JP2021027326A - Soft magnetic metal powder and electronic component - Google Patents

Abstract

To provide soft magnetic metal powder having a high withstand voltage.SOLUTION: Soft magnetic metal powder comprises a plurality of soft magnetic metal particles 1. The soft magnetic metal particles 1 each include a metal particle 2 and an oxide part 3 coating the metal particle 2. The metal particle 2 contains at least Fe. The oxide part 3 contains oxide of at least one element selected from a group consisting of Fe, Si and B, and at least one element of Ca and Mg. As to concentrations of Ca or Mg in the metal particle 2 and the oxide part 3, there is a maximum in the oxide part 3. The maximum value of the concentration of Ca or Mg in the oxide part 3 is 0.2 atom % or larger on average.SELECTED DRAWING: Figure 1

Description

The present invention relates to a soft magnetic metal powder and an electronic component containing the soft magnetic metal powder.

Electronic components such as inductors, transformers and choke coils are often used in power supply circuits of various electronic devices. These electronic components include a coil and a magnetic core located inside the coil. In recent years, as a material for a magnetic core, soft magnetic metal powder is often used instead of conventional ferrite. Compared to ferrite, soft magnetic metal powder has higher saturation magnetization (saturation magnetic flux density) and excellent DC superimposition characteristics (large DC superimposition allowable current), making it suitable for miniaturization of electronic components (magnetic cores). Because there is. (See Patent Document 1 below.)

However, when the soft magnetic metal powder is used for the magnetic core, an eddy current is likely to be generated in the magnetic core due to the conduction between the plurality of soft magnetic metal particles contained in the soft magnetic metal powder. That is, when soft magnetic metal powder is used for the magnetic core, core loss (eddy current loss) is likely to occur. Due to the core loss, the efficiency of the power supply circuit is reduced and the power consumption of the electronic device is increased. Therefore, it is necessary to reduce the core loss. In order to reduce core loss, electrical insulation between soft magnetic metal particles is required. (See Patent Document 2 below.) In other words, a high withstand voltage is required for the soft magnetic metal powder in order to reduce the core loss.

Japanese Patent No. 3342767 JP-A-2017-34228

An object of the present invention is to provide a soft magnetic metal powder having a high withstand voltage and an electronic component containing the soft magnetic metal powder.

The soft magnetic metal powder according to one aspect of the present invention contains a plurality of soft magnetic metal particles, and the soft magnetic metal particles include metal particles and an oxide part covering the metal particles. , At least Fe, and the oxide part contains an oxide of at least one element selected from the group consisting of Fe, Si and B, and at least one element of Ca and Mg in the metal particles and the oxide part. The concentration of Ca or Mg is maximum in the oxidized portion, and the average value of the maximum value of the concentration of Ca or Mg in the oxidized portion is 0.2 atomic% or more.
The average value of the maximum value of the Ca concentration in the oxidized portion may be 10.0 atomic% or less, and the average value of the maximum value of the Mg concentration in the oxidized portion may be 2.0 atomic% or less.

The concentration of Ca or Mg in the oxidized portion may be maximum in the outermost region of the oxidized portion.

At least a part of the metal particles may be in an amorphous phase.

At least a part of the metal particles may be a nanocrystal phase.

The soft magnetic metal particles may further include a coating covering the oxidized portion.

At least one element of Ca and Mg may be present at the interface between the oxidized portion and the coated portion.

The coating may include glass.

The electronic component according to one aspect of the present invention includes the above-mentioned soft magnetic metal powder.

According to the present invention, a soft magnetic metal powder having a high withstand voltage and an electronic component containing the soft magnetic metal powder are provided.

FIG. 1 is a schematic cross-sectional view of soft magnetic metal particles according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the soft magnetic metal particles according to another embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a gas atomizing apparatus used for producing soft magnetic metal powder. FIG. 4 shows an enlarged cross section of a part (cooling water introduction portion) of the apparatus shown in FIG. FIG. 5 shows the concentration distribution of each element in the direction perpendicular to the outermost surface of the oxidized portion of the soft magnetic metal particles.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, equivalent components are labeled with equivalent reference numerals. The present invention is not limited to the following embodiments.

(Soft magnetic metal powder)
The soft magnetic metal powder according to the present embodiment contains a plurality of soft magnetic metal particles. The soft magnetic metal powder can be paraphrased as a whole of a large number of soft magnetic metal particles. As shown in FIG. 1, the soft magnetic metal particle 1 includes a metal particle 2 and an oxidized portion 3 covering the metal particle 2. The soft magnetic metal particles 1 may consist of only the metal particles 2 and the oxidized portion 3. The oxidized portion 3 may be paraphrased as an oxide layer. The oxidized portion 3 may be a natural oxide film. The electrical resistance (electric resistivity) of the oxidized portion 3 itself is higher than the electrical resistance (electric resistivity) of the metal particles 2 themselves. In other words, the oxidized portion 3 has an electrical insulating property. Since the plurality of soft magnetic metal particles 1 come into contact with each other via the oxide portion 3 having an electrically insulating property, the conduction of the soft magnetic metal particles 1 is suppressed and the withstand voltage of the soft magnetic metal powder is increased. That is, the soft magnetic metal powder has a withstand voltage due to the electrical insulating property of the oxidized portion 3. The oxidized portion 3 may cover a part or the whole of the metal particles 2. Since the withstand voltage of the soft magnetic metal powder tends to increase, it is preferable that the oxidized portion 3 covers the entire metal particles 2. The oxidized portion 3 may be interrupted in some places. Since the withstand voltage of the soft magnetic metal powder tends to increase, it is preferable that all the soft magnetic metal particles 1 contained in the soft magnetic metal powder include the metal particles 2 and the oxidized portion 3. However, the soft magnetic metal powder may contain a small number of metal particles that do not contain the oxidized portion 3 as long as the withstand voltage of the soft magnetic metal powder is not impaired. Details of the composition of the oxidized portion 3 will be described later.

As shown in FIG. 2, the soft magnetic metal particles 1 may further include a covering portion 4 covering the oxidized portion 3 in addition to the metal particles 2 and the oxidized portion 3. The electrical resistance (electric resistivity) of the covering portion 4 itself is higher than the electrical resistance (electric resistivity) of the metal particles 2 themselves. In other words, the covering portion 4 has an electrical insulating property. Since the plurality of soft magnetic metal particles 1 come into contact with each other via the coating portion 4 having an electrically insulating property, the conduction of the soft magnetic metal particles 1 is further suppressed, and the withstand voltage of the soft magnetic metal powder is further increased. To do. The covering portion 4 may cover a part or the whole of the oxidized portion 3. Since the withstand voltage of the soft magnetic metal powder tends to increase, it is preferable that the covering portion 4 covers the entire oxidized portion 3. When a part of the metal particles 2 is exposed without being covered by the oxidized portion 3, the covering portion 4 may directly cover a part of the metal particles 2. The coating portion 4 may be composed of a plurality of coating layers different from each other in composition, and the plurality of coating layers may be laminated in a direction perpendicular to the outermost surface of the oxide portion 3. The outermost surface of the oxidized portion 3 is a surface of the oxidized portion 3 that is not in contact with the metal particles 2. The covering portion 4 may be a single layer having a uniform composition.

The covering portion 4 may include glass. The covering portion 4 may be made of only glass. Since the covering portion 4 contains glass, the electrical insulating property of the covering portion 4 is likely to be improved, and the withstand voltage of the soft magnetic metal powder is likely to increase. Further, since the coating portion 4 contains glass, friction and aggregation between the soft magnetic metal particles 1 are likely to be suppressed, the bulk density and filling rate of the soft magnetic metal powder are likely to increase, and the relative permeability of the entire soft magnetic metal powder is likely to increase. Permeability tends to increase. However, the composition of the covering portion 4 is not limited to glass. Details of the composition of the covering portion 4 will be described later.

The "coated particles" described below mean the soft magnetic metal particles 1 provided with the coated portion 4. The "uncoated particles" described below mean soft magnetic metal particles 1 that do not have a coated portion 4.

The soft magnetic metal powder may contain both coated and uncoated particles. The higher the ratio of the number of coated particles to the soft magnetic metal powder, the higher the withstand voltage of the soft magnetic metal powder. The ratio of the number of coated particles to the soft magnetic metal powder may be 90% or more and 100% or less, and 95% or more and 100% or less. Since the withstand voltage of the soft magnetic metal powder tends to increase, the soft magnetic metal powder may consist of only coated particles. However, the soft magnetic metal powder may consist only of uncoated particles.

The metal particles 2 contain at least Fe (iron). The metal particles 2 may be composed of Fe only. The metal particles 2 may contain an alloy containing Fe. The metal particles 2 may consist only of an alloy containing Fe. The soft magnetic magnetism of the soft magnetic metal powder is due to the composition of the metal particles 2. Soft magnetic magnetism means, for example, high relative permeability, high saturation magnetization, and low coercive force. Details of the composition of the metal particles 2 will be described later.

