cores, and measurement of the magnetic permeability, the DC bias characteristics, and the core loss) as in Experiment 1 was performed. In cross-section observation of the magnetic core, in any sample, it was confirmed that D20 of the first large particles and the second large particles was 3 μm or more, an average particle size of the first large particles and the second large particles was within a range of 10 to 30 μm, D80 of the small particles was less than 3 μm, and an average particle size of the small particles was within a range of 0.5 to 1.5 μm.

In addition, an average thickness T1 of the insulation coating provided in the first large particles having the amorphous structure, an average thickness T2 of the insulation coating provided in the second large particles having the nanocrystal structure, and ratios (AL₁/A0, AL₂/A0, AS/A0) of total areas of respective particle groups to a total area of the metal magnetic particles become results shown in Table 1B and Table 1C. Note that, the total area ratio A0 of the metal magnetic particles was within a range of 80±2% in any of the samples in Experiment 2.

In Experiment 2, an expected value of the core loss (a calculated value of the core loss which is calculated from the mixing ratio) was calculated on the basis of the mixing ratio of the first large particles and the second large particles, and the improvement rate of the core loss in each sample was obtained with the expected value set as a reference. For example, the expected value of the core loss in Sample No. 13 was calculated by the following expression.

Expected value=[(β₁/α₁)×C₁]+[(β₂/α₇)×C₇]

α₁: Ratio (AL/A0) of amorphous large particles in Sample No. 1

C₁: Core loss of Sample No. 1

- α₇: Ratio (AL/A0) of nanocrystalline large particles in Sample No. 7

C₇: Core loss of Sample No. 7

β₁: Ratio (AL₁/A0) of amorphous large particles in Sample No. 13

β₂: Ratio (AL₂/A0) of nanocrystalline large particles in Sample No. 13

As described above, when calculating the expected value (calculated value), characteristic values of the magnetic cores (Sample Nos. 1 to 12) containing large particles having the same specifications (a particle composition, a coating composition, and an average thickness) as in the large particles used in the respective samples (Sample Nos. 13 to 48) were used with reference to Table 1A.

After calculating the expected value of the core loss by the above-described method, an improvement rate [(expected value−measured value)/expected value] between the expected value and an actually measured core loss was calculated. As the “improvement rate” is larger, the core loss is further reduced. In this experiment, when the improvement rate was 5% or more, preferably 10% or more, and more preferably 15% or more, determination was made as good. Results are shown in Table 1B and Table 1C.

In addition, with regard to the DC bias characteristics, in addition to a measured value, an improvement rate from an expected value (calculated value) was obtained by calculation as in the core loss. Results are shown in Table 1B and Table 1C. With regard to the DC bias characteristics, samples in which the improvement rate was −1% or more were determined as being equivalent to the cores shown in Table 1A or good.

TABLE 1B

Nanocrystalline

Amorphous first
second large

Area ratio (%)

Example/
large particles
particles

First large
Second large
Small

Sample
Comparative
Coating thickness
Coating thickness

particles
particles
particles

No.
Example
T1 (nm)
T2 (nm)
T1/T2
AL₁/A0
AL₂/A0
AS/A0

13
Comparative
5
5
1.0
40.8
40.6
18.6

Example

14
Comparative
5
15
0.3
40.4
40.7
18.9

Example

15
Comparative
5
50
0.1
40.3
40.0
19.7

Example

16
Comparative
5
100
0.1
41.4
39.9
18.7

Example

17
Comparative
5
150
0.0
39.3
39.3
21.4

Example

18
Comparative
5
200
0.0
41.3
39.1
19.6

Example

19
Example
15
5
3.0
40.3
39.7
20.0

20
Comparative
15
15
1.0
40.4
40.7
18.9

Example

21
Comparative
15
50
0.3
40.6
40.5
18.9

Example

22
Comparative
15
100
0.2
41.0
40.9
18.1

Example

23
Comparative
15
150
0.1
39.3
41.0
19.7

Example

24
Comparative
15
200
0.1
40.2
38.9
20.9

Example

25
Example
50
5
10.0
38.6
39.0
22.4

26
Example
50
15
3.3
40.9
40.9
18.2

27
Comparative
50
50
1.0
39.3
41.4
19.3

Example

28
Comparative
50
100
0.5
41.0
40.9
18.1

Example

29
Comparative
50
150
0.3
40.7
39.7
19.6

Example

30
Comparative
50
200
0.3
38.8
41.5
19.7

Example

Magnetic

permeability

Core loss

Measured
DC bias characteristics
Measured

Sample
value
Measured value
Calculated
Improvement
value
Calculated
Improvement

No.
(μ0)
(Variation rate)
value
rate
(kW/m³)
value
rate

13
34.9
14.4%
15.3%
0.9%
630
645
2.4%

14
35.3
13.6%
14.7%
1.1%
660
656
−0.6%

15
34.6
13.6%
15.5%
1.9%
680
652
−4.3%

16
35.2
13.3%
14.6%
1.3%
640
667
4.0%

17
35.1
13.3%
14.7%
1.4%
630
646
2.4%

18
34.6
13.5%
14.8%
1.3%
660
677
2.6%

19
35.4
14.9%
15.3%
0.4%
500
628
20.4%

20
35.4
14.8%
14.9%
0.1%
650
649
−0.2%

21
34.9
14.8%
15.9%
1.1%
660
650
−1.5%

22
34.5
14.0%
15.1%
1.1%
690
660
−4.6%

23
35.3
13.8%
15.4%
1.6%
700
647
−8.2%

24
34.6
14.5%
15.0%
0.5%
790
657
−20.3%

25
35.1
15.2%
15.0%
−0.2%
500
623
19.7%

26
35.3
14.8%
15.2%
0.4%
520
673
22.7%

27
35.2
14.3%
16.2%
1.9%
650
657
1.1%

28
35.1
13.8%
15.2%
1.4%
700
678
−3.3%

29
34.5
13.5%
15.4%
1.9%
720
674
−6.8%

30
34.6
14.4%
15.7%
1.3%
780
671
−16.2%

TABLE 1C

Nanocrystalline

Amorphous first
second large

Area ratio (%)

Example/
large particles
particles

First large
Second large
Small

Sample
Comparative
Coating thickness
Coating thickness

particles
particles
particles

No.
Example
T1 (nm)
T2 (nm)
T1/T2
AL₁/A0
AL₂/A0
AS/A0

31
Example
100
5
20.0
39.6
41.3
19.1

32
Example
100
15
6.7
40.3
39.1
20.6

33
Example
100
50
2.0
38.6
40.8
20.6

34
Comparative
100
100
1.0
39.9
39.5
20.6

Example

35
Comparative
100
150
0.7
39.2
39.6
21.2

Example

36
Comparative
100
200
0.5
38.7
39.3
22.0

Example

37
Example
150
5
30.0
38.8
40.2
21.0

38
Example
150
15
10.0
41.1
41.2
17.7

39
Example
150
50
3.0
38.8
39.3
21.9

40
Example
150
100
1.5
40.9
38.7
20.4

41
Comparative
150
150
1.0
39.6
41.4
19.0

Example

42
Comparative
150
200
0.8
41.3
40.2
18.5

Example

43
Example
200
5
40.0
39.4
40.7
19.9

44
Example
200
15
13.3
39.7
40.0
20.3

45
Example
200
50
4.0
41.0
39.2
19.8

46
Example
200
100
2.0
39.6
40.7
19.7

47
Example
200
150
1.3
40.7
39.5
19.8

48
Comparative
200
200
1.0
39.5
40.3
20.2

Example

Magnetic
DC bias characteristics

permeability
Measured

Core loss

Measured
value

Measured

Sample
value
(Variation
Calculated
Improvement
value
Calculated
Improvement

No.
(m0)
rate)
value
rate
(kW/m³)
value
rate

31
35.2
15.3%
15.7%
0.4%
510
643
20.6%

32
34.6
14.7%
14.6%
−0.1%
520
655
20.6%

33
34.8
16.1%
15.9%
−0.2%
530
644
17.7%

34
34.9
13.8%
14.7%
0.9%
660
656
−0.6%

35
34.8
14.0%
15.1%
1.1%
680
654
−4.0%

36
34.6
14.2%
15.0%
0.8%
800
657
−21.8%

37
34.6
15.0%
15.3%
0.3%
490
651
24.7%

38
35.0
14.9%
15.3%
0.4%
520
698
25.5%

39
35.0
16.2%
15.5%
−0.7%
560
662
15.4%

40
35.4
14.3%
14.6%
0.3%
580
687
15.6%

41
35.1
14.4%
15.7%
1.3%
700
690
−1.4%

42
34.5
14.2%
15.5%
1.3%
780
715
−9.0%

43
35.2
15.0%
15.7%
0.7%
490
667
26.6%

44
34.9
14.8%
14.9%
0.1%
540
682
20.9%

45
35.3
16.1%
15.9%
−0.2%
570
695
18.0%

46
35.4
14.8%
15.1%
0.3%
580
688
15.7%

47
35.5
15.4%
15.4%
0.0%
590
701
15.9%

48
35.3
15.5%
15.5%
0.0%
700
701
0.1%

As shown in Table 1B and Table 1C, in the respective samples in Experiment 2, the core loss could be further lowered in comparison to the amorphous magnetic cores (Sample Nos. 1 to 6). In addition, in comparative examples in which T1/T2 is 1.0 or less, the core loss was equivalent to the expected value calculated from the mixing ratio, or was worse than the expected value. On the contrary, in examples in which T1/T2 is more than 1.0, the core loss was lowered from the expected value (calculated value) by 15% or more. Note that, with regard to the DC bias characteristics, in the examples (T1/T2 is more than 1.0) and the comparative examples (T1/T2 is 1.0 or less), no significant difference was recognized in the improvement rate, and the DC bias characteristics were further improved in comparison to the nanocrystalline magnetic cores (Sample Nos. 7 to 12) in any of the examples and the comparative examples.

