阅读说明：本技术 压粉材料及旋转电机 (Powder compact material and rotating electrical machine ) 是由 真田直幸 末纲伦浩 木内宏彰 堀田康之 于 2020-08-26 设计创作，主要内容包括：本发明的实施方式的压粉材料是具备多个扁平磁性金属粒子和夹杂相的压粉材料,所述扁平磁性金属粒子具有扁平面和包含选自由Fe、Co及Ni构成的组中的至少1个第一元素的磁性金属相,平均厚度为10nm～100μm,扁平面内的平均长度相对于厚度之比的平均值为5～10000,所述夹杂相存在于扁平磁性金属粒子之间,且包含选自由氧(O)、碳(C)、氮(N)及氟(F)构成的组中的至少1个第二元素,在压粉材料中,在相对于扁平面垂直的规定的截面中,在扁平磁性金属粒子的扁平面与和扁平面相接的夹杂相的边界部包含空隙部位,相对于扁平面的长度的空隙部位的长度的比率为20％以下。(The powder compact according to the embodiment of the present invention is a powder compact including a plurality of flat magnetic metal particles and an inclusion phase, the flat magnetic metal particles have flat surfaces and a magnetic metal phase containing at least 1 first element selected from the group consisting of Fe, Co and Ni, the average thickness is 10nm to 100 [ mu ] m, the average value of the ratio of the average length to the thickness in the flat surfaces is 5 to 10000, the inclusion phase is present between the flat magnetic metal particles, and comprises at least 1 second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N) and fluorine (F), in the powder compact, in a predetermined cross section perpendicular to the flat surface, a void portion is included at a boundary portion between the flat surface of the flat magnetic metal particles and an inclusion phase in contact with the flat surface, and a ratio of a length of the void portion to a length of the flat surface is 20% or less.)

1. A powder compact comprising a plurality of flat magnetic metal particles and an inclusion phase, wherein the flat magnetic metal particles have a flat surface and a magnetic metal phase containing at least 1 first element selected from the group consisting of Fe, Co and Ni, the average thickness is 10nm to 100 [ mu ] m, the average value of the ratio of the average length to the thickness in the flat surface is 5 to 10000, and the inclusion phase is present between the flat magnetic metal particles and contains at least 1 second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N) and fluorine (F),

in the powder compact, in a predetermined cross section perpendicular to the flat surface, a void portion is included at a boundary portion between the flat surface of the flat magnetic metal particles and the inclusion phase in contact with the flat surface, and a ratio of a length of the void portion to a length of the flat surface is 20% or less.

2. The powder compact according to claim 1, wherein the powder compact has a directionally-induced difference in coercive force in a plane.

3. The powder compact according to claim 1, wherein at least a part of the surface of the flat magnetic metal particles is covered with a coating layer having a thickness of 0.1nm to 1 μm and containing at least 1 of the second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N), and fluorine (F).

4. The dust material according to claim 1, wherein the inclusion phase comprises a resin having a weight loss rate of 5% or less after heating at 180 ℃ for 3000 hours.

5. The powder compact according to claim 1, wherein the weight loss ratio of the powder compact after heating at 180 ℃ for 3000 hours is 5% or less.

6. The dust material of claim 1, wherein the inclusion phase comprises a resin having no glass transition temperature below a thermal decomposition temperature.

7. The dust material according to claim 1, wherein the inclusion phase is a polyimide resin.

8. A rotary electric machine comprising the powder compact according to claim 1.

9. A rotating electrical machine provided with a magnetic wedge comprising the dust material according to claim 1.

10. A rotary electric machine provided with a core comprising the dust material according to claim 1.

Technical Field

Embodiments of the present invention relate to a magnetic material and a rotating electrical machine.