The oxidized portion 3 contains an oxide of at least one element selected from the group consisting of Fe, Si (silicon) and B (boron). This oxide may be the main component of the oxidized portion 3. The oxidized portion 3 further contains at least one element of Ca (calcium) and Mg (magnesium). For example, the oxidized portion 3 may contain an oxide of at least one element of Ca and Mg. Since the oxidized portion 3 has the above composition, the oxidized portion 3 can have excellent electrical insulating properties. As a result, the soft magnetic metal powder can have a high withstand voltage. The oxidized portion 3 may contain only Fe among Fe, Si and B. The oxidized portion 3 may contain only Si among Fe, Si and B. The oxidized portion 3 may contain only B out of Fe, Si and B. The oxidized portion 3 may contain only Fe and Si among Fe, Si and B. The oxidized portion 3 may contain only Si and B among Fe, Si and B. The oxidized portion 3 may contain only B and Fe among Fe, Si and B. The oxidized portion 3 may contain all of Fe, Si and B. The oxidized portion 3 may contain only Ca among Ca and Mg. The oxidized portion 3 may contain only Mg among Ca and Mg. The oxidized portion 3 may contain both Ca and Mg. The oxide contained in the oxidized portion 3 may be a composite oxide containing two or more kinds of elements selected from the group consisting of Fe, Si, B, Ca and Mg. The oxidized portion 3 may further contain elements other than Fe, Si, B, Ca and Mg. For example, the oxidized portion 3 may further contain a Group 1 element (or alkali metal) such as Li (lithium), Na (sodium) and K (potassium). The oxidized portion 3 may further contain a Group 2 element (or alkaline earth metal) such as Be (beryllium), Sr (strontium) and Ba (barium).

The concentration of Ca or Mg in the metal particles 2 and the oxidized portion 3 is maximum in the oxidized portion 3. That is, the concentration distribution of Ca or Mg in the metal particles 2 and the oxidized portion 3 is not uniform, and has a maximum value in the oxidized portion 3. The unit of the concentration of Ca and Mg in the metal particle 2 and the oxidized portion 3 is atomic%. Of the metal particles 2 and the oxidized portion 3, only the oxidized portion 3 may contain at least one element of Ca and Mg. Both the metal particles 2 and the oxidized portion 3 may contain at least one element of Ca and Mg. The concentration of Ca in the metal particles 2 and the oxidized portion 3 may be the maximum in the oxidized portion 3, and the concentration of Mg in the metal particles 2 and the oxidized portion 3 may also be the maximum in the oxidized portion 3. The maximum value of the Ca concentration in the oxidized portion 3 may be the maximum value of the Ca concentration in the oxidized portion 3 and the metal particles 2. The maximum value of the Mg concentration in the oxidized portion 3 may be the maximum value of the Mg concentration in the oxidized portion 3 and the metal particles 2. The average value of the maximum value of the concentration of Ca or Mg in the oxidized portion 3 is 0.2 atomic% or more. The [Ca] described below means the average value of the maximum values of the Ca concentration in the oxidized portion 3. The [Mg] described below means the average value of the maximum values of the Mg concentration in the oxidized portion 3. Since the withstand voltage of the soft magnetic metal powder tends to increase, it is preferable that the concentration of Ca or Mg is maximum in the oxidized portion 3 of all the soft magnetic metal particles 1 contained in the soft magnetic metal powder. However, as long as the withstand voltage of the soft magnetic metal powder is not impaired, the soft magnetic metal powder may contain a small number of metal particles in which the concentration of Ca or Mg is maximum in the portion other than the oxidized portion 3.

Only one of [Ca] and [Mg] may be 0.2 atomic% or more, and both [Ca] and [Mg] may be 0.2 atomic% or more. Since [Ca] or [Mg] is 0.2 atomic% or more, the soft magnetic metal powder can have a high withstand voltage. That is, the withstand voltage of the soft magnetic metal powder in which [Ca] or [Mg] is 0.2 atomic% or more is less than 0.2 atomic% in both [Ca] and [Mg]. Significantly higher than withstand voltage.

The "V1" described below means the withstand voltage of the soft magnetic metal powder composed of only uncoated particles. The "V2" described below means the withstand voltage of the soft magnetic metal powder containing the coated particles. The unit of each of V1 and V2 is V / mm. The "ΔV" described below means V2-V1.

When [Ca] or [Mg] is 0.2 atomic% or more, V2 is high. That is, when [Ca] or [Mg] is 0.2 atomic% or more, the soft magnetic metal powder containing the coated particles can have a high withstand voltage. Further, when [Ca] or [Mg] is 0.2 atomic% or more, ΔV is high. That is, when [Ca] or [Mg] is 0.2 atomic% or more, the amount of increase in the withstand voltage of the soft magnetic metal particles 1 due to the formation of the covering portion 4 is large. When [Ca] or [Mg] is 0.2 atomic% or more, the coating portion 4 easily adheres to the outermost surface of the oxide portion 3, and V2 and ΔV increase remarkably due to the adhesion of the coating portion 4. The inventors speculate.
Further, when [Ca] is larger than 10.0 atomic%, V1 becomes smaller. Even when [Mg] is larger than 2.0 atomic%, V1 becomes smaller. If [Ca] or [Mg] is too large, the shape of the oxidized portion 3 containing at least one element of Ca and Mg becomes non-uniform, and it is difficult for the oxidized portion 3 to uniformly cover the metal particles 2, so that V1 Is thought to be smaller.
Further, when [Ca] is larger than 10.0 atomic%, V2 and ΔV become smaller. When [Mg] is larger than 2.0 atomic%, V2 and ΔV become smaller. When [Ca] or [Mg] is too large, the shape of the oxidized portion 3 containing at least one element of Ca and Mg becomes non-uniform, and the coated portion 4 uniformly covers the metal particles 2 and the oxidized portion 3. Since it is difficult, it is considered that V2 and ΔV become small.

[Ca] and [Mg] may be measured by the following line analysis.

Twenty soft magnetic metal particles 1 are randomly selected from the soft magnetic metal powder. The concentration distributions of Ca and Mg in the metal particles 2 and the oxidized portion 3 of each soft magnetic metal particle 1 are measured. Based on the measured concentration distribution, the maximum value of each concentration of Ca and Mg is specified. The concentration distributions of Ca and Mg are measured in the cross section of the soft magnetic metal particles 1 in the direction perpendicular to the outermost surface of the oxidized portion 3. That is, the concentration distributions of Ca and Mg are measured along the direction perpendicular to the outermost surface of the oxidized portion 3. The direction perpendicular to the outermost surface of the oxidized portion 3 is the depth direction d shown in FIG. Therefore, the concentration distributions of Ca and Mg can be rephrased as the concentration distributions of Ca and Mg along the line segment extending in the depth direction d. The line segment extending in the depth direction d may be a line segment connecting the center of the metal particle 2 and the outermost surface of the oxidized portion 3. The line segment extending in the depth direction d may be a line segment that traverses the entire metal particle 2 and the oxidized portion 3. The means for measuring the concentration distributions of Ca and Mg may be energy dispersive X-ray analysis (EDS). The cross section analyzed by EDS may be observed, for example, by a scanning transmission electron microscope (STEM).

The average value of the maximum value of the Ca concentration is calculated from the maximum value of the Ca concentration measured in the 20 soft magnetic metal particles 1 by the above method. From the maximum value of the Mg concentration measured in the 20 soft magnetic metal particles 1 by the above method, the average value of the maximum value of the Mg concentration is calculated. The concentration distribution of other elements contained in the soft magnetic metal particles 1 may be measured by the same method as the concentration distributions of Ca and Mg, respectively.

[Ca] is 0.2 atomic% or more and 10.0 atomic% or less, 0.2 atomic% or more and 9.0 atomic% or less, 0.2 atomic% or more and 8.0 atomic% or less, 0.2 atomic% or more. 7.0 atom% or less, 0.2 atom% or more and 6.0 atom% or less, 0.2 atom% or more and 5.0 atom% or less, 0.2 atom% or more and 4.0 atom% or less, 0.2 atom It may be% or more and 3.0 atomic% or less, 0.2 atomic% or more and 2.0 atomic% or less, or 0.2 atomic% or more and 1.0 atomic% or less. [Mg] may be 0.2 atomic% or more and 2.0 atomic% or less, 0.2 atomic% or more and 1.0 atomic% or less, or 0.2 atomic% or more and 0.8 atomic% or less. When [Ca] or [Mg] is within any of the above ranges, the soft magnetic metal powder tends to have both excellent soft magnetic properties and high withstand voltage.