As described above, when mixing the first large particles which include the relatively thick insulation coating and have the amorphous structure, and the second large particles which include the relatively thin insulation coating and have the nanocrystal structure, it could be confirmed that the core loss could be reduced while maintaining good DC bias characteristics. Particularly, in magnetic cores (examples) satisfying a relationship of T1>T2, it could be confirmed that T1/T2 is preferably 1.3 or more from the viewpoint of reducing the core loss, more preferably 1.5 or more, and still more preferably 2.0 or more. Note that, T2 is preferably 5 nm or more from the viewpoint of reducing the core loss while securing insulation. It could be confirmed that an upper limit of T2 is determined on the basis of T1, and may be, for example, 150 nm or less, 100 nm or less, or 50 nm or less.

(Experiment 3)

In Experiment 3, magnetic cores (Sample Nos. 49 to 56) shown in Table 2 were manufactured by changing the composition of the insulation coating provided in the first large particles and the second large particles. Manufacturing conditions other than the composition of the insulation coating were set to be similar as in manufacturing conditions as in Sample No. 32 in Experiment 2, and similar evaluation as in Experiment 1 was made on the respective samples in Experiment 3.

Cross-section observation results, and measurement results of the magnetic permeability, the DC bias characteristics ((μ0−μHdc)/μ0), and the core loss in Experiment 3 are shown in Table 2.

TABLE 2

Amorphous first large particles
Nanocrystalline second large particles

Example/

Coating

Coating

Comparative

thickness

thickness
Small

Sample No.
Example
Coating composition
T1 (nm)
Coating composition
T2 (nm)
particles

32
Example
P—Zn—Al—O-based
100
P—Zn—Al—O-based
15
Fe

49
Example
Bi—Zn—B—Si—O-based
100
P—Zn—Al—O-based
15
Fe

50
Example
Ba—Zn—B—Si—Al—O-based
100
P—Zn—Al—O-based
15
Fe

51
Example
P—Zn—Al—O-based
100
Bi—Zn—B—Si—O-based
15
Fe

52
Example
Bi—Zn—B—Si—O-based
100
Bi—Zn—B—Si—O-based
15
Fe

53
Example
Ba—Zn—B—Si—Al—O-based
100
Bi—Zn—B—Si—O-based
15
Fe

54
Example
P—Zn—Al—O-based
100
Ba—Zn—B—Si—Al—O-based
15
Fe

55
Example
Bi—Zn—B—Si—O-based
100
Ba—Zn—B—Si—Al—O-based
15
Fe

56
Example
Ba—Zn—B—Si—Al—O-based
100
Ba—Zn—B—Si—Al—O-based
15
Fe

Magnetic

Area ratio (%)
permeability
DC bias
Core loss

First large
Second large
Small
Measured
characteristics
Measured

particles
particles
particles
value
Measured value
value

Sample No.
AL₁/A0
AL₂/A0
AS/A0
(μ0)
(Variation rate)
(kW/m³)

32
40.3
39.1
20.6
34.6
14.7%
520

49
40.8
40.8
18.4
35.1
14.0%
520

50
40.9
40.9
18.2
34.7
14.1%
510

51
40.1
40.1
19.8
35.1
13.9%
530

52
40.3
40.3
19.4
34.8
14.4%
520

53
40.7
40.7
18.6
35.3
13.8%
510

54
39.8
39.8
20.4
34.9
14.1%
520

55
40.4
40.4
19.2
34.7
14.1%
530

56
41.1
41.1
17.8
34.6
14.5%
530

In the respective samples in Experiment 3, the DC bias characteristics and the core loss were similar as in Sample No. 32 in Experiment 2, and the core loss could be reduced while maintaining good DC bias characteristics. It could be confirmed that the composition of the insulation coating formed on each of the large particles may be changed as in Table 2.

(Experiment 4)

In Example 4, magnetic core samples (Sample Nos. 57 to 74) shown in Table 3 were manufactured by changing the ratio (AL₁/A0) of the first large particles having the amorphous structure, and the ratio (AL₂/A0) of the second large particles having the nanocrystal structure.

In Sample Nos. 57 to 62 as comparative examples, T1 was set to 15 nm, T2 was set to 100 nm, and manufacturing conditions other than the ratios of the large particles were set to be similar as in Sample No. 22 in Experiment 2. In Sample Nos. 63 to 68, T1 and T2 were set to 15 nm, and manufacturing conditions other than the ratios of the large particles were set to be similar as in Sample No. 20 in Experiment 2. In Sample Nos. 69 to 74, T1 was set to 100 nm, T2 was set to 15 nm, and manufacturing conditions other than the ratios of the large particles were set to be similar as in Sample No. 32 in Experiment 2.

In Experiment 4, similar evaluation as in Experiment 2 was made. Evaluation results are shown in Table 3.

TABLE 3

Amorphous
Nanocrystalline

first large
second large

particles
particles

Area ratio (%)

Coating
Coating

First large
Second large

Sample
Example/
thickness
thickness
Small
particles
particles

No.
Comparative Example
T1 (nm)
T2 (nm)
particles
AL₁/A0
AL₂/A0

2
Comparative Example
15
—
Fe
80.8
—

57
Comparative Example
15
100
Fe
76.0
3.7

58
Comparative Example
15
100
Fe
71.5
7.1

59
Comparative Example
15
100
Fe
64.2
16.4

22
Comparative Example
15
100
Fe
41.0
40.9

60
Comparative Example
15
100
Fe
15.5
64.3

61
Comparative Example
15
100
Fe
8.6
72.3

62
Comparative Example
15
100
Fe
3.6
76.7

10
Comparative Example
—
100
Fe
—
80.5

2
Comparative Example
15
—
Fe
80.8
—

63
Comparative Example
15
15
Fe
76.3
3.6

64
Comparative Example
15
15
Fe
72.0
7.9

65
Comparative Example
15
15
Fe
64.3
16.1

20
Comparative Example
15
15
Fe
40.4
40.7

66
Comparative Example
15
15
Fe
16.1
64.1

67
Comparative Example
15
15
Fe
8.3
72.7

68
Comparative Example
15
15
Fe
4.0
76.6

8
Comparative Example
—
15
Fe
—
79.8

4
Comparative Example
100
—
Fe
80.8
—

69
Example
100
15
Fe
75.7
4.5

70
Example
100
15
Fe
71.3
7.7

71
Example
100
15
Fe
64.5
16.3

32
Example
100
15
Fe
40.3
39.1

72
Example
100
15
Fe
15.3
64.2

73
Example
100
15
Fe
8.3
72.6

74
Example
100
15
Fe
5.1
76.6

8
Comparative Example
—
15
Fe
—
79.8

Magnetic
DC bias characteristics

Area ratio (%)
permeability
Measured

Core loss

Small
Measured
value

Measured

Sample
particles
value
(Variation
Improvement
value
Improvement

No.
AS/A0
(μ0)
rate)
rate
(kW/m³)
rate

2
19.2
35.3
8.3%
—
910
—

57
20.3
35.2
7.7%
1.1%
870
0.4%

58
21.4
34.9
8.1%
1.1%
840
−0.1%

59
19.4
35.2
9.7%
1.2%
820
−2.2%

22
18.1
34.5
14.0%
1.1%
690
4.6%

60
20.2
35.4
17.2%
1.5%
520
−7.0%

61
19.1
35.3
18.8%
1.3%
480
−7.4%

62
19.7
34.7
18.6%
2.1%
450
−9.2%

10
19.5
34.6
21.4%
—
390
—

2
19.2
35.3
8.3%
—
910
—

63
20.1
35.1
8.8%
0.0%
870
0.7%

64
20.1
34.9
9.5%
0.0%
850
−0.2%

65
19.6
34.6
10.8%
0.1%
800
0.1%

20
18.9
35.4
14.8%
0.1%
640
1.3%

66
19.8
34.8
18.4%
0.3%
480
1.4%

67
19.0
34.9
20.2%
−0.1%
450
−2.3%

68
19.4
35.4
20.5%
0.2%
420
−2.5%

8
20.2
34.5
21.2%
—
380
—

4
19.2
35.4
8.5%
—
940
—

69
19.8
34.7
9.1%
0.1%
800
11.4%

70
21.0
35.5
9.4%
0.1%
760
12.3%

71
19.2
35.3
11.0%
0.1%
700
15.5%

32
20.6
34.6
14.7%
−0.1%
520
20.6%

72
20.5
35.1
18.2%
0.4%
410
15.3%

73
19.1
35.0
20.1%
0.0%
390
11.8%

74
18.3
35.3
20.7%
0.2%
390
8.1%

8
20.2
34.5
21.2%
—
380
—

As shown in Table 3, in examples satisfying a relationship of T1>T2, even when changing the mixing ratio of the first large particles and the second large particles, the core loss could be reduced by 5% or more even in amorphous magnetic cores. Particularly, it could be confirmed that any of AL₁/A0 and AL₂/A0 is preferably 3% or more, more preferably 4% to 78%, and still more preferably 7% to 44%.