Background

Soft magnetic materials are currently used for parts of various systems and devices such as rotating electric machines (e.g., motors, generators), transformers, inductors, inverters, magnetic inks, and antenna devices, and are very important materials. In these components, since the real part of magnetic permeability (real part of relative permeability) μ 'of the soft magnetic material is used, it is preferable to control μ' in comparison with the use frequency band in the case of actual use. In addition, in order to realize a high efficiency system, it is preferable to make a material with as low loss as possible. That is, it is preferable to reduce the imaginary part of magnetic permeability (relative imaginary part of magnetic permeability) μ ″ (corresponding to loss) as much as possible. Regarding the loss, a loss coefficient tan δ (═ μ "/μ '× 100 (%)) is a criterion, and a smaller μ ″ is relative to μ', a smaller loss coefficient tan δ becomes, and thus is preferable. Therefore, it is preferable to reduce the iron loss under the actual operating conditions, that is, to reduce the eddy current loss, the hysteresis loss, the ferromagnetic resonance loss, and the residual loss (other losses) as much as possible. In order to reduce eddy current loss, it is effective to increase the resistance, or to reduce the size of the metal portion, or to subdivide the magnetic domain structure. In order to reduce the hysteresis loss, it is effective to reduce the coercive force or increase the saturation magnetization. In order to reduce the ferromagnetic resonance loss, it is effective to increase the ferromagnetic resonance frequency by increasing the anisotropic magnetic field of the material. In recent years, there has been an increasing demand for electric power having a large power, and therefore, there has been a demand for a low loss under operating conditions in which an effective magnetic field applied to a material is large, such as a high current and a high voltage. Therefore, in order not to cause magnetic saturation, the saturation magnetization of the soft magnetic material is preferably as large as possible. Further, in recent years, as devices can be miniaturized by increasing the frequency, the frequency band of the use band of systems and equipment has been increased, and it is urgent to develop a magnetic material having high magnetic permeability, low loss, and excellent characteristics at high frequencies.

In recent years, awareness of energy saving and environmental issues has increased, and therefore it is required to improve system efficiency as much as possible. In particular, since the motor system consumes a large amount of power in society, it is very important to increase the efficiency of the motor. In particular, the core and the like constituting the motor are made of a soft magnetic material, and it is required to increase the magnetic permeability and saturation magnetization of the soft magnetic material as much as possible or to reduce the loss as much as possible. In addition, a magnetic wedge (magnetic wedge) used in a part of a motor is required to reduce loss as much as possible. The same requirements apply to a system using a converter. In motors, inverters, and the like, there is a great demand for miniaturization as well as for high efficiency. In order to achieve miniaturization, it is important to increase the magnetic permeability and saturation magnetization of the soft magnetic material as much as possible. In addition, in order to prevent magnetic saturation, it is also important to increase saturation magnetization as much as possible. Further, there is a great demand for higher system operating frequencies, and development of materials with low loss at high frequency bands is demanded.