The concentration of Ca or Mg in the oxidized portion 3 of each soft magnetic metal particle 1 may be maximum in the outermost surface region 3a of the oxidized portion 3. Due to the maximum concentration of Ca or Mg in the outermost surface region 3a of the oxidized portion 3, the covering portion 4 tends to adhere to the outermost surface of the oxidized portion 3, and V2 and ΔV tend to increase. For the same reason, at least one element of Ca and Mg may be present at the interface between the oxidized portion 3 and the coated portion 4. Even when there is no coated portion 4, the soft magnetic metal powder (uncoated particles) tends to have a high V1 due to the maximum concentration of Ca or Mg in the outermost surface region 3a of the oxidized portion 3. .. The outermost surface region 3a of the oxidized portion 3 may be a region of the oxidized portion 3 in which the distance from the outermost surface of the oxidized portion 3 is within 5 nm. The outermost surface region 3a of the oxidized portion 3 may be a region of the oxidized portion 3 in which the distance from the outermost surface of the oxidized portion 3 is within 2 nm.

At least a part of the metal particles 2 may be an amorphous phase. The metal particles 2 may consist of only an amorphous phase. That is, the entire metal particle 2 may have an amorphous phase. The soft magnetic metal particles 1 containing an amorphous phase are superior in soft magnetic properties to conventional soft magnetic metal particles composed of a coarse crystal phase. For example, the soft magnetic metal particles 1 containing an amorphous phase can have higher saturation magnetization and lower coercive force than conventional soft magnetic metal particles. The coarse crystal phase contained in the conventional soft magnetic metal particles is, for example, a crystal having a grain size or a crystallite diameter larger than 30 nm. As the volume ratio of the amorphous phase to the metal particles 2 increases, the crystal magnetic anisotropy of the soft magnetic metal particles 1 is reduced, and the magnetic loss (hysteresis loss) of the magnetic core formed from the soft magnetic metal particles 1 is reduced. Is reduced.

At least a part of the metal particles 2 may be in a crystalline phase. The entire metal particle 2 may be in a crystalline phase. The metal particles 2 may contain both a crystalline phase and an amorphous phase. At least a part of the metal particles 2 may be a nanocrystal phase. The nanocrystal may be a crystal of Fe alone or a crystal of an alloy containing Fe. The entire metal particle 2 may be a nanocrystal phase. The soft magnetic metal particles 1 containing the nanocrystal phase are superior in soft magnetic properties to the soft magnetic metal particles containing the amorphous phase without containing the nanocrystal phase. For example, the soft magnetic metal particles 1 containing the nanocrystal phase can have higher saturation magnetization and lower coercive force than the soft magnetic metal particles containing the amorphous phase without the nanocrystal phase. The metal particle 2 may include a plurality of nanocrystal phases. The metal particles 2 may consist of only a plurality of nanocrystal phases. The metal particles 2 may consist of only one nanocrystal phase. The crystal structure of the nanocrystal phase may be, for example, a body-centered cubic lattice structure. The particle size (average crystallite diameter) of the nanocrystal phase may be, for example, 5 nm or more and 30 nm or less.

Since the soft magnetic metal powder tends to have excellent soft magnetic properties, the metal particles 2 preferably contain at least one of an amorphous phase and a nanocrystal phase. For the same reason, the metal particles 2 may contain both an amorphous phase and a nanocrystalline phase. For example, the metal particles 2 may have a nanoheterostructure composed of an amorphous phase and a plurality of nanocrystal phases dispersed in the amorphous phase. When the metal particles 2 have a nanoheterostructure, the saturation magnetization of the soft magnetic metal powder tends to increase, and the coercive force of the soft magnetic metal powder tends to decrease. The particle size (average crystallite diameter) of the nanocrystal phase contained in the nanoheterostructure may be, for example, 5 nm or more and 30 nm or less, or 0.3 nm or more and 10 nm or less.

The metal particles 2 do not have to contain an amorphous phase and a nanocrystal phase. For example, part or all of the metal particles 2 may be one or more coarse crystal phases.

In addition to Fe, the metal particles 2 include Nb (niobium), Hf (hafnium), Zr (zirconium), Ta (tantal), Mo (molybdenum) W (tungsten), V (vanadium), B (boron), P. (Rin), Si (silicon), C (carbon), S (sulfur) and Ti (tungsten), Co (cobalt), Ni (nickel), Al (aluminum), Mn (manganese), Ag (silver), Zn Selected from the group consisting of (zinc), Sn (tin), As (arsenic) Sb (antimony), Cu (copper), Cr (chromium), Bi (bismus), N (nitrogen), O (oxygen) and rare earth elements. It may be an alloy containing at least one element.

The metal particles 2 may contain an alloy represented by the following chemical formula 1. The metal particles 2 may consist only of an alloy represented by the following chemical formula 1.
(Fe _{(1- (α + β))} X1 _α X2 _β ) _(1-h) M _a B _b P _c S _d C _{e S f} (1)

B in the above chemical formula 1 is boron. P in the above chemical formula 1 is phosphorus. Si in the above chemical formula 1 is silicon. C in the above chemical formula 1 is carbon. S in the above chemical formula 1 is sulfur. H in the above chemical formula 1 is equal to a + b + c + d + e + f. h is greater than 0 and less than 1.

M in the above chemical formula 1 is at least one element selected from the group consisting of Nb, Hf, Zr, Ta, Mo, W, Ti and V.

X1 in the above chemical formula 1 is at least one element selected from the group consisting of Co and Ni.

X2 in the above chemical formula 1 is at least one element selected from the group consisting of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O and rare earth elements. Rare earth elements are Sc (scandium), Y (yttrium), La (lantern), Ce (cerium), Pr (placeodim), Nd (neodym) Pm (promethium), Sm (samarium), Eu (europyum), Gd ( It is at least one element selected from the group consisting of gadolinium), Tb (terbium), Dy (dysprosium), Ho (formium), Er (erbium), Tm (thulium), Yb (ytterbium), and Lu (lutetium). ..

A in the above chemical formula 1 is
0.020 ≤ a ≤ 0.140,
0.040 ≤ a ≤ 0.100, or
0.050 ≤ a ≤ 0.080,
May be met.
When a is too small, coarse crystals having a particle size of more than 30 nm are likely to be precipitated in the metal particles 2 in the process of producing the soft magnetic metal powder, and fine nanocrystal phases are difficult to be precipitated in the metal particles 2. As a result, the coercive force of the soft magnetic metal powder tends to increase. If a is too large, the saturation magnetization of the soft magnetic metal powder tends to decrease.

B in the above chemical formula 1 is
0 ≦ b ≦ 0.20,
0 <b ≤ 0.20,
0.020 ≤ b ≤ 0.20,
0.020 <b ≤ 0.20,
0.025 ≤ b ≤ 0.20,
0.060 ≤ b ≤ 0.15, or
0.080 ≤ b ≤ 0.12,
May be met.
When b is too small, in the process of producing the soft magnetic metal powder, coarse crystals having a particle size of more than 30 nm are likely to be precipitated in the metal particles 2, and fine nanocrystal phases are difficult to be precipitated in the metal particles 2. As a result, the coercive force of the soft magnetic metal powder tends to increase. If b is too large, the saturation magnetization of the soft magnetic metal powder tends to decrease.

C in the above chemical formula 1 is
0 ≦ c ≦ 0.15,
0 <c ≦ 0.15,
0.005 ≤ c ≤ 0.100, or
0.010 ≤ c ≤ 0.100,
May be met.
When c satisfies 0.005 ≦ c ≦ 0.100, the electrical resistivity of the soft magnetic metal powder tends to increase, and the coercive force tends to decrease. If c is too small, the coercive force tends to increase. If c is too large, the saturation magnetization of the soft magnetic metal powder tends to decrease.

D in the above chemical formula 1 is
0 ≦ d ≦ 0.175,
0 ≦ d ≦ 0.155,
0 ≦ d ≦ 0.150,
0 ≦ d ≦ 0.135,
0 ≦ d ≦ 0.100,
0 ≦ d ≦ 0.090,
0 ≦ d ≦ 0.060,
0.001 ≤ d ≤ 0.040, or
0.005 ≤ d ≤ 0.040,
May be met.
When d is within the above range, the coercive force of the soft magnetic metal powder tends to decrease. If d is too large, the coercive force of the soft magnetic metal powder tends to increase.

E in the above chemical formula 1 is
0 ≦ e ≦ 0.150,
0 ≦ e ≦ 0.080,
0 ≦ e ≦ 0.040,
0 ≦ e ≦ 0.035,
0 ≦ e ≦ 0.030 or
0.001 ≤ e ≤ 0.030,
May be met.
When e is within the above range, the coercive force of the soft magnetic metal powder tends to decrease. If e is too large, the coercive force of the soft magnetic metal powder tends to increase.

F in the above chemical formula 1 is
0 ≦ f ≦ 0.030,
0 ≦ f ≦ 0.010,
0 <f ≦ 0.010,
0.001 ≤ f ≤ 0.010, or
0.002 ≤ f ≤ 0.010,
May be met.
When f is within the above range, the coercive force of the soft magnetic metal powder tends to decrease. If f is too large, the coercive force of the soft magnetic metal powder tends to increase. When f is larger than 0 (f is 0.001 or more), the sphericity of each soft magnetic metal particle is high, and the density (filling rate) of the magnetic core produced by compression molding of the soft magnetic metal powder increases. It is easy to increase the relative magnetic permeability of the magnetic core.