In addition, from results shown in Table 3, it could be confirmed that each of AL₁/(AL₁+AL₂) and AL₂/(AL₁+AL₂) may be set within a range of 4% to 96%, AL₁/(AL₁+AL₂) is more preferably 50% to 96% from the viewpoint of obtaining excellent DC bias characteristics, and AL₂/(AL₁+AL₂) is more preferably 50% to 90% from the viewpoint of further lowering the core loss.

Furthermore, it could also be confirmed that from the viewpoints of improving the core loss and the DC bias characteristics with balance and of enhancing the effect of improving the core loss, AL₁/(AL₁+AL₂) is preferably 10% to 94%, and more preferably 18% to 85%.

(Experiment 5)

In Experiment 5, magnetic core samples (Sample Nos. 75 to 92) shown in Table 4 were manufactured by changing the ratio (AS/A0) of the small particles. In the respective samples in Experiment 5, large particles having the amorphous structure and large particles having the nanocrystal structure were mixed in a ratio of approximately “1:1”. Manufacturing conditions other than the ratio of the small particles were set to be similar as in Experiment 2 except that the molding pressure was changed in conformity to a mixing ratio of the small particles, and the magnetic permeability, the DC bias characteristics ((μ0−μHdc)/μ0), and the core loss were measured. Evaluation results are shown in Table 4.

TABLE 4

Amorphous
Nanocrystalline

first large
second large

Magnetic

particles
particles

Area ratio (%)
permeability
DC bias
Core loss

Example/
Coating
Coating

First large
Second large
Small
Measured
characteristics
Measured

Sample
Comparative
thickness
thickness
Small
particles
particles
particles
value
Measured value
value

No.
Example
T1 (nm)
T2 (nm)
particles
AL₁/A0
AL₂/A0
AS/A0
(μ0)
(Variation rate)
(kW/m³)

75
Comparative
15
100
—
48.7
51.3
0
25.2
14.8%
890

Example

76
Comparative
15
15
—
49.9
50.1
0
25.4
17.3%
880

Example

77
Example
100
15
—
50.5
49.5
0
25.3
17.6%
630

78
Comparative
15
100
Fe
47.5
47.7
4.8
30.3
14.4%
850

Example

79
Comparative
15
15
Fe
47.3
47.8
4.9
30.1
16.1%
840

Example

80
Example
100
15
Fe
47.6
47.4
5.0
30.2
16.3%
610

81
Comparative
15
100
Fe
45.9
45.9
8.2
34.3
15.2%
830

Example

82
Comparative
15
15
Fe
45.4
45.4
9.2
34.2
16.3%
820

Example

83
Example
100
15
Fe
43.8
43.8
12.4
34.1
16.4%
600

22
Comparative
15
100
Fe
41.0
40.9
18.1
34.5
14.0%
690

Example

20
Comparative
15
15
Fe
40.4
40.7
18.9
35.4
14.8%
650

Example

32
Example
100
15
Fe
40.3
39.1
20.6
34.6
14.7%
520

84
Comparative
15
100
Fe
27.5
27.5
45.0
30.3
12.2%
540

Example

85
Comparative
15
15
Fe
28.1
28.1
43.8
30.4
13.1%
520

Example

86
Example
100
15
Fe
30.8
30.8
38.4
30.1
13.2%
410

87
Comparative
15
100
Fe
20.0
20.0
60.0
25.2
10.2%
480

Example

88
Comparative
15
15
Fe
19.8
19.8
60.4
25.3
11.1%
470

Example

89
Example
100
15
Fe
16.8
16.8
66.4
25.4
11.4%
350

90
Comparative
15
100
Fe
11.5
11.5
77.0
20.1
9.2%
450

Example

91
Comparative
15
15
Fe
10.1
10.1
79.8
20.3
10.2%
480

Example

92
Example
100
15
Fe
9.2
9.2
81.6
20.4
10.3%
320

As shown in Table 4, even in a case of changing the ratio of the small particles, in examples in which T1/T2 is more than 1.0, the core loss was further lowered by 20% or more in comparison to comparative examples in which T1/T2 is 1.0 or less.

Note that, when increasing the ratio of the small particles in the magnetic cores, it could be confirmed that the core loss and the DC bias characteristics tends to be further improved, and the magnetic permeability tends to be decreased. From the viewpoint of improving the core loss and the DC bias characteristics while securing high magnetic permeability, it could be confirmed that the ratio (AS/A0) of the small particles is preferably 5% to 85%, and more preferably 5% or more and less than 50%, 5% to 40%, and 10% to 40% in this order.

(Experiment 6)

In Experiment 6, magnetic core samples shown in Table 5 were manufactured by changing the packing rate (that is, A0) of the metal magnetic particles. The packing rate of the metal magnetic particles was controlled on the basis of an addition amount of an epoxy resin. The amount of the resin (the content of the epoxy resin with respect to the metal magnetic particles), and the total area ratio A0 of the metal magnetic particles in respective samples in Experiment 6 are shown in Table 5.

Experiment conditions other than the above-described conditions were set to be similar as in Experiment 2, and the magnetic permeability, the DC bias characteristics, and the core loss of the respective samples were evaluated. Results are shown in Table 5.

TABLE 5

Nanocrystalline

Amorphous first
second large

large particles
particles

Area ratio (%)

Example/
Coating
Coating

First large

Sample
Comparative
thickness
thickness
Small
A0
particles

No.
Example
T1 (nm)
T2 (nm)
particles
(%)
AL₁/A0

93
Comparative
15
100
Fe
89.6
39.1

Example

94
Comparative
15
15
Fe
89.4
40.8

Example

95
Example
100
15
Fe
89.9
39.8

96
Comparative
15
100
Fe
88.0
40.1

Example

97
Comparative
15
15
Fe
87.9
40.3

Example

98
Example
100
15
Fe
87.8
40.3

22
Comparative
15
100
Fe
79.3
41.0

Example

20
Comparative
15
15
Fe
79.6
40.4

Example

32
Example
100
15
Fe
79.0
40.3

99
Comparative
15
100
Fe
74.7
40.1

Example

100
Comparative
15
15
Fe
75.3
40.2

Example

101
Example
100
15
Fe
75.3
40.5

102
Comparative
15
100
Fe
71.1
40.8

Example

103
Comparative
15
15
Fe
70.8
38.9

Example

104
Comparative
100
15
Fe
70.1
41.0

Example

Magnetic

Area ratio (%)

permeability
DC bias
Core loss

Second large
Small
Amount of
Measured
characteristics
Measured

Sample
particles
particles
resin
value
Measured value
value

No.
AL₂/A0
AS/A0
wt %
(μ0)
(Variation rate)
(kW/m³)

93
41.0
19.9
1.0
44.0
29.0%
890

94
41.0
18.2
1.0
43.4
30.3%
900

95
40.0
20.2
1.0
44.6
30.2%
700

96
40.3
19.6
1.2
40.5
24.3%
880

97
40.5
19.2
1.2
40.6
24.9%
870

98
40.4
19.3
1.2
40.5
24.8%
670

22
40.9
18.1
2.5
34.5
14.0%
690

20
40.7
18.9
2.5
35.4
14.8%
650

32
39.1
20.6
2.5
34.6
14.7%
520

99
40.8
19.1
3.5
30.1
11.1%
640

100
39.5
20.3
3.5
30.3
12.2%
650

101
39.4
20.1
3.5
30.3
12.4%
510

102
40.7
18.5
4.0
24.4
10.4%
630

103
39.5
21.6
4.0
24.5
10.4%
620

104
39.4
19.6
4.0
24.6
10.5%
590

As shown in Table 5, Sample Nos. 95, 98, 32, and 101 are examples in Experiment 6, and in a case where A0 is 75% or more and T1/T2 is more than 1.0, it could be confirmed that the core loss is further lowered by 20% or more in comparison to comparative examples in which T1/T2 is 1.0 or less.

Note that, as shown in Table 5, it could be confirmed that when increasing the packing rate of the metal magnetic particles, the magnetic permeability μ0 tends to increase, and the core loss characteristics and the DC bias characteristics tend to deteriorate. It could be understood that A0 is preferably 90% or less from the viewpoint of maintaining a low core loss, and more preferably 80% or less.