In addition, soft magnetic materials having high magnetic permeability and low loss are also used in inductance elements, antenna devices, and the like, and particularly in recent years, attention has been paid to application to power inductance elements used in power semiconductors. In recent years, importance of energy saving and environmental protection has been actively promoted, and reduction of CO is required₂Emissions and reduced dependence on fossil fuels. As a result, electric vehicles and hybrid vehicles, which replace gasoline vehicles, have been developed to the utmost. Further, a technology for utilizing natural energy such as solar power generation and wind power generation is called a key technology of an energy-saving society, and development of a technology for utilizing natural energy is actively conducted in advanced countries. Further, as an environmentally friendly power saving System, importance of a Home Energy Management System (HEMS) and a Building and Energy Management System (BEMS) for constructing a smart grid for controlling power generated by solar power generation, wind power generation, or the like and supplying power to and from a Home, an office, and a factory with high efficiency has been actively promoted. In such a power saving flow, the power semiconductor plays an important role. The power semiconductor is a semiconductor for controlling high power and energy with high efficiency, and includes Insulated Gate Bipolar Transistors (IGBTs), MOSFETs, and power bipolar transistorsPower supply circuits such as linear regulators and switching regulators, and power management logic LSIs for controlling these components are included in addition to power individual semiconductors such as transistors and power diodes. Power semiconductors are widely used in all instruments such as home appliances, computers, automobiles, and railways, and the popularization of these instruments and the mounting ratio of power semiconductors in these instruments are expected to expand, so that the market growth of power semiconductors is expected to grow in the future. For example, in inverters mounted in many household electrical appliances, it can be said that a power semiconductor is basically used, and thus significant energy saving can be achieved. For power semiconductors, Si is currently the mainstream, but SiC and GaN are considered to be effective for further improvement in efficiency and miniaturization of devices. SiC and GaN have larger band gaps and larger dielectric breakdown fields than Si, and can improve withstand voltage, so that the element can be made thinner. Therefore, the on-resistance of the semiconductor can be reduced, which is effective for reducing the loss and increasing the efficiency. Further, SiC and GaN have high carrier mobility, and therefore, the switching frequency can be increased, which is effective for downsizing the device. Further, SiC in particular has high thermal conductivity compared to Si, so that it has high heat release capability, can operate at high temperature, can simplify the cooling mechanism, and is effective for miniaturization. From the above-described viewpoints, SiC and GaN power semiconductors have been developed as much as possible. However, in order to realize the development thereof, it is essential to develop a power inductor element used together with a power semiconductor, that is, a high-permeability soft magnetic material (high permeability and low loss). In this case, as characteristics required for the magnetic material, high magnetic permeability and low magnetic loss in the drive frequency band are preferable, and high saturation magnetization capable of handling a large current is also preferable. When the saturation magnetization is high, even if a high magnetic field is applied, magnetic saturation is not easily caused, and a decrease in effective inductance value can be suppressed. This improves the dc superimposition characteristics of the device, and improves the system efficiency.

Magnetic materials having high magnetic permeability and low loss at high frequencies are expected to be applied to devices of high-frequency communication equipment such as antenna devices. As a method for reducing the size and power consumption of an antenna, there is a method of transmitting and receiving a signal by using an insulating substrate having a high magnetic permeability (high magnetic permeability and low loss) as an antenna substrate and winding a radio wave that reaches an electronic component or a substrate in a communication device from the antenna so that the radio wave does not reach the electronic component or the substrate. This is preferable because the antenna can be miniaturized and power-saving, and the resonance frequency of the antenna can be widened.

As other characteristics required when the system and the device are incorporated, high thermal stability, high strength, high toughness, and the like can be mentioned. In addition, in order to be applied to a complicated shape, a pressed powder is more preferable than a plate or a belt. However, it is known that, when a powder compact is prepared, the properties are deteriorated in terms of saturation magnetization, magnetic permeability, loss, strength, toughness, hardness, and the like, and it is preferable to improve the properties.

Next, the kind and problems of the conventional soft magnetic material will be described.

As a conventional soft magnetic material for a system of 10kH or less, a silicon steel plate (FeSi) is exemplified. Silicon steel sheets have a long history and are used as core materials for rotating electrical machines and inverters which handle large electric power. The present inventors have found that the characteristics of a non-oriented silicon steel sheet are improved to a grain-oriented silicon steel sheet, and the improvement of the characteristics is maximized in recent years. As characteristics, it is particularly important to satisfy high saturation magnetization, high magnetic permeability, and low loss at the same time. In the society, studies on materials exceeding silicon steel sheets are actively being conducted mainly on amorphous-system and nanocrystalline-system compositions, and the compositions exceeding silicon steel sheets have not yet been found in all aspects. In addition, studies have been made to be applicable to a green compact having a complicated shape, and the green compact has a disadvantage of inferior properties as compared with a plate or a tape.

Conventional soft magnetic materials for systems of 10kHz to 100kHz include Fe-Si-Al alloy (Fe-Si-Al), nanocrystalline Finemet (Fe-Si-B-Cu-Nb), Fe-based or Co-based amorphous/glass ribbon/compact, and MnZn-based ferrite materials. However, they have not fully satisfied the requirements of high magnetic permeability, low loss, high saturation magnetization, high thermal stability, high strength, high toughness, and high hardness, and are not sufficient.

Conventional soft magnetic materials having a frequency of 100kHz or higher (MHz band or higher) include NiZn ferrite and hexagonal ferrite, but have insufficient magnetic properties at high frequencies.