1-h in the above chemical formula 1 is
0.6844 ≤ 1-h ≤ 0.9050, or
0.73 ≤ 1-h ≤ 0.95,
May be met.
When 1-h satisfies 0.73 ≦ 1-h ≦ 0.95, it is difficult for coarse crystals having a particle size of more than 30 nm to precipitate in the metal particles 2 in the process of producing the soft magnetic metal powder.

Α and h in the above chemical formula 1 are
0 ≤ α (1-h) ≤ 0.40, or
0.01 ≤ α (1-h) ≤ 0.40,
May be met.

Β and h in the above chemical formula 1 are
0 ≤ β (1-h) ≤ 0.050,
0.001 ≤ β (1-h) ≤ 0.050,
0 ≦ β (1-h) ≦ 0.030, or
0.001 ≤ β (1-h) ≤ 0.030,
May be met.

Α + β in the above chemical formula 1 may satisfy 0 ≦ α + β ≦ 0.50. When α + β is too large, it is difficult for fine nanocrystal phases to precipitate in the metal particles 2.

The composition of the covering portion 4 is not limited as long as the covering portion 4 electrically insulates the soft magnetic metal particles 1 from each other. For example, the covering portion 4 includes P (phosphorus), Si (silicon), Bi (bismuth), Zn (zinc), Na (sodium), Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium). ), B (boron), Al (aluminum), In (indium), C (carbon), Ge (germanium), Pb (lead), As (arsenic), Sb (antimony), O (oxygen), S (sulfur) ), Se (selenium), Te (tellu), F (fluorine), Cl (chlorine), Br (bromine), Ti (titanium), V (vanadium), Cr (chromium), Fe (iron), Cо (cobalt) ), Ni (nickel), Cu (copper), Zr (zirconium), Mo (molybdenum) and W (tungsten) may contain at least one element selected from the group. The covering portion 4 preferably contains a compound containing at least one element A selected from the group consisting of P, Si, Bi and Zn. A compound containing at least one element A selected from the group consisting of P, Si, Bi and Zn is referred to as "Compound A". Compound A may be, for example, a compound containing P. Compound A may be an oxide (preferably oxide glass). These compounds A are likely to bind to the elements (particularly P or Si) contained in the metal particles 2 and the oxidized portion 3. In particular, the compound A easily binds to an element (particularly P or Si) segregated in the amorphous phase of the metal particles 2. As a result, the coating portion 4 easily adheres to the oxide portion 3, and the withstand voltage of the soft magnetic metal powder tends to increase.

Compound A may be the main component of the coating portion 4. In other words, when the total mass of all elements (excluding oxygen) contained in the covering portion 4 is 100 parts by mass, the total mass of element A is 50 parts by mass or more and 100 parts by mass or less, or 60 parts by mass. It may be 100 parts by mass or less. The covering portion 4 may be composed of only the compound A.

When the covering portion 4 contains oxide glass, the oxide glass includes phosphate glass (P ₂ O ₅ glass), bismuth acid glass (Bi ₂ O ₃ glass), and silicate glass (Bi 2 O 3 glass). SiO ₂ based glass), and may be at least one glass selected from the group consisting of borosilicate glass _{(B 2} O 3 -SiO ₂ based glass).

The content of P ₂ O ₅ in the P ₂ O ₅ system glass may be 50% by mass or more and 100% by mass or less. The P ₂ O ₅ series glass may be, for example, P ₂ O ₅ -ZnO-R ₂ O-Al ₂ O ₃ series glass. R, is an alkali metal.

The content of Bi ₂ O ₃ in the Bi ₂ O ₃ system glass may be 50% by mass or more and 100% by mass or less. The Bi ₂ O ₃ system glass may be, for example, a Bi ₂ O ₃ -ZnO-B ₂ O _3- SiO ₂ system glass.

The content of _B 2 _{O 3} in B ₂ O ₃ -SiO ₂ -based glass may be 10 to 90 _mass%, the content of SiO ₂ in B ₂ O 3 -SiO ₂ -based glass, 10 It may be mass% or more and 90 mass% or less. The B ₂ O _3- SiO ₂ system glass may be, for example, BaO-ZnO-B ₂ O _3- SiO _2- Al ₂ O ₃ system glass.

The median diameter (D50) of the soft magnetic metal powder may be, for example, 0.3 μm or more and 100 μm or less. D50 may be specified based on the number-based particle size distribution of the soft magnetic metal powder. The soft magnetic metal powder may be a mixture of two or more kinds of metal powders having different particle sizes or particle size distributions. The particle size and particle size distribution of the soft magnetic metal powder may be adjusted by sieve classification, air flow classification, or the like. The particle size and particle size distribution of the soft magnetic metal powder may be measured by, for example, a laser diffraction / scattering method. Since the bulk density and the relative magnetic permeability of the soft magnetic metal powder are likely to increase, the shape of each soft magnetic metal particle 1 may be substantially spherical. However, the shape of each soft magnetic metal particle 1 is not limited. The thickness of the oxidized portion 3 may be, for example, 1 nm or more and 20 nm or less. The thickness of the covering portion 4 may be, for example, 5 nm or more and 200 nm or less, 5 nm or more and 150 nm or less, or 5 nm or more and 50 nm or less.

The structures, dimensions and compositions of the metal particles 2, the oxide part 3 and the coating part 4 are as follows: scanning transmission electron microscope (STEM), transmission electron microscope (TEM), energy dispersive X-ray analysis (EDS), electron energy loss. It may be analyzed by methods such as spectroscopy (EELS), high-speed Fourier transform (FFT) analysis of TEM images, and powder X-ray diffraction (XRD) method.

(Manufacturing method of soft magnetic metal powder)
The soft magnetic metal powder according to the present embodiment can be produced by a gas atomizing method or a water atomizing method. Since at least one of an amorphous phase and a nanocrystal phase is likely to be formed in the metal particles 2 of the soft magnetic metal particles 1, the soft magnetic metal powder is preferably produced by a gas atomization method. Details of the gas atomization method and the water atomization method are as follows.

[Gas atomization method]
In the gas atomization method, a metal raw material is melted to form a molten metal (molten metal), high-pressure gas is injected into the molten metal to form droplets, and the droplets are rapidly cooled with cooling water to form a soft magnetic metal powder. As will be described later, after the gas atomization method, heat treatment of the soft magnetic metal powder may be further carried out.

The gas atomizing method may be carried out using the gas atomizing apparatus 10 shown in FIG. The gas atomizing device 10 includes a supply unit 20 and a cooling unit 30 arranged below the supply unit 20. The Z-axis direction shown in FIG. 3 is a vertical direction.

The supply unit 20 includes a heat-resistant container 22 and a coil 24 (heating device) arranged around the container 22. As a raw material for the soft magnetic metal powder, the metal raw material is housed in the container 22.

The metal raw material may be a simple substance of a metal such as Fe. The metal raw material may be an alloy. The composition of the metal raw material may be the composition represented by the above chemical formula 1. A mixture of a plurality of metal raw materials may be used. When a plurality of types of metal raw materials are used, each metal raw material may be weighed so that the overall composition of the plurality of types of metal raw materials matches the above chemical formula 1. The metal raw material may contain unavoidable impurities. The content of unavoidable impurities in all metal raw materials may be 0% by mass or more and 0.1% by mass or less. The form of the metal raw material may be, for example, an ingot, a chunk (lump), or a shot (particle).

The metal raw material in the container 22 is heated by the coil 24. As a result, the metal raw material in the container 22 melts into the molten metal 21. The temperature of the molten metal 21 may be adjusted according to the melting point of the metal contained in the metal raw material. The temperature of the molten metal 21 may be, for example, 1200 ° C. or higher and 1500 ° C. or lower.

The molten metal 21 is dropped from the discharge port of the container 22 toward the cooling unit 30. Then, the high pressure gas 26a is injected from the gas nozzle 26 to the molten metal 21. As a result, the molten metal 21 becomes a large number of fine droplets 21a. The droplet 21a moves inside the cylinder 32 of the cooling unit 30 along the high pressure gas 26a. The atmosphere inside the cylinder 32 may be, for example, a vacuum.

The high-pressure gas injected into the molten metal 21 may be, for example, an inert gas or a reducing gas. The inert gas may be, for example, _{at least one gas selected from the group consisting of N 2} (nitrogen), Ar (argon) and He (helium). The reducing gas may be, for example, an ammonia decomposition gas. When the molten metal 21 is made of a metal that is difficult to oxidize, the high pressure gas may be air.