(Experiment 7)

In Experiment 7, magnetic core samples shown in Table 6 and Table 7 were manufactured by changing specifications of the small particles. Specifically, in Sample No. 105, Fe—Ni-based alloy particles having an average particle size of 1 μm were used as the small particles, in Sample No. 106, Fe—Si-based alloy particles having an average particle size of 1 μm were used as the small particles, in Sample No. 107, Fe—Co-based alloy particles having an average particle size of 1 μm were used as the small particles, and in Sample No. 108, Co particles having an average particle size of 1 μm were used as the small particles. An insulation coating of Ba—Zn—B—Si—Al—O-based oxide glass having an average thickness of 15±10 nm was formed on the small particles of respective samples shown in Table 6. Manufacturing conditions other than the composition of the small particles were set to be similar as in Sample No. 32 in Experiment 2.

In addition, in Sample Nos. 109 and 110 shown in Table 7, two kinds of small particles different in a coating composition were added. Specifically, in Sample No. 109, Fe particles (first small particles) on which a coating of Ba—Zn—B—Si—Al—O-based oxide glass was formed, and Fe particles (second small particles) on which an Si—O-based insulation coating was formed were mixed.

In addition, in Sample No. 110, Fe particles (first small particles) on which a coating of Si—Ba—Mn—O-based oxide glass was formed and Fe particles (second small particles) on which a Si—O-based insulation coating was formed were mixed. In Sample Nos. 109 and 110, an average thickness of the insulation coating of the small particles was within a range of 15±10 nm. Manufacturing conditions other than the above-described conditions were set to be similar as in Sample No. 32 in Experiment 2.

Evaluation results in Experiment 7 are shown in Table 6 and Table 7.

TABLE 6

Nanocrystalline

Amorphous first
second large

Magnetic

large particles
particles

Area ratio (%)
permeability
DC bias
Core loss

Example/
Coating
Coating

First large
Second large
Small
Measured
characteristics
Measured

Sample
Comparative
thickness
thickness
Small
particles
particles
particles
value
Measured value
value

No.
Example
T1 (nm)
T2 (nm)
particles
AL₁/A0
AL₂/A0
AS/A0
(μ0)
(Variation rate)
(kW/m³)

32
Example
100
15
Fe
40.3
39.1
20.6
34.6
14.7%
520

105
Example
100
15
Fe—Ni
39.6
41.2
19.2
34.8
14.1%
500

106
Example
100
15
Fe—Si
40.0
39.8
20.2
34.2
14.3%
510

107
Example
100
15
Fe—Co
40.2
40.1
19.7
34.1
14.5%
500

108
Example
100
15
Co
39.8
40.2
20.0
35.1
14.7%
510

TABLE 7

Amorphous
Nanocrystalline

first large
second large

particles
particles

Example/
Coating
Coating

Second small

Sample
Comparative
thickness
thickness
First small particles
particles

No.
Example
T1 (nm)
T2 (nm)
Composition
Coating composition
Composition

32
Example
100
15
Fe
Ba—Zn—B—Si—Al—O-based
—

109
Example
100
15
Fe
Ba—Zn—B—Si—Al—O-based
Fe

110
Example
100
15
Fe
Si—Ba—Mn ⁻O-based
Fe

Area ratio (%)
Magnetic

Second small
First
Second
First
Second
permeability
DC bias
Core loss

particles
large
large
small
small
Measured
characteristics
Measured

Sample
Coating
particles
particles
particles
particles
value
Measured value
value

No.
composition
AL₁/A0
AL₂/A0
AS₁/A0
AS₂/A0
(μ0)
(Variation rate)
(kW/m³)

32
—
40.3
39.1
20.6
—
34.6
14.7%
520

109
Si—O-based
40.1
39.5
9.8
10.6
34.6
13.9%
510

110
Si—O-based
39.3
39.8
10.1
10.8
34.8
13.1%
520

As shown in Table 6, even in Sample Nos. 105 to 108 in which the composition of the small particles was changed, the core loss could be reduced while maintaining good DC bias characteristics as in Sample No. 32 in Experiment 2. From the results, it could be understood that in a case of adding the small particles to the magnetic core, the composition of the small particles is not particularly limited and can be arbitrarily set.

As shown in Table 7, in Sample Nos. 109 and 110, the DC bias characteristics could be further improved while maintaining a low core loss in comparison to Sample No. 32 in Experiment 2. From the result, it could be understood that when two kinds of small particles different in a coating composition are dispersed in the magnetic core, the DC bias characteristics can be improved while maintaining the low core loss.

(Experiment 8)

In Experiment 8, three kinds of magnetic core samples (Sample Nos. 111 to 113) shown in Table 8 were manufactured by adding medium particles in combination with the first large particles, the second large particles, and the small particles. Specifically, nanocrystalline Fe—Si—B—Nb—Cu-based alloy particles having an average particle size of 5 μm were added to the magnetic core of Sample No. 111 as the medium particles, crystalline Fe—Si-based alloy particles having an average particle size of 5 μm were added to the magnetic core of Sample No. 112 as the medium particles, and amorphous Fe—Si—B-based alloy particles having an average particle size of 5 μm were added to the magnetic core of Sample No. 113 as the medium particles. Note that, in any of the medium particles used in Experiment 8, D20 was less than 3 μm, and D80 was 3 μm or more. In addition, a coating may not be formed on the medium particles, but the coating is preferably formed from the viewpoint of insulation. In the medium particles used in this experiment, a similar coating powder using P—Zn—Al—O-based oxide glass having an average thickness of 15±10 nm as in the large particles was used.

Manufacturing conditions other than the above-described conditions were set to be similar as in Sample No. 32 in Experiment 2, and the magnetic permeability, the DC bias characteristics, and the core loss were measured. Evaluation results are shown in Table 8.

TABLE 8

Nanocrystalline

Amorphous first
second large

large particles
particles

Area ratio (%)

Example/
Coating
Coating
Structure of

First large

Sample
Comparative
thickness
thickness
medium
Small
particles

No.
Example
T1 (nm)
T2 (nm)
particles
particles
AL₁/A0

32
Example
100
15
—
Fe
40.3

111
Example
100
15
Nanocrystal
Fe
39.5

112
Example
100
15
Crystal
Fe
41.1

113
Example
100
15
Amorphous
Fe
38.9

Magnetic

Area ratio (%)
permeability
DC bias
Core loss

Second large
Medium
Small
Measured
characteristics
Measured

Sample
particles
particles
particles
value
Measured value
value

No.
AL₂/A0
AM/A0
AS/A0
(μ0)
(Variation rate)
(kW/m³)

32
39.1
0.0
20.6
34.6
14.7%
520

111
39.9
10.2
10.4
34.3
13.6%
540

112
39.3
10.2
9.4
34.6
13.5%
580

113
40.0
10.5
10.6
35.1
13.2%
560

As shown in Table 8, even in the respective examples in which the medium particles were added, the core loss could be reduced while maintaining good DC bias characteristics as in Sample No. 32 in Experiment 2. From the evaluation results in Experiment 8, it could be understood that the medium particles may be added to the magnetic core.

(Experiment 9)

In Experiment 9, magnetic core samples shown in Table 9A and Table 9B were manufactured by changing the composition of the first large particles having the amorphous structure and the composition of the second large particles having the nanocrystal structure. An average particle size of any of the first large particles used in Experiment 9 was 20 μm, and the degree of amorphization of the first large particles was 85% or more. In addition, an average particle size of any of the second large particles used in Experiment 9 was 20 μm, and an average crystallite diameter in the second large particles was within a range of 0.5 to 30 nm.

Note that, Sample Nos. 114 to 136 shown in Table 9A are comparative examples in which only either the first large particles having the amorphous structure or the second large particles having the nanocrystal structure was used. Manufacturing conditions other than a particle composition of Sample Nos. 114 to 136 were set to be similar as in Sample No. 4 or 8 in Experiment 1. Respective examples shown in Table 9B to Table 9G are examples in which the first large particles and the second large particles were mixed. Manufacturing conditions other than the particle composition of respective examples were set to be similar as in Sample No. 32 in Experiment 2.

Evaluation results in Experiment 9 are shown in Table 9A to Table 9G.