In view of the above, it is preferable to develop a magnetic material having high saturation magnetization, high magnetic permeability, low loss, high thermal stability, and excellent mechanical properties.

Disclosure of Invention

The present invention addresses the problem of providing a powder compact material having excellent magnetic properties, and a rotating electrical machine using the same.

The powder compact of the embodiment is a powder compact including a plurality of flat magnetic metal particles and an inclusion phase, the plurality of flat magnetic metal particles have flat surfaces and a magnetic metal phase containing at least 1 first element selected from the group consisting of Fe, Co and Ni, an average thickness is 10nm to 100 [ mu ] m, an average value of a ratio of an average length in the flat surfaces to the thickness is 5 to 10000, the inclusion phase is present between the flat magnetic metal particles, and comprises at least 1 second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N) and fluorine (F), in the powder compact, in a predetermined cross section perpendicular to the flat surface, a void portion is included at a boundary portion between the flat surface of the flat magnetic metal particles and an inclusion phase in contact with the flat surface, and a ratio of a length of the void portion to a length of the flat surface is 20% or less.

According to the above configuration, a dust material having excellent magnetic characteristics and a rotating electrical machine using the same can be provided.

Drawings

Fig. 1 is a conceptual diagram showing an example of a method for determining the thickness of flat magnetic metal particles according to embodiment 1.

Fig. 2 is a conceptual diagram for explaining a method of determining the maximum length and the minimum length in the flat surface of the flat magnetic metal particle according to embodiment 1.

Fig. 3 is a conceptual diagram for explaining another example of the maximum length and minimum length within the flat surface in the flat magnetic metal particle according to embodiment 1.

Fig. 4 is a schematic view showing the direction of the flat magnetic metal particles according to embodiment 1 when the coercive force is measured by changing the direction at 22.5 degrees intervals with respect to an angle of 360 degrees in the flat surface.

Fig. 5 is a schematic perspective view of the flat magnetic metal particle of embodiment 1.

Fig. 6 is a schematic view of the flat magnetic metal particles of embodiment 1 as viewed from above.

Fig. 7 is a schematic view of the flat magnetic metal particle of embodiment 2.

Fig. 8 is a schematic view of the dust material of embodiment 3.

Fig. 9 is a schematic diagram showing an example of arrangement of flat magnetic metal particles on a plane parallel to each cross section in embodiment 3.

Fig. 10 is a schematic view showing an angle formed between a plane parallel to the flat surface of the flat magnetic metal particles and a plane of the powder compact in embodiment 3.

Fig. 11 is a schematic view showing a method for producing a powder compact according to embodiment 3.

Fig. 12 is a graph schematically showing an example of the temperature and pressure at the time of production in embodiment 3.

Fig. 13 is a microscope (SEM) photograph of a predetermined cross section of the powder compact according to embodiment 3.

Fig. 14 is a schematic view showing a method for producing a powder compact according to another embodiment of embodiment 3.

Fig. 15 is a schematic view showing the lengths of the flat surface and the void part in a predetermined cross section of the powder compact according to embodiment 3.

Fig. 16 is a conceptual diagram of the motor system of embodiment 4.

Fig. 17 is a conceptual diagram of the motor according to embodiment 4.

Fig. 18 is a conceptual diagram of a motor core (stator) according to embodiment 4.

Fig. 19 is a conceptual diagram of a motor core (rotor) according to embodiment 4.

Fig. 20 is a conceptual diagram of the transformer/converter of embodiment 4.

Fig. 21 is a conceptual diagram of an inductor (ring inductor, rod inductor) according to embodiment 4.

Fig. 22 is a conceptual diagram of an inductor (chip inductor, planar inductor) according to embodiment 4.

Fig. 23 is a conceptual diagram of the generator of embodiment 4.

Fig. 24 is a conceptual diagram showing a relationship between the direction of the magnetic flux and the arrangement direction of the powder compact.