A water stream 50 is formed inside the cylinder 32 because the cooling water is supplied from the introduction portion 36 to the inside of the cylinder 32. The shape of the water stream 50 is an inverted cone. When the droplet 21a collides with the inverted conical water stream 50, the droplet 21a is decomposed into finer droplets. The fine droplets are rapidly cooled by the water stream 50 and solidified. The water flow 50 (cooling water) contains at least one of Ca and Mg. Therefore, when the surface of the fine droplet comes into contact with the water stream 50, at least one of Ca and Mg adheres to the surface of the droplet. Further, the surface of the droplet may be oxidized by the contact between the droplet and the water stream 50. Alternatively, after the metal particles 2 to which at least one of Ca and Mg is attached are formed, the surface of the metal particles 2 may be naturally oxidized in the atmosphere.

A large number of soft magnetic metal particles 1 (uncoated particles) including the oxidized portion 3 and the metal particles 2 covered with the oxidized portion 3 are formed by the rapid cooling of the droplets (and the subsequent natural oxidation) as described above. Will be done.

As described above, by forming the inverted conical water flow 50 inside the tubular body 32, the movement time of the droplet 21a in the air is longer than that in the case where the water flow is formed along the inner wall of the tubular body 32. It will be shortened. That is, the time required for the droplet 21a to reach the water flow 50 from the container 22 is shortened. By shortening the moving time of the droplet 21a in the air, rapid cooling of the droplet 21a is promoted, and an amorphous phase is likely to be formed in the obtained soft magnetic metal particles. Further, by shortening the moving time of the moving droplet 21a in the air, the oxidation of the moving droplet 21a is suppressed. As a result, the droplet 21a is easily decomposed into fine droplets in the water stream 50, and the quality of the obtained soft magnetic metal powder is improved.

The cooling water may be, for example, _{an aqueous solution of CaCO 3} (calcium carbonate). The cooling water may be an aqueous solution of _{MgCO 3 (magnesium carbonate).} The cooling water may be, for example, an aqueous solution of _{CaCO 3} and MgCO _3. The content of CaCO _{3 in} the cooling water may be 800 mg / liter or more and 2500 mg / liter or less, or 1000 mg / liter or more and 2000 mg / liter or less. When the content of CaCO _{3 in} the cooling water is too low, the average value of the maximum value of the concentration of Ca in the oxidized portion 3 tends to be less than 0.2 atomic%. The content of MgCO _{3 in} the cooling water may be 160 mg / liter or more and 500 mg / liter or less, or 200 mg / liter or more and 400 mg / liter or less. If the content of MgCO _{3 in} the cooling water is too low, the average value of the maximum concentration of Mg in the oxidized portion 3 tends to be less than 0.2 atomic%.

The angle formed by the central axis O of the tubular body 32 and the Z-axis direction is represented by θ1. θ1 may be, for example, 0 ° or more and 45 ° or less. When θ1 is 0 ° or more and 45 ° or less, the droplet 21a easily comes into contact with the inverted conical water stream 50.

A discharge unit 34 is provided below the cylinder 32. The cooling water containing the soft magnetic metal powder is discharged from the discharge unit 34 to the outside of the cylinder 32. The cooling water discharged from the discharge unit 34 may be stored in the storage tank, for example. In the storage tank, the soft magnetic metal powder settles to the bottom of the storage tank due to its own weight. As a result, the soft magnetic metal powder is separated from the cooling water.

By quenching the droplet 21a with cooling water in the gas atomization method, an amorphous phase is easily formed in the soft magnetic metal particles 1 (metal particles 2). The amorphousness and shape of the soft magnetic metal particles 1 may be controlled by the temperature of the cooling water supplied to the cooling unit 30 (cylinder 32), the shape of the water flow 50, the flow velocity or the flow rate of the cooling water.

FIG. 4 is an enlarged view of the cooling water introduction portion 36 shown in FIG. In order to form the inverted conical water flow 50 inside the tubular body 32, the flow of cooling water is controlled by the structure of the introduction portion 36.

As shown in FIG. 4, the space surrounded by the frame body 38 is divided into an outer portion 44 and an inner portion 46 by a partition portion 40. The outer portion 44 (outer space portion) is located outside the tubular body 32. The inner portion 46 (inner space portion) is located inside the tubular body 32. The outer portion 44 and the inner portion 46 communicate with each other via the passage portion 42. A single or multiple nozzles 37 communicate with the outer portion 44. The cooling water is supplied from the nozzle 37 to the outer portion 44, and flows from the outer portion 44 to the inner portion 46 via the passage portion 42. A discharge portion 52 is formed below the inner portion 46. The cooling water in the inner portion 46 is supplied from the discharge portion 52 to the inside of the tubular body 32.

The outer peripheral surface of the frame body 38 is a flow path surface 38b that guides the flow of cooling water in the inner portion 46. A convex portion 38a1 is formed at the lower end 38a of the frame body 38. The convex portion 38a1 projects toward the inner wall 33 of the tubular body 32. The surface of the convex portion 38a1 facing the inner portion 46 is the deflection surface 62. The deflection surface 62 is continuous with the flow path surface 38b, and changes the direction of the cooling water that has passed through the flow path surface 38b. A ring-shaped gap is formed between the tip of the convex portion 38a1 and the inner wall 33 of the tubular body 32. This ring-shaped gap corresponds to the cooling water discharge portion 52.

The convex portion 38a1 of the frame body 38 projects toward the inner wall 33 of the tubular body 32, and the width D1 of the discharge portion 52 is narrower than the width D2 of the inner portion 46. With such a structure, the cooling water that has passed through the flow path surface 38b is directed by the deflection surface 62. As a result, the cooling water collides with the inner wall 33 of the cylinder 32 and is reflected inside the cylinder 32.

When the cooling water passes through the above flow path, the cooling water supplied from the discharge portion 52 to the inside of the tubular body 32 becomes an inverted conical water flow 50. When D1 is equal to D2, the cooling water supplied from the discharge portion 52 to the inside of the tubular body 32 flows in parallel with the inner wall 33 of the tubular body 32, so that it is difficult to form an inverted conical water flow 50.

Since the inverted conical water flow 50 is likely to be formed, D1 / D2 may be 1/10 or more and 2/3 or less, preferably 1/10 or more and 1/2 or less.

The cooling water supplied from the discharge unit 52 to the inside of the cylinder 32 may go straight toward the central axis O of the cylinder 32. The inverted conical water flow 50 may be a water flow that swirls around the central axis O without going straight.

In the gas atomizing method, the particle size and particle size distribution of the soft magnetic metal powder may be controlled by the pressure of the high-pressure gas 26a, the dropping amount of the molten metal 21 per unit time, the pressure of the water stream 50, and the like.

After the gas atomization method, heat treatment of the soft magnetic metal powder may be carried out. By heat treatment of the soft magnetic metal powder, nanocrystal phases are likely to be precipitated in the metal particles 2 of the soft magnetic metal particles 1. For example, heat treatment may change part or all of the amorphous phase into a nanocrystalline phase. By the heat treatment, a plurality of nanocrystal phases may be precipitated in the amorphous phase, and a nanoheterostructure may be formed in the metal particles 2. Since the nanocrystal phase is likely to precipitate in the metal particles 2, the soft magnetic metal powder may be heated at a heat treatment temperature of 400 ° C. or higher and 650 ° C. or lower. For the same reason, the time for maintaining the temperature of the soft magnetic metal powder at the heat treatment temperature may be 0.1 hour or more and 10 hours or less. The heat treatment of the soft magnetic metal powder may be carried out in an inert gas. When the heat treatment also oxidizes the surface of the soft magnetic metal particles 1, the heat treatment of the soft magnetic metal powder may be performed in an oxidative atmosphere (for example, the atmosphere). That is, the oxidized portion 3 that covers the metal particles 2 may be formed by the heat treatment. By adjusting the temperature of the high-pressure gas 26a, the pressure of the high-pressure gas 26a, the pressure of the water stream 50, and the like, the precipitation of the nanocrystal phase in the heat treatment can be promoted.

After the gas atomization method, the surface of the oxidized portion 3 of each soft magnetic metal particle 1 (uncoated particles) may be covered with the coated portion 4. The method for forming the coating portion 4 is, for example, at least one method selected from the group consisting of a powder sputtering method, a sol-gel method, a mechanochemical coating method, a phosphate treatment method, a dipping method, and a heat treatment method. You can. For example, when the coating portion 4 is composed of a plurality of coating layers different from each other in composition, the coating portion 4 may be formed by a combination of a plurality of methods.

In the mechanochemical coating method, a mixture (powder) of uncoated particles and a raw material of a coated portion is contained in a container of a powder coating device. By rotating the container, the mixture is compressed between the grinder installed in the container and the inner wall of the container, and frictional heat is generated in the mixture. The frictional heat softens the raw material of the coating. Then, the raw material of the coating portion is fixed to the surface of the coating particles (the surface of the oxide portion 3) by the compression action, so that the coating portion 4 is formed. Friction heat can be controlled by adjusting the rotational speed of the vessel and the distance between the grinder and the inner wall of the vessel. The frictional heat may be controlled according to the composition of the raw material of the coating portion.