TABLE 9A

Example/
Large particles

Comparative

Coating

Sample No.
Example
Structure
Particle composition
composition

4
Comparative
Amorphous
Fe—Co—B—P—Si—Cr-based
P—Zn—Al—O-

Example

based

114
Comparative
Amorphous
Fe—Si—B-based
P—Zn—Al—O-

Example

based

115
Comparative
Amorphous
Fe—Si—B—C-based
P—Zn—Al—O-

Example

based

116
Comparative
Amorphous
Fe—Si—B—C⁻Cr-based
P—Zn—Al—O-

Example

based

117
Comparative
Amorphous
Fe—P—B-based
P—Zn—Al—O-

Example

based

118
Comparative
Amorphous
Fe—P—B—C-based
P—Zn—Al—O-

Example

based

119
Comparative
Amorphous
Fe—Co—P—C-based
P—Zn—Al—O-

Example

based

120
Comparative
Amorphous
Fe—Co—B-based
P—Zn—Al—O-

Example

based

121
Comparative
Amorphous
Fe—Co—B—Si-based
P—Zn—Al—O-

Example

based

122
Comparative
Amorphous
Fe—Co—Si—B—C-based
P—Zn—Al—O-

Example

based

123
Comparative
Amorphous
Fe—Co—Si—B—C⁻Cr-based
P—Zn—Al—O-

Example

based

124
Comparative
Amorphous
Fe—Co—P—B-based
P—Zn—Al—O-

Example

based

125
Comparative
Amorphous
Fe—Co—P—B—C-based
P—Zn—Al—O-

Example

based

8
Comparative
Nanocrystal
Fe—Si—B—Nb—Cu-based
P—Zn—Al—O-

Example

based

126
Comparative
Nanocrystal
Fe—Si—B—Nb—P-based
P—Zn—Al—O-

Example

based

127
Comparative
Nanocrystal
Fe—P—B—Cu-based
P—Zn—Al—O-

Example

based

128
Comparative
Nanocrystal
Fe—B—Nb—P-based
P—Zn—Al—O-

Example

based

129
Comparative
Nanocrystal
Fe—B—Nb—P—Si-based
P—Zn—Al—O-

Example

based

130
Comparative
Nanocrystal
Fe—B—Nb—P—Si—Cr-based
P—Zn—Al—O-

Example

based

131
Comparative
Nanocrystal
Fe—Co—Si—B—Nb—Cu-based
P—Zn—Al—O-

Example

based

132
Comparative
Nanocrystal
Fe—Co—Si—B—Nb—P-based
P—Zn—Al—O-

Example

based

133
Comparative
Nanocrystal
Fe—Co—P—B—Cu-based
P—Zn—Al—O-

Example

based

134
Comparative
Nanocrystal
Fe—Co—B—Nb—P-based
P—Zn—Al—O-

Example

based

135
Comparative
Nanocrystal
Fe—Co—B—Nb—P—Si-based
P—Zn—Al—O-

Example

based

136
Comparative
Nanocrystal
Fe—Co—B—Nb—P—Si—Cr-based
P—Zn—Al—O-

Example

based

Large

Magnetic

particles

permeability
DC bias
Core loss

Coating

Measured
characteristics
Measured

thickness
Small
Area ratio (%)
value
Measured value
value

Sample No.
(nm)
particles
AL/A0
AS/A0
(μ0)
(Variation rate)
(kW/m³)

4
100
Fe
80.8
19.2
35.4
8.5%
940

114
100
Fe
78.8
21.2
34.8
8.5%
880

115
100
Fe
80.7
19.3
35.4
8.6%
890

116
100
Fe
81.1
18.9
35.0
8.6%
900

117
100
Fe
80.2
19.8
35.1
8.6%
920

118
100
Fe
80.1
19.9
35.2
8.3%
910

119
100
Fe
80.3
19.7
35.3
8.2%
900

120
100
Fe
79.9
20.1
35.3
7.3%
1020

121
100
Fe
82.0
18.0
34.6
7.0%
980

122
100
Fe
80.5
19.5
35.1
7.0%
1200

123
100
Fe
80.4
19.6
35.1
7.2%
1100

124
100
Fe
80.1
19.9
35.2
7.3%
1150

125
100
Fe
80.4
19.6
34.8
7.5%
1100

8
15
Fe
79.8
20.2
34.5
21.2%
380

126
15
Fe
79.5
20.5
34.4
20.1%
500

127
15
Fe
79.6
20.4
34.6
20.1%
520

128
15
Fe
80.1
19.9
35.5
19.8%
540

129
15
Fe
80.2
19.8
35.2
19.4%
550

130
15
Fe
79.3
20.7
35.4
19.5%
530

131
15
Fe
79.6
20.4
35.4
18.3%
540

132
15
Fe
80.2
19.8
35.2
18.3%
550

133
15
Fe
80.3
19.7
35.1
18.5%
570

134
15
Fe
80.5
19.5
35.1
18.6%
540

135
15
Fe
79.8
20.2
34.6
20.8%
450

136
15
Fe
80.0
20.0
34.9
21.1%
500

TABLE 9B

Area ratio (%)

Example/
Amorphous first large
Nanocrystalline second large
First large
Second large

Comparative
particles
particles
particles
particles

Sample No.
Example
Particle composition
Particle composition
AL₁/A0
AL₂/A0

32
Example
Fe—Co—B—P—Si—Cr-based
Fe—Si—B—Nb—Cu-based
40.3
39.1

137
Example
Fe—Si—B-based
Fe—Si—B—Nb—Cu-based
40.4
41.1

138
Example
Fe—Si—B—C-based
Fe—Si—B—Nb—Cu-based
40.8
39.7

139
Example
Fe—Si—B—C⁻Cr-based
Fe—Si—B—Nb—Cu-based
39.3
40.4

140
Example
Fe—P—B-based
Fe—Si—B—Nb—Cu-based
40.0
40.1

141
Example
Fe—P—B—C-based
Fe—Si—B—Nb—Cu-based
41.2
39.4

142
Example
Fe—Co—P—C-based
Fe—Si—B—Nb—Cu-based
41.4
40.6

143
Example
Fe—Co—B-based
Fe—Si—B—Nb—Cu-based
40.5
41.0

144
Example
Fe—Co—B—Si-based
Fe—Si—B—Nb—Cu-based
39.8
39.8

145
Example
Fe—Co—Si—B—C-based
Fe—Si—B—Nb—Cu-based
40.7
38.7

146
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—Si—B—Nb—Cu-based
41.4
40.7

147
Example
Fe—Co—P—B-based
Fe—Si—B—Nb—Cu-based
39.8
39.6

148
Example
Fe—Co—P—B—C-based
Fe—Si—B—Nb—Cu-based
39.4
41.1

149
Example
Fe—Co—B—P—Si—Cr-based
Fe—Si—B—Nb—P-based
40.3
38.6

150
Example
Fe—Si—B-based
Fe—Si—B—Nb—P-based
40.4
38.8

151
Example
Fe—Si—B—C-based
Fe—Si—B—Nb—P-based
40.7
39.9

152
Example
Fe—Si—B—C⁻Cr-based
Fe—Si—B—Nb—P-based
40.3
40.4

153
Example
Fe—P—B-based
Fe—Si—B—Nb—P-based
39.3
41.3

154
Example
Fe—P—B—C-based
Fe—Si—B—Nb—P-based
40.2
39.4

155
Example
Fe—Co—P—C-based
Fe—Si—B—Nb—P-based
38.7
39.8

156
Example
Fe—Co—B-based
Fe—Si—B—Nb—P-based
41.2
39.5

157
Example
Fe—Co—B—Si-based
Fe—Si—B—Nb—P-based
39.6
40.7

158
Example
Fe—Co—Si—B—C-based
Fe—Si—B—Nb—P-based
40.6
40.0

159
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—Si—B—Nb—P-based
39.0
41.5

160
Example
Fe—Co—P—B-based
Fe—Si—B—Nb—P-based
40.5
39.1

161
Example
Fe—Co—P—B—C-based
Fe—Si—B—Nb—P-based
39.6
39.9

DC bias

Magnetic
characteristics

Area ratio (%)
permeability
Measured

Core loss

Small
Measured
value

Measured

particles
value
(Variation
Improvement
value
Improvement

Sample No.
AS/A0
(μ0)
rate)
rate
(kW/m³)
rate

32
20.6
34.6
14.7%
−0.1%
520
20.6%

137
18.5
35.1
14.9%
0.4%
530
18.1%

138
19.5
35.3
14.8%
0.1%
530
17.1%

139
20.3
34.7
14.6%
0.3%
520
17.3%

140
19.9
35.0
14.4%
0.5%
530
18.4%

141
19.4
34.7
14.5%
0.2%
530
19.2%

142
18.0
34.6
14.8%
0.2%
530
19.4%

143
18.5
34.7
14.5%
0.1%
550
22.8%

144
20.4
34.5
14.2%
−0.2%
530
20.3%

145
20.6
35.3
14.0%
−0.2%
600
24.1%

146
17.9
35.5
14.3%
0.2%
610
19.8%

147
20.6
35.0
14.0%
0.1%
600
21.1%

148
19.5
35.1
14.5%
0.1%
600
18.3%

149
21.1
34.6
14.0%
0.0%
580
18.5%

150
20.8
35.3
14.3%
−0.1%
540
22.3%

151
19.4
34.8
14.0%
0.4%
560
20.0%

152
19.3
34.8
14.1%
0.4%
570
18.7%

153
19.4
35.0
15.1%
−0.4%
550
22.6%

154
20.4
35.1
13.8%
0.3%
560
20.5%

155
21.5
35.2
14.1%
−0.1%
560
18.1%

156
19.3
35.5
13.6%
0.2%
630
18.6%

157
19.7
35.2
13.7%
0.0%
570
21.8%

158
19.4
34.6
14.0%
−0.4%
680
20.6%

159
19.5
35.2
14.3%
−0.3%
650
18.2%

160
20.4
34.7
13.6%
0.0%
640
22.6%

161
20.5
35.2
13.6%
0.2%
650
18.0%

TABLE 9C

Area ratio (%)