Description of the symbols

2a concave part

2b convex part

4 magnetic metal small particles

6 Flat surface

8 attaching metal

9 coating layer

10 Flat magnetic metal particles

20 inclusion phase

22 defined cross section

100 pressed powder material

102 plane

200 motor

300 motor core

400 transformer/converter

500 inductor

Detailed Description

Hereinafter, embodiments will be described with reference to the drawings. In the drawings, the same or similar parts are denoted by the same or similar reference numerals.

(embodiment 1)

The plurality of flat magnetic metal particles of the present embodiment are a plurality of flat magnetic metal particles as follows: the magnetic composite material has a flat surface and a magnetic metal phase containing Fe, Co and Si, wherein the amount of Co is 0.001-80 at% based on the total amount of Fe and Co, the amount of Si is 0.001-30 at% based on the whole magnetic metal phase, the average thickness of the plurality of flat magnetic metal particles is 10 nm-100 μm, the average value of the ratio of the average length to the thickness in the flat surface is 5-10000, and the magnetic coercive force difference generated by the direction in the flat surface is poor.

The plurality of flat magnetic metal particles of the present embodiment are a plurality of flat magnetic metal particles as follows: the magnetic metal particles have a flat surface and a magnetic metal phase containing at least 1 first element selected from the group consisting of Fe, Co and Ni and an additive element, wherein the additive element contains B and Hf, the total amount of the additive element is 0.002 to 80 atomic% of the entire magnetic metal phase, the average thickness of the plurality of flat magnetic metal particles is 10nm to 100 [ mu ] m, the average value of the ratio of the average length to the thickness in the flat surface is 5 to 10000, and the magnetic field strength difference generated by the direction in the flat surface is provided.

The flat magnetic metal particles are flat particles (flat particles ) having a flat shape (flat shape, flat particle).

The thickness means an average thickness among 1 flat magnetic metal particle. The method for determining the thickness is not limited as long as the average thickness of 1 flat magnetic metal particle can be determined. For example, the following method may be employed: the cross section perpendicular to the flat surface of the flat magnetic metal particle is observed with a Transmission Electron Microscope (TEM), a Scanning Electron Microscope (SEM), an optical microscope, or the like, and arbitrary 10 or more sites are selected in the direction within the flat surface in the cross section of the observed flat magnetic metal particle, and the thickness of each selected site is measured and the average value thereof is used. In addition, the following method may be adopted: in the cross section of the flat magnetic metal particle to be observed, 10 or more sites are selected at equal intervals from the end portion toward the other end portion in the direction within the flat surface (in this case, the end portion and the other end portion are preferably not selected because they are special sites), and the thickness at each selected site is measured and the average value thereof is used. Fig. 1 is a conceptual diagram showing an example of a method for determining the thickness of flat magnetic metal particles according to embodiment 1. The thickness derivation method in this case is specifically shown in fig. 1. In any case, it is preferable that the measurement is performed at as many sites as possible because average information can be obtained. In the case where the contour line of the cross section has a contour line having a sharp unevenness or a rough surface and it is difficult to obtain an average thickness in the original state, it is preferable to perform the above-described method after smoothing the contour line with an average straight line or curve as appropriate.

The average thickness is an average value of thicknesses of the plurality of flat magnetic metal particles, and is different from the above-mentioned simple "thickness". In obtaining the average thickness, it is preferable to use a value obtained by averaging 20 or more flat magnetic metal particles. It is preferable to obtain average information for as many flat magnetic metal particles as possible. In addition, when 20 or more flat magnetic metal particles cannot be observed, it is preferable to use a value obtained by performing observation of as many flat magnetic metal particles as possible and averaging them. The average thickness of the flat magnetic metal particles is preferably 10nm to 100 μm. More preferably 10nm to 1 μm, and still more preferably 10nm to 100 nm. The flat magnetic metal particles preferably include particles having a thickness of 10nm to 100 μm, more preferably 10nm to 1 μm, and still more preferably 10nm to 100 nm. This is preferable because eddy current loss can be sufficiently reduced when a magnetic field is applied in a direction parallel to the flat surface. When the thickness is small, the magnetic moment is enclosed in a direction parallel to the flat surface, and magnetization by spin magnetization is easy, which is preferable. In the case of magnetization by spin magnetization, magnetization is easily reversible, so that the coercive force is reduced, and hysteresis loss can be reduced, which is preferable.