[Water atomization method]
Instead of the gas atomizing method described above, a soft magnetic metal powder may be produced by a water atomizing method. In the water atomization method, as in the gas atomization method, a molten metal is formed by melting the metal raw material. A crucible may be used to form the molten metal.

In the water atomization method, the molten metal ejected from the nozzle collides with a high-pressure water stream. As a result, the molten metal becomes a large number of fine droplets, and the fine droplets are rapidly cooled by the water stream and solidified. The water stream contains at least one of Ca and Mg. At least one of Ca and Mg may be contained in the water stream as ions. Then, at least one of Ca and Mg adheres to the surface of the droplet due to the contact between the droplet (molten metal) and the water stream. Further, the surface of the droplet may be oxidized by the contact between the droplet and the water stream. Alternatively, after the metal particles 2 to which at least one of Ca and Mg is attached are formed, the surface of the metal particles 2 may be naturally oxidized in the atmosphere.

A large number of soft magnetic metal particles 1 (uncoated particles) including the oxidized portion 3 and the metal particles 2 covered with the oxidized portion 3 are formed by the rapid cooling of the droplets (and the subsequent natural oxidation) as described above. Will be done.

The composition of the water stream used in the water atomization method may be the same as the composition of the cooling water used in the gas atomization method.

In the water atomization method, the particle size and particle size distribution of the soft magnetic metal powder may be controlled by adjusting the pressure of the water flow, the amount of molten metal ejected per unit time, and the like. The pressure of the water flow may be, for example, 50 MPa or more and 100 MPa or less. The amount of molten metal ejected may be, for example, 1 kg / min or more and 20 kg / min or less.

A heat treatment of the soft magnetic metal powder may be carried out after the water atomization method for the same purpose as the heat treatment performed after the gas atomization method. Since the nanocrystal phase is likely to precipitate in the metal particles 2, the soft magnetic metal powder may be heated at a heat treatment temperature of 350 ° C. or higher and 800 ° C. or lower. For the same reason, the time for maintaining the temperature of the soft magnetic metal powder in the above temperature range may be 0.1 minutes or more and 120 minutes or less.

As in the case of the gas atomization method, after the water atomization method, the surface of the oxidized portion 3 of each soft magnetic metal particle 1 (uncoated particles) may be covered with the coated portion 4.

(Electronic components)
The electronic component according to the present embodiment includes the above-mentioned soft magnetic metal powder. For example, the electronic component may be an inductor, a transformer, a choke coil, and an EMI (ElectroMagnetic Interference) filter. These electronic components may include a coil and a magnetic core located inside the coil. The magnetic core may contain the above-mentioned soft magnetic metal powder. For example, the magnetic core may include a soft magnetic metal powder and a binder. The binder binds a plurality of soft magnetic alloy particles contained in the soft magnetic metal powder to each other. The binder may include, for example, a thermosetting resin such as an epoxy resin. The inside of the coil may be filled with a mixture of soft magnetic metal powder and binder, and the entire coil may be covered with a mixture of soft magnetic metal powder and binder. The electronic component may be a magnetic head or an electromagnetic wave shield.

The present invention will be described in more detail with reference to Examples and Comparative Examples below. However, the present invention is not limited to the following examples.

Soft magnetic metal powders of Samples 1 to 206 were prepared and analyzed by the following methods. However, there are no samples 86 and 97 to 99.

(Composition of metal raw material)
By mixing a plurality of kinds of raw materials at a predetermined ratio, metal raw materials of soft magnetic metal powders of Samples 1-44 and 193-206 were prepared. The composition of each of the metal raw materials of Samples 1-44 and 193-206 is represented by the following chemical formula 1. H in the following chemical formula 1 is equal to a + b + c + d + e + f. In any of Samples 1-44 and 193-206, M in Chemical Formula 1 was Nb. In all of Samples 1 to 44, α, β, d, e and f in Chemical Formula 1 were zero. The values a, b, c and 1-h in Chemical Formula 1 of Samples 1-44 were the values shown in Tables 1 and 2 below. The values a, b, c, d, e and f and 1-h in each of the samples 193 to 206 in Chemical Formula 1 were the values shown in Table 11 below.
(Fe _{(1- (α + β))} X1 _α X2 _β ) _(1-h) M _a B _b P _c S _d C _{e S f} (1)

By mixing a plurality of kinds of raw materials in a predetermined ratio, metal raw materials of soft magnetic metal powders of each of Samples 45 to 56 were prepared. The composition of each of the samples 45 to 56 as a whole of the metal raw material is described in the “Composition” column of Table 3 below.

By mixing a plurality of kinds of raw materials in a predetermined ratio, metal raw materials of soft magnetic metal powders of Samples 57 to 109, 191 and 192 were prepared. The composition of each of the metal raw materials of Samples 57 to 109, 191 and 192 is represented by the above chemical formula 1. In all of Samples 57 to 109, 191 and 192, M in Chemical Formula 1 was Nb. In all of Samples 57 to 109, 191 and 192, α and β in Chemical Formula 1 were zero. Samples 57 to 109, 191 and 192 each of a, b, c, d, e, f and 1-h in the chemical formula 1 are the values shown in Table 4, Table 5, Table 6 or Table 10 below. It was. The composition of each of the metal raw materials of Samples 57, 191 and 192 was the same.

By mixing a plurality of kinds of raw materials in a predetermined ratio, metal raw materials of soft magnetic metal powders of each of Samples 110 to 136 were prepared. The composition of each of the samples 110 to 136 as a whole metal raw material is represented by the above chemical formula 1.
The composition of each of the metal raw materials of Samples 110 to 118 was the same as that of the entire metal raw material of Sample 59 except for the type of element M. The element M in each of the samples 110 to 118 of Chemical Formula 1 is shown in Table 7 below.
The composition of the entire metal raw material of each of Samples 119 to 127 was the same as the composition of the entire metal raw material of Sample 57 except for the type of element M. The element M in each of the samples 119 to 127 of Chemical Formula 1 is shown in Table 7 below.
The composition of each of the metal raw materials of Samples 128 to 136 was the same as that of the entire metal raw material of Sample 63 except for the type of element M. The element M in each of the samples 128 to 136 in Chemical Formula 1 is shown in Table 7 below.

By mixing a plurality of kinds of raw materials in a predetermined ratio, metal raw materials of soft magnetic metal powder of each sample 137 to 190 were prepared. The composition of the entire metal raw material of each of the samples 137 to 190 is represented by the above chemical formula 1.
The metal raw materials of Samples 137 to 142 each contained the element X1 shown in Table 8 below. The α (1-h) in each of the samples 137 to 142 in Chemical Formula 1 was the value shown in Table 8 below.
The metal raw materials of Samples 143 to 174 each contained the element X2 shown in Table 8 or Table 9 below. The β (1-h) in each of the samples 143 to 174 in Chemical Formula 1 was adjusted to the value shown in Table 8 or Table 9 below.
Samples 175 to 190 Each metal raw material contained element X1 and element X2 shown in Table 9 below. The values of α (1-h) and β (1-h) in Chemical Formula 1 of Samples 175 to 190 were the values shown in Table 9 below.
Except for the above items, the composition of the entire metal raw material of Samples 137 to 190 was the same as the composition of the entire metal raw material of Sample 57.

(Atomize method)
In the case of Samples 1 to 11, 193, 194 and 201 to 203, soft magnetic metal powders (uncoated particles) of each sample were prepared by a gas atomization method using the metal raw material of each sample. In the preparation of Samples 1-11, 193, 194 and 201-203, the heat treatment described later was not performed. In the gas atomizing method, the gas atomizing apparatus shown in FIGS. 3 and 4 described above was used. The details of the gas atomization method were as follows.

The metal raw material was housed in the container 22. The metal raw material in the container 22 was heated by high-frequency induction using the coil 24, and the molten metal 21 was obtained. The temperature of the molten metal 21 was 1500 ° C.

After the atmosphere inside the cylinder 32 of the cooling unit 30 was evacuated, the water flow 50 was formed inside the cylinder 32 by supplying the cooling water from the introduction unit 36 to the inside of the cylinder 32. The shape of the water stream 50 was an inverted cone. The pressure of the water stream 50 (pump pressure) was 7.5 MPa. The inner diameter of the tubular body 32 was 300 mm. The ratio of D1 and D2 (D1 / D2) in FIG. 4 was 1/2. The angle θ1 in FIG. 4 was 20 ° C.