Example/
Amorphous first large
Nanocrystalline second large
First large
Second large

Comparative
particles
particles
particles
particles

Sample No.
Example
Particle composition
Particle composition
AL₁/A0
AL₂/A0

162
Example
Fe—Co—B—P—Si—Cr-based
Fe—P—B—Cu-based
41.2
41.3

163
Example
Fe—Si—B-based
Fe—P—B—Cu-based
40.5
39.4

164
Example
Fe—Si—B—C-based
Fe—P—B—Cu-based
38.7
41.4

165
Example
Fe—Si—B—C⁻Cr-based
Fe—P—B—Cu-based
40.6
39.7

166
Example
Fe—P—B-based
Fe—P—B—Cu-based
40.3
39.7

167
Example
Fe—P—B—C-based
Fe—P—B—Cu-based
41.0
39.8

168
Example
Fe—Co—P—C-based
Fe—P—B—Cu-based
39.3
40.0

169
Example
Fe—Co—B-based
Fe—P—B—Cu-based
40.9
40.0

170
Example
Fe—Co—B—Si-based
Fe—P—B—Cu-based
39.7
39.4

171
Example
Fe—Co—Si—B—C-based
Fe—P—B—Cu-based
38.6
39.5

172
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—P—B—Cu-based
39.0
40.0

173
Example
Fe—Co—P—B-based
Fe—P—B—Cu-based
38.6
39.6

174
Example
Fe—Co—P—B—C-based
Fe—P—B—Cu-based
39.2
40.6

175
Example
Fe—Co—B—P—Si—Cr-based
Fe—B—Nb—P-based
38.9
41.4

176
Example
Fe—Si—B-based
Fe—B—Nb—P-based
41.0
41.5

177
Example
Fe—Si—B—C-based
Fe—B—Nb—P-based
40.1
40.4

178
Example
Fe—Si—B—C⁻Cr-based
Fe—B—Nb—P-based
41.4
39.0

179
Example
Fe—P—B-based
Fe—B—Nb—P-based
41.2
40.4

180
Example
Fe—P—B—C-based
Fe—B—Nb—P-based
39.3
39.8

181
Example
Fe—Co—P—C-based
Fe—B—Nb—P-based
41.0
39.4

182
Example
Fe—Co—B-based
Fe—B—Nb—P-based
41.2
39.2

183
Example
Fe—Co—B—Si-based
Fe—B—Nb—P-based
38.8
38.6

184
Example
Fe—Co—Si—B—C-based
Fe—B—Nb—P-based
38.9
40.3

185
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—B—Nb—P-based
40.0
41.1

186
Example
Fe—Co—P—B-based
Fe—B—Nb—P-based
40.9
39.5

187
Example
Fe—Co—P—B—C-based
Fe—B—Nb—P-based
39.7
40.3

DC bias

Magnetic
characteristics

Area ratio (%)
permeability
Measured

Core loss

Small
Measured
value

Measured

particles
value
(Variation
Improvement
value
Improvement

Sample No.
AS/A0
(μ0)
rate)
rate
(kW/m³)
rate

162
17.5
34.9
13.9%
0.9%
600
19.9%

163
20.1
35.2
14.4%
−0.1%
570
19.7%

164
19.9
34.7
14.4%
0.2%
550
21.1%

165
19.7
35.1
14.3%
0.0%
570
19.7%

166
20.0
34.9
14.5%
−0.2%
570
21.0%

167
19.2
35.0
13.7%
0.6%
570
21.5%

168
20.7
35.5
13.7%
0.4%
550
21.6%

169
19.1
35.2
13.8%
0.0%
630
19.6%

170
20.9
34.7
13.7%
−0.4%
600
18.0%

171
21.9
34.8
13.3%
0.0%
690
17.2%

172
21.0
35.0
13.9%
−0.3%
650
18.2%

173
21.8
34.9
13.4%
0.1%
650
20.0%

174
20.2
34.6
13.9%
0.0%
620
22.6%

175
19.7
35.2
14.5%
−0.2%
600
18.0%

176
17.5
35.2
14.4%
0.3%
580
21.4%

177
19.5
35.4
13.8%
0.5%
580
18.8%

178
19.6
34.8
14.1%
−0.1%
580
19.7%

179
18.4
34.7
14.4%
0.0%
600
19.5%

180
20.9
35.1
13.9%
0.0%
560
21.7%

181
19.6
34.8
13.9%
0.0%
590
18.6%

182
19.6
34.7
13.3%
0.2%
630
20.3%

183
22.6
35.0
12.7%
0.2%
580
19.9%

184
20.8
35.1
13.0%
0.3%
680
20.1%

185
18.9
35.3
14.2%
−0.5%
660
19.9%

186
19.6
35.2
13.5%
0.0%
690
19.2%

187
20.0
34.8
13.7%
0.0%
640
21.5%

TABLE 9D

Area ratio (%)

Example/
Amorphous first large
Nanocrystalline second large
First large
Second large

Comparative
particles
particles
particles
particles

Sample No.
Example
Particle composition
Particle composition
AL₁/A0
AL₂/A0

188
Example
Fe—Co—B—P—Si—Cr-based
Fe—B—Nb—P—Si-based
40.8
40.0

189
Example
Fe—Si—B-based
Fe—B—Nb—P—Si-based
38.6
40.4

190
Example
Fe—Si—B—C-based
Fe—B—Nb—P—Si-based
40.2
39.6

191
Example
Fe—Si—B—C⁻Cr-based
Fe—B—Nb—P—Si-based
39.3
40.8

192
Example
Fe—P—B-based
Fe—B—Nb—P—Si-based
40.8
39.6

193
Example
Fe—P—B—C-based
Fe—B—Nb—P—Si-based
40.9
39.6

194
Example
Fe—Co—P—C-based
Fe—B—Nb—P—Si-based
38.8
40.2

195
Example
Fe—Co—B-based
Fe—B—Nb—P—Si-based
40.0
41.0

196
Example
Fe—Co—B—Si-based
Fe—B—Nb—P—Si-based
39.1
39.7

197
Example
Fe—Co—Si—B—C-based
Fe—B—Nb—P—Si-based
40.9
38.7

198
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—B—Nb—P—Si-based
40.2
38.6

199
Example
Fe—Co—P—B-based
Fe—B—Nb—P—Si-based
40.8
39.7

200
Example
Fe—Co—P—B—C-based
Fe—B—Nb—P—Si-based
41.3
40.3

201
Example
Fe—Co—B—P—Si—Cr-based
Fe—B—Nb—P—Si—Cr-based
40.7
39.0

202
Example
Fe—Si—B-based
Fe—B—Nb—P—Si—Cr-based
40.6
39.5

203
Example
Fe—Si—B—C-based
Fe—B—Nb—P—Si—Cr-based
39.4
39.1

204
Example
Fe—Si—B—C⁻Cr-based
Fe—B—Nb—P—Si—Cr-based
39.8
38.7

205
Example
Fe—P—B-based
Fe—B—Nb—P—Si—Cr-based
38.7
39.4

206
Example
Fe—P—B—C-based
Fe—B—Nb—P—Si—Cr-based
39.0
40.9

207
Example
Fe—Co—P—C-based
Fe—B—Nb—P—Si—Cr-based
39.2
38.7

208
Example
Fe—Co—B-based
Fe—B—Nb—P—Si—Cr-based
38.9
38.8

209
Example
Fe—Co—B—Si-based
Fe—B—Nb—P—Si—Cr-based
40.0
41.4

210
Example
Fe—Co—Si—B—C-based
Fe—B—Nb—P—Si—Cr-based
40.7
40.7

211
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—B—Nb—P—Si—Cr-based
38.9
40.7

212
Example
Fe—Co—P—B-based
Fe—B—Nb—P—Si—Cr-based
41.4
41.2

213
Example
Fe—Co—P—B—C-based
Fe—B—Nb—P—Si—Cr-based
38.6
41.4

Magnetic
DC bias characteristics

Area ratio (%)
permeability
Measured

Core loss

Small
Measured
value

Measured

particles
value
(Variation
Improvement
value
Improvement

Sample No.
AS/A0
(μ0)
rate)
rate
(kW/m³)
rate

188
19.2
35.3
13.5%
0.5%
590
21.3%

189
21.0
34.9
14.0%
−0.1%
580
18.1%

190
20.2
34.8
14.3%
−0.4%
570
20.3%

191
19.9
35.3
14.4%
−0.4%
580
19.0%

192
19.6
35.4
14.0%
0.0%
600
18.9%

193
19.5
35.0
14.1%
−0.3%
600
18.5%

194
21.0
35.3
13.9%
−0.2%
550
22.6%

195
19.0
35.3
13.7%
−0.1%
620
21.7%

196
21.2
34.7
12.6%
0.3%
600
18.9%

197
20.4
35.5
13.1%
−0.2%
710
18.9%

198
21.2
35.4
12.9%
0.0%
660
19.0%

199
19.5
35.4
13.7%
−0.4%
670
21.9%

200
18.4
35.4
13.2%
0.4%
660
21.6%

201
20.3
34.5
14.4%
−0.5%
570
22.4%

202
19.9
35.4
13.8%
0.3%
570
20.5%

203
21.5
34.8
13.3%
0.5%
540
22.4%

204
21.5
35.4
14.0%
−0.3%
580
17.2%

205
21.9
34.6
13.8%
0.0%
550
22.2%

206
20.1
35.0
14.4%
−0.3%
570
20.4%

207
22.1
35.4
13.7%
−0.2%
550
21.2%

208
22.3
34.7
12.7%
0.4%
620
18.0%

209
18.6
34.7
13.2%
0.4%
610
19.2%

210
18.6
34.5
13.4%
0.1%
720
18.1%

211
20.4
34.8
13.9%
−0.4%
640
20.4%

212
17.4
34.7
14.3%
−0.4%
700
19.5%

213
20.0
35.3
13.9%
−0.1%
640
20.5%

TABLE 9E

Area ratio (%)