The average length of the flat magnetic metal particles is defined as (a + b)/2 using the maximum length a and the minimum length b in the flat plane. The maximum length a and the minimum length b can be obtained as follows. For example, a rectangle having the smallest area among rectangles circumscribing the flat surface is considered. The length of the long side of the rectangle is set to a maximum length a, and the length of the short side is set to a minimum length b. Fig. 2 is a conceptual diagram for explaining a method of determining the maximum length and the minimum length in the flat surface of the flat magnetic metal particle according to embodiment 1. Fig. 2 is a schematic diagram showing the maximum length a and the minimum length b obtained by the above method using several flat magnetic metal particles as an example. The maximum length a and the minimum length b can be determined by observing the flat magnetic metal particles with a TEM, an SEM, an optical microscope, or the like, in the same manner as the average thickness. Alternatively, the maximum length a and the minimum length b may be determined by performing image analysis of the photomicrograph on a computer. In any case, it is preferable to obtain the magnetic particles for 20 or more flat magnetic metal particles. It is preferable to obtain the information that can be averaged with respect to as many flat magnetic metal particles as possible. In addition, when 20 or more flat magnetic metal particles cannot be observed, it is preferable to use a value obtained by performing observation of as many flat magnetic metal particles as possible and averaging them. In addition, since it is preferably determined as an average value as much as possible, it is preferable to perform observation or image analysis in a state where the flat magnetic metal particles are uniformly dispersed (in a state where a plurality of flat magnetic metal particles having different maximum lengths and minimum lengths are dispersed as randomly as possible). For example, it is preferable to perform observation or image analysis by applying the magnetic tape in a state where a plurality of flat magnetic metal particles are sufficiently mixed, or by applying the magnetic tape in a state where a plurality of flat magnetic metal particles fall from above and fall to the bottom.

However, when the maximum length a and the minimum length b are obtained from the flat magnetic metal particles by the above-described method, the method may not be an essential solution. Fig. 3 is a conceptual diagram for explaining a determination method in another example of determining the maximum length and the minimum length in the flat surface in the flat magnetic metal particle according to embodiment 1. For example, in the case shown in fig. 3, the flat magnetic metal particles are elongated and bent, but in this case, the maximum length and the minimum length of the flat magnetic metal particles are substantially the lengths of a and b shown in fig. 2. As described above, the maximum lengths a and b are not completely determined in a general manner, but basically there is no problem in the method of "considering a rectangle having the smallest area among rectangles circumscribing a flat surface, and setting the length of the long side of the rectangle to be the maximum length a and the length of the short side to be the minimum length b", but if the essence cannot be grasped by this method depending on the shape of the particle, the method is obtained as the maximum length a and the minimum length b grasping the essence in an opportunistic manner. The thickness t is defined by the length in the direction perpendicular to the flat surface. The ratio a of the average length to the thickness in the flat surface is defined by a maximum length a, a minimum length b, and a thickness t as ═ ((a + b)/2)/t.

The average value of the ratio of the average length to the thickness in the flat surface of the flat magnetic metal particles is preferably 5 to 10000. This is because the magnetic permeability is thereby increased. In addition, since the ferromagnetic resonance frequency can be increased, the ferromagnetic resonance loss can be reduced.

The average length to thickness ratio in the flat plane was taken as the average value. It is preferable to use a value obtained by averaging 20 or more flat magnetic metal particles. It is preferable to obtain average information for as many flat magnetic metal particles as possible. In addition, when 20 or more flat magnetic metal particles cannot be observed, it is preferable to use a value obtained by performing observation of as many flat magnetic metal particles as possible and averaging them. For example, the particle Pa, the particle Pb, and the particle Pc are present, and when the thicknesses Ta, Tb, and Tc, and the average lengths La, Lb, and Lc in the flat surface are given, the average thickness is calculated as (Ta + Tb + Tc)/3, and the average value of the ratio of the average length to the thickness in the flat surface is calculated as (La/Ta + Lb/Tb + Lc/Tc)/3.