_{CaCO 3} (calcium carbonate) was added to the cooling water (water flow 50) in advance. _{The content of CaCO 3} (unit: mg / liter) in the cooling water used for preparing each sample is described in the column _{of "CaCO 3" in the table below.}

The molten metal 21 was dropped from the discharge port of the container 22 toward the cooling unit 30. Then, the high pressure gas 26a was injected from the gas nozzle 26 into the molten metal 21. The high pressure gas 26a was argon gas. The pressure of the high pressure gas 26a was 5 MPa. By injecting the high pressure gas 26a, the molten metal 21 became a large number of fine droplets 21a. The droplet 21a moved to the inside of the cylinder 32 of the cooling unit 30 along the high pressure gas 26a. When the droplet 21a collides with the inverted conical water stream 50 in the cylinder 32, the droplet 21a is decomposed into finer droplets. The fine droplets were rapidly cooled by the water stream 50 and solidified to obtain a soft magnetic metal powder (uncoated particles). The water stream 50 (cooling water) containing the soft magnetic metal powder was discharged from the discharge unit 34 to the outside of the cylinder 32, and the soft magnetic metal powder was recovered from the cooling water.

In the case of Samples 12 to 22, 195, 196 and 204 to 206, a soft magnetic metal powder was obtained by a gas atomization method using a metal raw material of each sample, and then the soft magnetic metal powder was heat-treated. The gas atomization method performed in the preparation of Samples 12-22, 195, 196 and 204-206 was the same as the above method. _{The content of CaCO 3} in the cooling water used to prepare each sample is described in the column of "CaCO _{3" in the table below.} In the heat treatment, the soft magnetic metal powder was heated to 600 ° C. at a heating rate of 5 K / min, and the temperature of the soft magnetic metal powder was maintained at 600 ° C. for 1 hour. In the case of Samples 12-22, 195, 196 and 204-206, the soft magnetic metal powder means a soft magnetic metal powder that has undergone heat treatment.

In the case of Samples 23 to 33, 197 and 198, soft magnetic metal powder (uncoated particles) of each sample was prepared by a gas atomization method using a metal raw material of each sample. In the preparation of Samples 23-33, 197 and 198, the above heat treatment was not performed. In the case of Samples 23 to 33, 197 and 198, MgCO ₃ (magnesium carbonate) was added to the cooling water (water flow 50) in advance instead of _{CaCO 3. The content of MgCO 3} (unit: mg / liter) in the cooling water used for preparing each sample is described in the column _{of "MgCO 3" in the table below.} Except for the composition of the cooling water, the gas atomization method performed in the preparation of Samples 23-33, 197 and 198 was the same as the above method.

In the case of Samples 34 to 44, 199 and 200, the soft magnetic metal powder was obtained by the gas atomization method using the metal raw material of each sample, and then the soft magnetic metal powder was heat-treated. In the case of samples 34 to 44, 199 and 200, MgCO ₃ was added to the cooling water (water flow 50) in advance instead of _{CaCO 3. The content of MgCO 3} in the cooling water used for preparing each sample is described in the column of "MgCO _{3" in the table below.} Except for the composition of the cooling water, the gas atomization method performed in the preparation of Samples 34-44, 199 and 200 was the same as the above method. The method of heat treatment performed in the preparation of Samples 34-44, 199 and 200 was the same as the above method. In the case of Samples 34 to 44, 199 and 200, the soft magnetic metal powder means a soft magnetic metal powder that has undergone heat treatment.

In the case of samples 45 to 48, soft magnetic metal powder (uncoated particles) of each sample was prepared by a gas atomization method using the metal raw material of each sample. The above heat treatment was not performed in the preparation of the samples 45 to 48. In the case of samples 45 to 48, CaCO ₃ and MgCO ₃ were added in advance to the cooling water (water flow 50). _{The content of CaCO 3} in the cooling water used for preparing each sample is described in the column of "CaCO _{3" in the table below. The content of MgCO 3} in the cooling water used for preparing each sample is described in the column of "MgCO _{3" in the table below.} Except for the composition of the cooling water, the gas atomization method performed in the preparation of the samples 45 to 48 was the same as the above method.

In the case of the samples 49 to 52, the soft magnetic metal powder was obtained by the gas atomization method using the metal raw material of each sample, and then the soft magnetic metal powder was heat-treated. In the case of samples 49 to 52, CaCO ₃ and MgCO ₃ were added in advance to the cooling water (water flow 50). _{The content of CaCO 3} in the cooling water used for preparing each sample is described in the column of "CaCO _{3" in the table below. The content of MgCO 3} in the cooling water used to prepare each sample is described in the column of "MgCO _{3" in the table below.} Except for the composition of the cooling water, the gas atomizing method performed in the preparation of the samples 49 to 52 was the same as the above method. The method of heat treatment performed in the preparation of the samples 49 to 52 was the same as the above method. In the case of Samples 49 to 52, the soft magnetic metal powder means a soft magnetic metal powder that has undergone heat treatment.

In the case of samples 53 to 56, soft magnetic metal powder (uncoated particles) of each sample was prepared by a water atomization method using the metal raw material of each sample. The above heat treatment was not performed in the preparation of the samples 53 to 56. The details of the water atomization method were as follows.

The metal raw material was housed in the crucible. The metal raw material in the crucible was heated by high frequency induction using a coil, and a molten metal was obtained. The temperature of the molten metal was 1500 ° C. The molten metal ejected from the nozzle formed below the crucible collided with a high-pressure water stream (cooling water). As a result, the molten metal became a large number of fine droplets. The fine droplets were rapidly cooled by a stream of water and solidified to obtain a soft magnetic metal powder (uncoated particles). The soft magnetic metal powder was recovered from the cooling water.

_{CaCO 3} and MgCO ₃ were added in advance to the cooling water used in the water atomization method. _{The content of CaCO 3} in the cooling water used for preparing each sample is described in the column of "CaCO _{3" in the table below. The content of MgCO 3} in the cooling water used for preparing each sample is described in the column of "MgCO _{3" in the table below.}

In the case of Samples 57 to 192, the soft magnetic metal powder was obtained by the gas atomization method using the metal raw material of each sample, and then the soft magnetic metal powder was heat-treated. In the case of samples 57 to 192, CaCO ₃ and MgCO ₃ were added in advance to the cooling water (water flow 50). _{The content of CaCO 3} in the cooling water used for preparing each sample was 2000 mg / liter. _{The content of MgCO 3} in the cooling water used for preparing each sample was 400 mg / liter. Except for the composition of the cooling water, the gas atomization method performed in the preparation of the samples 57 to 192 was the same as the above method. The method of heat treatment performed in the preparation of the samples 57 to 192 was the same as the above method. In the case of Samples 57 to 192, the soft magnetic metal powder means a soft magnetic metal powder that has undergone heat treatment.

(Analysis of soft magnetic metal powder)
The soft magnetic metal powders (uncoated particles) of Samples 1 to 206 were analyzed by the following methods.

A molded product was obtained by molding a mixture of a soft magnetic metal powder and a thermosetting resin and curing the thermosetting resin. The molded body was processed by ion milling to obtain a thin film (measurement sample). The cross sections of the 20 soft magnetic metal particles contained in the thin film were observed by STEM. The concentration distribution of each element was measured in the cross section of each observed soft magnetic metal particle. The concentration distribution of each element was measured along the direction perpendicular to the outermost surface of each soft magnetic metal particle. That is, as shown in FIG. 1, the concentration distribution of each element was measured along a line segment extending in the depth direction d and crossing the soft magnetic metal particle 1. The interval between measurement points was about 0.5 nm. EDS was used to measure the concentration distribution of each element. The unit of concentration of each element is atomic%. As an example of the concentration distribution, the concentration distribution of each element in the soft magnetic metal particles of the sample 10 is shown in FIG. As shown in FIG. 5, there were peaks (maximum values) of the concentrations of Ca, Si and O respectively. The peaks of the concentrations of Ca, Si and O were measured in the region where the depth from the outermost surface of the soft magnetic metal particles was within about 10 nm. In particular, the peak concentration of Ca was measured in the region where the depth from the outermost surface of the soft magnetic metal particles was within about 2 nm.

As a result of the analysis, the soft magnetic metal particles of Samples 1 to 206 each consisted of metal particles and an oxidized portion covering the entire metal particles. In each of the samples 1 to 206, the composition of the metal particles substantially matched the composition of the entire metal raw material. In each of Samples 1 to 206, the oxide portion contained an oxide of at least one element selected from the group consisting of Fe, Si and B. For example, the oxidized part of each of the samples 201 to 206 was composed of Fe, Si, B, Ca and O. When Ca or Mg was detected in the soft magnetic metal particles, the concentration of Ca or Mg in the uncoated particles was maximum in the oxidized portion. In the case of all examples, the concentration of Ca or Mg in the uncoated particles was maximum in the outermost region of the oxidized portion.

The average value of the maximum value of Ca concentration was calculated from the maximum value of Ca concentration measured in the oxidized portion of each of the 20 soft magnetic metal particles. The average value of the maximum value of the concentration of Ca in the oxidized part of each sample is described in the column of [Ca] in the table below. Ca was not detected in the oxidized part of the sample without the [Ca] column in the table below. In addition, Ca was not detected in the oxidized part of the sample in which zero was described in the column of [Ca] in the table below.