Example/
Amorphous first large
Nanocrystalline second large
First large
Second large

Comparative
particles
particles
particles
particles

Sample No.
Example
Particle composition
Particle composition
AL₁/A0
AL₂/A0

214
Example
Fe—Co—B—P—Si—Cr-based
Fe—Co—Si—B—Nb—Cu-based
40.3
40.6

215
Example
Fe—Si—B-based
Fe—Co—Si—B—Nb—Cu-based
39.1
39.0

216
Example
Fe—Si—B—C-based
Fe—Co—Si—B—Nb—Cu-based
39.5
40.2

217
Example
Fe—Si—B—C⁻Cr-based
Fe—Co—Si—B—Nb—Cu-based
39.1
39.3

218
Example
Fe—P—B-based
Fe—Co—Si—B—Nb—Cu-based
39.5
39.3

219
Example
Fe—P—B—C-based
Fe—Co—Si—B—Nb—Cu-based
41.5
41.3

220
Example
Fe—Co—P—C-based
Fe—Co—Si—B—Nb—Cu-based
39.3
39.6

221
Example
Fe—Co—B-based
Fe—Co—Si—B—Nb—Cu-based
39.3
40.9

222
Example
Fe—Co—B—Si-based
Fe—Co—Si—B—Nb—Cu-based
39.2
41.1

223
Example
Fe—Co—Si—B—C-based
Fe—Co—Si—B—Nb—Cu-based
40.8
41.2

224
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—Co—Si—B—Nb—Cu-based
40.0
41.2

225
Example
Fe—Co—P—B-based
Fe—Co—Si—B—Nb—Cu-based
40.6
40.7

226
Example
Fe—Co—P—B—C-based
Fe—Co—Si—B—Nb—Cu-based
40.0
38.5

227
Example
Fe—Co—B—P—Si—Cr-based
Fe—Co—Si—B—Nb—P-based
39.7
40.4

228
Example
Fe—Si—B-based
Fe—Co—Si—B—Nb—P-based
39.8
41.2

229
Example
Fe—Si—B—C-based
Fe—Co—Si—B—Nb—P-based
38.6
41.2

230
Example
Fe—Si—B—C⁻Cr-based
Fe—Co—Si—B—Nb—P-based
40.5
40.0

231
Example
Fe—P—B-based
Fe—Co—Si—B—Nb—P-based
41.1
39.9

232
Example
Fe—P—B—C-based
Fe—Co—Si—B—Nb—P-based
40.4
39.4

233
Example
Fe—Co—P—C-based
Fe—Co—Si—B—Nb—P-based
40.7
41.1

234
Example
Fe—Co—B-based
Fe—Co—Si—B—Nb—P-based
40.5
40.9

235
Example
Fe—Co—B—Si-based
Fe—Co—Si—B—Nb—P-based
40.5
39.7

236
Example
Fe—Co—Si—B—C-based
Fe—Co—Si—B—Nb—P-based
39.0
38.9

237
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—Co—Si—B—Nb—P-based
39.0
40.6

238
Example
Fe—Co—P—B-based
Fe—Co—Si—B—Nb—P-based
39.2
39.5

239
Example
Fe—Co—P—B—C-based
Fe—Co—Si—B—Nb—P-based
41.5
40.7

Magnetic
DC bias characteristics

Area ratio (%)
permeability
Measured

Core loss

Small
Measured
value

Measured

particles
value
(Variation
Improvement
value
Improvement

Sample No.
AS/A0
(μ0)
rate)
rate
(kW/m³)
rate

214
19.1
35.0
13.9%
−0.3%
600
19.4%

215
21.9
34.9
13.0%
0.2%
560
20.1%

216
20.3
35.4
13.4%
0.1%
560
20.9%

217
21.6
35.1
13.4%
−0.2%
570
18.6%

218
21.2
34.9
13.4%
−0.1%
560
22.2%

219
17.2
35.2
13.4%
0.4%
600
20.2%

220
21.1
35.1
12.8%
0.3%
570
19.6%

221
19.8
35.2
13.2%
−0.2%
640
17.9%

222
19.7
34.7
13.3%
−0.5%
580
22.4%

223
18.0
34.7
13.1%
−0.1%
700
21.1%

224
18.8
34.9
13.4%
−0.3%
670
19.0%

225
18.7
34.9
12.9%
0.2%
690
19.7%

226
21.5
34.6
12.6%
0.0%
640
20.8%

227
19.9
34.5
13.8%
−0.4%
580
21.5%

228
19.0
34.9
13.9%
−0.2%
590
18.8%

229
20.2
34.7
13.8%
−0.3%
570
19.5%

230
19.5
34.7
13.6%
−0.2%
580
19.9%

231
19.0
35.2
13.3%
0.2%
580
22.2%

232
20.2
35.4
13.5%
−0.3%
590
19.1%

233
18.2
34.5
13.3%
0.2%
580
21.4%

234
18.6
34.6
13.0%
0.0%
640
19.7%

235
19.8
34.9
12.1%
0.4%
610
19.3%

236
22.1
35.4
12.3%
0.0%
660
22.2%

237
20.4
35.0
12.2%
0.6%
630
22.4%

238
21.3
34.7
13.5%
−0.9%
680
18.4%

239
17.8
34.8
12.5%
0.7%
680
19.7%

TABLE 9F

Area ratio (%)

Example/
Amorphous first large
Nanocrystalline second large
First large
Second large

Comparative
particles
particles
particles
particles

Sample No.
Example
Particle composition
Particle composition
AL₁/A0
AL₂/A0

240
Example
Fe—Co—B—P—Si—Cr-based
Fe—Co—P—B—Cu-based
41.1
39.5

241
Example
Fe—Si—B-based
Fe—Co—P—B—Cu-based
39.6
39.9

242
Example
Fe—Si—B—C-based
Fe—Co—P—B—Cu-based
40.0
40.9

243
Example
Fe—Si—B—C⁻Cr-based
Fe—Co—P—B—Cu-based
39.4
40.9

244
Example
Fe—P—B-based
Fe—Co—P—B—Cu-based
40.3
39.8

245
Example
Fe—P—B—C-based
Fe—Co—P—B—Cu-based
40.7
39.3

246
Example
Fe—Co—P—C-based
Fe—Co—P—B—Cu-based
39.9
41.0

247
Example
Fe—Co—B-based
Fe—Co—P—B—Cu-based
40.7
39.8

248
Example
Fe—Co—B—Si-based
Fe—Co—P—B—Cu-based
39.5
40.7

249
Example
Fe—Co—Si—B—C-based
Fe—Co—P—B—Cu-based
39.9
39.7

250
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—Co—P—B—Cu-based
40.0
40.4

251
Example
Fe—Co—P—B-based
Fe—Co—P—B—Cu-based
40.7
40.6

252
Example
Fe—Co—P—B—C-based
Fe—Co—P—B—Cu-based
41.3
39.6

253
Example
Fe—Co—B—P—Si—Cr-based
Fe—Co—B—Nb—P-based
38.6
39.7

254
Example
Fe—Si—B-based
Fe—Co—B—Nb—P-based
39.2
39.3

255
Example
Fe—Si—B—C-based
Fe—Co—B—Nb—P-based
39.2
41.4

256
Example
Fe—Si—B—C⁻Cr-based
Fe—Co—B—Nb—P-based
40.9
40.1

257
Example
Fe—P—B-based
Fe—Co—B—Nb—P-based
39.7
39.3

258
Example
Fe—P—B—C-based
Fe—Co—B—Nb—P-based
39.0
39.6

259
Example
Fe—Co—P—C-based
Fe—Co—B—Nb—P-based
40.2
39.4

260
Example
Fe—Co—B-based
Fe—Co—B—Nb—P-based
41.3
39.9

261
Example
Fe—Co—B—Si-based
Fe—Co—B—Nb—P-based
39.6
40.5

262
Example
Fe—Co—Si—B—C-based
Fe—Co—B—Nb—P-based
40.1
40.1

263
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—Co—B—Nb—P-based
40.7
41.3