The flat magnetic metal particles preferably have a difference in coercive force due to orientation in the flat surface. The larger the ratio of difference in coercive force due to the direction is, the more preferable it is, 1% or more. The ratio of the difference in coercive force is more preferably 10% or more, still more preferably 50% or more, and still more preferably 100% or more. The ratio of the difference in coercive force here is defined as (hc (max) -hc (min))/hc (min) × 100 (%) using the maximum coercive force hc (max) and the minimum coercive force hc (min) in the flat surface. The coercive force can be evaluated using a Vibration Sample Magnetometer (VSM) or the like. When the coercive force is low, the coercive force of 0.1Oe or less can be measured by using a low-magnetic-field unit. The measurement was performed by changing the direction in the flat plane with respect to the direction of the measurement magnetic field.

The phrase "having a difference in coercive force" means that when a magnetic field is applied in a 360-degree direction in a flat surface and the coercive force is measured, there are a direction in which the coercive force is the largest and a direction in which the coercive force is the smallest. For example, when the coercive force is measured at 22.5 degrees of change in direction from an angle of 360 degrees in a flat surface, the "difference in coercive force" is set when a difference in coercive force is expressed, that is, when an angle at which the coercive force becomes large and an angle at which the coercive force becomes small are expressed. Fig. 4 is a schematic view showing directions in measuring the coercive force of the flat magnetic metal particles of embodiment 1 by changing the directions at 22.5 degrees intervals with respect to an angle of 360 degrees in a flat surface. By having a difference in coercive force in a flat surface, the value of the smallest coercive force becomes smaller than that in the case of isotropy having substantially no difference in coercive force, which is preferable. A material having magnetic anisotropy in a flat plane has a difference in coercivity depending on the direction in the flat plane, and the minimum value of coercivity is smaller than that of a material having magnetic anisotropy. This is preferable because the hysteresis loss is reduced and the magnetic permeability is improved.

The coercivity is related to the crystal magnetic anisotropy, and may be described by an approximate expression of Hc ═ α Ha-NMs (Hc: coercivity, Ha: crystal magnetic anisotropy, Ms: saturation magnetization, α, N: values that vary depending on composition, structure, shape, and the like). That is, generally, the coercivity tends to increase as the magnetocrystalline anisotropy increases, and tends to decrease as the magnetocrystalline anisotropy decreases. However, the α value and the N value of the approximate expression greatly change depending on the composition, the structure, and the shape of the material, and the coercive force becomes a relatively small value (when the α value is small or the N value is large) even if the magnetocrystalline anisotropy is large, or becomes a relatively large value even if the magnetocrystalline anisotropy is small (when the α value is large or the N value is small). That is, the magnetocrystalline anisotropy is a characteristic inherent to a substance depending on the composition of a material, and the coercive force is a characteristic that can be largely changed depending on not only the composition of the material but also the structure, shape, and the like. Further, the magnetocrystalline anisotropy is not a factor directly influencing the hysteresis loss but a factor indirectly influencing the hysteresis loss, but the coercive force is a factor directly influencing the loop area of the dc magnetization curve (the area corresponds to the magnitude of the hysteresis loss), and therefore the magnitude of the hysteresis loss is almost directly determined. That is, the coercive force is different from the magnetocrystalline anisotropy, and is a very important factor that directly exerts a large influence on the hysteresis loss.

In addition, since the flat magnetic metal particles have magnetic anisotropy including magnetocrystalline anisotropy, it is not always necessary to exhibit a difference in coercive force depending on the direction of the flat surface of the flat magnetic metal particles. As described above, the coercive force does not depend on the value of the magnetocrystalline anisotropy at all, but changes depending on the composition, structure, and shape of the material. As described above, the factor that directly exerts a large influence on the hysteresis loss is not the magnetic anisotropy but the coercive force. From the above, a very preferable condition for high characteristics is "having a difference in coercive force depending on the direction in the flat plane". This is preferable because hysteresis loss is reduced and magnetic permeability is increased.