The average value of the maximum value of the Mg concentration was calculated from the maximum value of the Mg concentration measured in the oxidized portion of each of the 20 soft magnetic metal particles. The average value of the maximum value of the concentration of Mg in the oxidized portion of each sample is described in the column of [Mg] in the table below. No Mg was detected in the oxidized part of the sample without the [Mg] column in the table below. Further, in the oxidized part of the sample in which zero was described in the column of [Mg] in the table below, Mg was not detected in the oxidized part.

The X-ray diffraction patterns of Samples 1-56 and 193-206 were measured using a powder X-ray diffractometer. The crystal structures of the soft magnetic metal powders of Samples 1 to 56 and 193 to 206 were analyzed based on the X-ray diffraction patterns of Samples 1 to 56 and 193 to 206 and the observation of each soft magnetic metal particle by STEM. It was. The results are shown in the "Crystal Structure" column of the table below. “Amorphous” described in the “Crystal structure” column means that crystals having a particle size larger than 30 nm are not detected in the soft magnetic metal particles, and diffracted X-rays derived from the body-centered cubic lattice structure are detected. It means that it has become. The "nanocrystal" described in the "crystal structure" column means that the average particle size of the crystals contained in the soft magnetic metal particles is 5 to 30 nm, and diffracted X-rays derived from the body-centered cubic lattice structure are detected. Means that. The "crystal" described in the "crystal structure" column means that a crystal having a particle size larger than 30 nm is detected from the soft magnetic metal particles, and the average particle size of the crystal contained in the soft magnetic metal particle is larger than 30 nm. It means that diffracted X-rays derived from the body-centered cubic lattice structure were detected.

(Measurement of magnetic characteristics)
The coercive force and saturation magnetization of each of the soft magnetic metal powders (uncoated particles) of Samples 1 to 206 were measured by the following methods.

20 g of soft magnetic metal powder (uncoated particles) and paraffin were housed in a tubular plastic case. The inner diameter φ of the plastic case was 6 mm, and the length of the plastic case was 5 mm. A sample for measurement was obtained by melting the paraffin in the plastic case by heating and then coagulating the paraffin. The coercive force and saturation magnetization of this measurement sample were measured. A coercive magnetometer (K-HC1000 type) manufactured by Tohoku Steel Co., Ltd. was used for measuring the coercive force. The measured magnetic field was 150 kA / m. A VSM (vibrating sample magnetometer) manufactured by Tamagawa Seisakusho Co., Ltd. was used for the measurement of saturation magnetization. The coercive force Hc (unit: A / m) of each of Samples 1 to 206 is shown in the table below. ^{The saturation magnetization σs (unit: Am 2} / kg) per unit mass of each of Samples 1 to 206 is shown in the table below. The coercive force Hc is preferably low, and the saturation magnetization σs is preferably high.

(Measurement of withstand voltage of uncoated particles)
The withstand voltage of each of the soft magnetic metal powders (uncoated particles) of Samples 1 to 56 and 193 to 206 was measured by the following method.

A solution was prepared by mixing an epoxy resin (thermosetting resin), an imide resin (curing agent), and acetone. Granules were obtained by mixing the solution with soft magnetic metal powder (uncoated particles) and then volatilizing acetone. The total mass of the epoxy resin and the imide resin was 3 parts by mass with respect to 100 mass of the soft magnetic metal powder. Granules were sized using a mesh. The mesh opening was 355 μm. A molded product was obtained by molding the granules using a toroidal mold. The inner diameter of the mold was 6.5 mm, and the outer diameter of the mold was 11 mm. The molding pressure was 3.0 t / cm ² . The molded product was heated at 180 ° C. for 1 hour to cure the epoxy resin. By the above method, a dust core was obtained.

A voltage was applied to the dust core using a source meter. The current in the dust core was continuously measured while continuously increasing the voltage. The withstand voltage of the dust core is defined as the voltage at the time when the current in the dust core reaches 1 mA. The withstand voltage V1 (unit: V / mm) of each of the soft magnetic metal powders (uncoated particles) of Samples 1 to 56 and 193 to 206 is shown in the table below. V1 is preferably high.

(Formation of covering part)
By the mechanochemical coating method, a coating portion was formed on the entire surface of the uncoated particles (soft magnetic metal powder) of each of Samples 1 to 206. Powdered glass was used as a raw material for the covering portion. That is, the entire oxidized portion of the uncoated particles of Samples 1 to 206 was covered with a coated portion made of glass. The mass of the powdered glass was 0.5 parts by mass with respect to 100 parts by mass of uncoated particles (soft magnetic metal powder). The thickness of the covering portion was about 50 nm.

The powdered glass used to form the coatings of Samples 1-190 and 193-206 was phosphate-based glass. The main component of the phosphate-based glass is represented as P ₂ O ₅ --ZnO-R ₂ O-Al ₂ O ₃ . R is an alkali metal. The content of _P 2 _{O 5} in the phosphate type glass, was 50 wt%. The ZnO content in the phosphate glass was 12% by mass. The content of R _{2 O} in phosphate type glass was 20 wt%. _{The content of Al 2} O ₃ in the phosphate-based glass was 6% by mass. In addition to these four components, 12% by mass of sub-components were contained in the phosphate glass.
The powdered glass used to form the coating of Sample 191 was bismuthate-based glass. The main component of the bismuthate-based glass is represented as _{Bi 2} O _3- ZnO-B ₂ O _3- SiO _{2. The content of Bi 2} O ₃ in the bismuth acid salt-based glass was 80% by mass. The ZnO content in the bismuth acid salt-based glass was 10% by mass. _{The content of B 2} O ₃ in the bismuth acid salt-based glass was 5% by mass. _{The content of SiO 2} in the bismuthate-based glass was 5% by mass.
The powdered glass used to form the coating of Sample 192 was borosilicate glass. The main component of the borosilicate glass is represented as BaO-ZnO-B ₂ O _3- SiO _2- Al ₂ O ₃ . The content of BaO in the borosilicate glass was 8% by mass. The ZnO content in the borosilicate glass was 23% by mass. _{The content of B 2} O ₃ in the borosilicate glass was 19% by mass. _{The content of SiO 2} in the borosilicate glass was 16% by mass. _{Al 2} O ₃ in the borosilicate glass was 6% by mass. The borosilicate-based glass further contained an auxiliary component as a balance other than the above-mentioned main component.
As will be described later, the coated particles of Samples 191 and 192 each had a high V2, similar to the coated particles having phosphate-based glass as a coating portion (Example).

(Measurement of withstand voltage of coated particles)
After the coating portion was formed, the withstand voltage V2 of each of the soft magnetic metal powders (coated particles) of Samples 1 to 206 was measured. The method for measuring the withstand voltage V2 of the coated particles was the same as the method for measuring the withstand voltage V1 of the uncoated particles. The withstand voltage V2 (unit: V / mm) of each of the soft magnetic metal powders (coated particles) of Samples 1 to 206 is shown in the table below. V2 is preferably high.

The ΔVs of Samples 1-56 and 193-206 are shown in the table below. As mentioned above, ΔV is V2-V1. It is preferable that ΔV is high.

All of the samples 57 to 192 shown in Table 4, Table 5, Table 6, Table 7, Table 8, Table 9 or Table 10 are Examples.

The soft magnetic metal powder according to the present invention is suitable, for example, as a material for the magnetic core of an inductor.

1 ... Soft magnetic metal particles, 2 ... Metal particles, 3 ... Oxidized part, 4 ... Coating part.

Claims (9)

A soft magnetic metal powder containing a plurality of soft magnetic metal particles.
The soft magnetic metal particles include metal particles and an oxidized portion that covers the metal particles.
The metal particles contain at least Fe and
The oxidized part
An oxide of at least one element selected from the group consisting of Fe, Si and B, and
At least one element of Ca and Mg,
Including
The concentration of Ca or Mg in the metal particles and the oxidized portion is maximum in the oxidized portion.
The average value of the maximum value of the concentration of Ca or Mg in the oxidized portion is 0.2 atomic% or more.
Soft magnetic metal powder. The average value of the maximum value of the Ca concentration in the oxidized portion is 10.0 atomic% or less.
The average value of the maximum value of the concentration of Mg in the oxidized portion is 2.0 atomic% or less.
The soft magnetic metal powder according to claim 1. The concentration of Ca or Mg in the oxidized portion is maximum in the outermost region of the oxidized portion.
The soft magnetic metal powder according to claim 1 or 2. At least a part of the metal particles is in an amorphous phase.
The soft magnetic metal powder according to any one of claims 1 to 3. At least a part of the metal particles is a nanocrystal phase.
The soft magnetic metal powder according to any one of claims 1 to 4. The soft magnetic metal particles further include a coating portion that covers the oxidized portion.
The soft magnetic metal powder according to any one of claims 1 to 5. At least one element of Ca and Mg is present at the interface between the oxidized portion and the coated portion.
The soft magnetic metal powder according to claim 6. The covering includes glass.
The soft magnetic metal powder according to claim 6 or 7. An electronic component containing the soft magnetic metal powder according to any one of claims 1 to 8.