264
Example
Fe—Co—P—B-based
Fe—Co—B—Nb—P-based
39.9
38.7

265
Example
Fe—Co—P—B—C-based
Fe—Co—B—Nb—P-based
39.1
40.0

Area ratio (%)
Magnetic
DC bias characteristics
Core loss

Small
permeability
Measured

Measured

particles
Measured
value
Improvement
value
Improvement

Sample No.
AS/A0
value (μ0)
(Variation rate)
rate
(kW/m³)
rate

240
19.4
35.4
13.3%
0.1%
600
20.9%

241
20.5
34.6
13.5%
0.0%
580
20.1%

242
19.1
34.5
14.2%
−0.5%
580
20.7%

243
19.7
35.1
13.9%
−0.3%
570
21.7%

244
19.9
35.4
13.2%
0.3%
610
18.1%

245
20.0
34.6
12.9%
0.4%
590
20.4%

246
19.1
35.3
13.8%
−0.3%
580
21.4%

247
19.5
35.3
12.8%
0.1%
650
19.0%

248
19.8
35.5
12.3%
0.4%
600
21.2%

249
20.4
34.8
13.0%
−0.4%
710
19.0%

250
19.6
35.3
13.4%
−0.5%
660
20.9%

251
18.7
35.4
13.0%
0.1%
700
19.8%

252
19.1
34.8
12.7%
0.3%
670
20.8%

253
21.7
35.2
13.1%
0.1%
580
19.0%

254
21.5
34.7
13.3%
0.0%
570
18.7%

255
19.4
35.3
13.5%
0.2%
570
19.7%

256
19.0
34.5
13.4%
0.2%
560
22.5%

257
21.0
34.7
13.4%
−0.1%
590
17.9%

258
21.4
35.1
13.3%
−0.1%
550
22.4%

259
20.4
35.0
13.5%
−0.3%
560
21.7%

260
18.8
34.6
13.0%
0.0%
640
19.5%

261
19.9
35.2
12.6%
0.1%
590
20.8%

262
19.8
34.8
12.3%
0.5%
710
18.1%

263
18.0
34.5
13.2%
0.0%
650
22.1%

264
21.4
34.8
12.9%
−0.3%
650
21.9%

265
20.9
34.8
12.5%
0.4%
630
21.6%

TABLE 9G

Area ratio (%)

Example/
Amorphous first large
Nanocrystalline second large
First large
Second large

Comparative
particles
particles
particles
particles

Sample No.
Example
Particle composition
Particle composition
AL₁/A0
AL₂/A0

266
Example
Fe—Co—B—P—Si—Cr-based
Fe—Co—B—Nb—P—Si-based
39.5
39.9

267
Example
Fe—Si—B-based
Fe—Co—B—Nb—P—Si-based
38.7
40.4

268
Example
Fe—Si—B—C-based
Fe—Co—B—Nb—P—Si-based
40.9
41.2

269
Example
Fe—Si—B—C⁻Cr-based
Fe—Co—B—Nb—P—Si-based
38.8
39.6

270
Example
Fe—P—B-based
Fe—Co—B—Nb—P—Si-based
39.4
40.2

271
Example
Fe—P—B—C-based
Fe—Co—B—Nb—P—Si-based
40.2
40.9

272
Example
Fe—Co—P—C-based
Fe—Co—B—Nb—P—Si-based
41.2
40.3

273
Example
Fe—Co—B-based
Fe—Co—B—Nb—P—Si-based
41.3
40.8

274
Example
Fe—Co—B—Si-based
Fe—Co—B—Nb—P—Si-based
40.8
39.6

275
Example
Fe—Co—Si—B—C-based
Fe—Co—B—Nb—P—Si-based
40.6
39.5

276
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—Co—B—Nb—P—Si-based
39.9
41.4

277
Example
Fe—Co—P—B-based
Fe—Co—B—Nb—P—Si-based
39.7
40.2

278
Example
Fe—Co—P—B—C-based
Fe—Co—B—Nb—P—Si-based
39.0
41.0

279
Example
Fe—Co—B—P—Si—Cr-based
Fe—Co—B—Nb—P—Si—Cr-based
41.2
40.1

280
Example
Fe—Si—B-based
Fe—Co—B—Nb—P—Si—Cr-based
39.6
40.7

281
Example
Fe—Si—B—C-based
Fe—Co—B—Nb—P—Si—Cr-based
40.8
39.8

282
Example
Fe—Si—B—C⁻Cr-based
Fe—Co—B—Nb—P—Si—Cr-based
41.1
41.2

283
Example
Fe—P—B-based
Fe—Co—B—Nb—P—Si—Cr-based
41.3
39.2

284
Example
Fe—P—B—C-based
Fe—Co—B—Nb—P—Si—Cr-based
41.3
41.0

285
Example
Fe—Co—P—C-based
Fe—Co—B—Nb—P—Si—Cr-based
41.5
41.4

286
Example
Fe—Co—B-based
Fe—Co—B—Nb—P—Si—Cr-based
38.9
40.8

287
Example
Fe—Co—B—Si-based
Fe—Co—B—Nb—P—Si—Cr-based
38.8
39.7

288
Example
Fe—Co—Si—B—C-based
Fe—Co—B—Nb—P—Si—Cr-based
40.5
39.1

289
Example
Fe—Co—Si—B—C⁻Cr-based
Fe—Co—B—Nb—P—Si—Cr-based
40.5
40.4

290
Example
Fe—Co—P—B-based
Fe—Co—B—Nb—P—Si—Cr-based
39.9
41.2

291
Example
Fe—Co—P—B—C-based
Fe—Co—B—Nb—P—Si—Cr-based
40.9
39.8

Area ratio (%)
Magnetic
DC bias characteristics
Core loss

Small
permeability
Measured

Measured

particles
Measured
value
Improvement
value
Improvement

Sample No.
AS/A0
value (μ0)
(Variation rate)
rate
(kW/m³)
rate

266
20.6
35.3
14.5%
0.1%
540
21.1%

267
20.9
35.1
14.4%
0.3%
530
19.7%

268
17.9
35.3
14.9%
0.2%
560
18.1%

269
21.6
34.5
14.3%
0.1%
530
18.9%

270
20.4
34.7
14.5%
0.2%
540
20.4%

271
18.9
35.3
14.9%
−0.1%
530
22.9%

272
18.5
35.5
14.3%
0.4%
540
21.6%

273
17.9
34.6
14.5%
−0.1%
600
20.8%

274
19.6
34.8
13.4%
0.4%
560
21.2%

275
19.9
34.9
14.0%
−0.2%
660
20.3%

276
18.7
34.9
14.2%
0.2%
620
20.4%

277
20.1
35.1
14.1%
0.0%
650
18.4%

278
20.0
34.7
14.1%
0.2%
600
21.5%

279
18.7
34.7
15.3%
−0.4%
590
19.2%

280
19.7
34.5
14.7%
0.3%
570
18.2%

281
19.4
35.3
14.6%
0.2%
580
17.0%

282
17.7
34.8
15.2%
0.0%
580
18.7%

283
19.5
34.8
14.3%
0.5%
590
17.9%

284
17.7
35.0
14.6%
0.5%
570
21.4%

285
17.1
35.4
14.9%
0.3%
590
18.5%

286
20.3
34.6
14.8%
−0.5%
590
21.5%

287
21.5
35.0
13.3%
0.5%
570
19.9%

288
20.4
35.3
14.2%
−0.4%
700
17.5%

289
19.1
35.1
14.5%
−0.2%
640
20.7%

290
18.9
35.3
14.0%
0.5%
650
21.7%

291
19.3
35.3
14.1%
0.2%
650
19.6%

In any of respective examples shown in Table 9B to Table 9G, an improvement rate of the core loss became 15% or more while maintaining good DC bias characteristics. From the results in Experiment 9, it could be understood that the particle composition of the first large particles and the second large particles can be arbitrarily selected without a particular limitation.

EXPLANATIONS OF LETTERS OR NUMERALS

- 2 MAGNETIC CORE
- 10 METAL MAGNETIC PARTICLE
- 10a FIRST PARTICLE GROUP
- 11 LARGE PARTICLE
- 11a FIRST LARGE PARTICLE
- 11b SECOND LARGE PARTICLE
- 4 INSULATION COATING OF LARGE PARTICLE
- 4a INSULATION COATING OF FIRST LARGE PARTICLE
- 4b INSULATION COATING OF SECOND LARGE PARTICLE
- 10b SECOND PARTICLE GROUP
- 12 SMALL PARTICLE
- 12a FIRST SMALL PARTICLE
- 12b SECOND SMALL PARTICLE
- 6 INSULATION COATING OF SMALL PARTICLE
- 6a FIRST INSULATION COATING
- 6b SECOND INSULATION COATING
- 13 MEDIUM PARTICLE
- 20 RESIN
- 60 POWDER TREATMENT DEVICE
- 61 CHAMBER
- 62 BLADE
- 63 MIXTURE
- 100 MAGNETIC COMPONENT
- 5 COIL
- 5a END PORTION
- 5b END PORTION
- 7, 9 EXTERNAL ELECTRODE