The ratio a/b of the maximum length a to the minimum length b in the flat surface is preferably 2 or more, more preferably 3 or more, further preferably 5 or more, and further preferably 10 or more on average. The particles preferably include particles in which the ratio a/b of the maximum length a to the minimum length b in the flat surface is 2 or more, more preferably 3 or more, even more preferably 5 or more, and even more preferably 10 or more. This is preferable because the magnetic anisotropy can be easily imparted. When magnetic anisotropy is imparted, a difference in coercivity occurs in a flat plane, and the minimum coercivity value becomes smaller than that of a magnetically isotropic material. This is preferable because the hysteresis loss is reduced and the magnetic permeability is improved. In the flat magnetic metal particles, it is preferable that a first direction of one or both of a plurality of concave portions and a plurality of convex portions, which will be described later, is aligned along a maximum length direction. In addition, when the flat magnetic metal particles are pulverized, since the a/b of the flat magnetic metal particles is large, the area (or area ratio) where the flat surfaces of the respective flat magnetic metal particles overlap each other becomes large, and the strength as a powder compact becomes high, which is preferable. In addition, when the ratio of the maximum length to the minimum length is large, the magnetic moment is enclosed in a direction parallel to the flat surface, and magnetization by spin magnetization is easy, which is preferable. In the case of magnetization by spin magnetization, magnetization is easily reversible, so that the coercive force is reduced, and hysteresis loss can be reduced, which is preferable. On the other hand, from the viewpoint of increasing the strength, the ratio a/b of the maximum length a to the minimum length b in the flat surface is preferably 1 or more and less than 2 on average, and more preferably 1 or more and less than 1.5. This is preferable because the fluidity and filling property of the particles are improved. Further, the strength in the direction perpendicular to the flat surface is higher than that in the case where a/b is large, and it is preferable from the viewpoint of increasing the strength of the flat magnetic metal particles. Further, when the particles are pulverized, the particles are less likely to be crushed by buckling, and the stress on the particles is likely to be reduced. That is, since strain is reduced, coercive force and hysteresis loss are reduced, and stress is reduced, mechanical properties such as thermal stability, strength, and toughness are easily improved.

In addition, it is preferable to use particles having corners in at least a part of the outline shape of the flat surface. For example, a square or rectangular outline shape is preferable, and in other words, the angle of the corner is substantially 90 degrees. These are preferable because the symmetry of the atomic arrangement is reduced at the corners and the electron orbitals are constrained, so that magnetic anisotropy is easily imparted in the flat surface.

On the other hand, from the viewpoint of reducing the loss and increasing the strength, the outline shape of the flat surface is preferably formed by a rounded curve. As an extreme example, particles having a smooth contour such as a circle or an ellipse are preferable. These are preferable because the abrasion resistance of the particles is improved. Further, it is preferable that the stress is not easily concentrated around the contour shape, the magnetic strain of the flat magnetic metal particles is reduced, the coercive force is reduced, and the hysteresis loss is reduced. Since stress concentration is reduced, mechanical properties such as thermal stability, strength, and toughness are also easily improved, which is preferable.

The flat magnetic metal particles preferably have a magnetic metal phase containing Fe, Co and Si. This will be described in detail below. In the magnetic metal phase, the amount of Co is preferably 0.001 atom% to 80 atom%, more preferably 1 atom% to 60 atom%, still more preferably 5 atom% to 40 atom%, and still more preferably 10 atom% to 20 atom% with respect to the total amount of Fe and Co. This is preferable because the magnetic anisotropy is appropriately large and easily imparted, and the magnetic properties described above are improved. In addition, the Fe-Co system is preferable because it is easy to realize high saturation magnetization. Further, the composition ranges of Fe and Co are preferably within the above ranges because higher saturation magnetization can be achieved. The amount of Si is preferably 0.001 atom% to 30 atom%, more preferably 1 atom% to 25 atom%, and still more preferably 5 atom% to 20 atom% of the entire magnetic metal phase. This is preferable because the crystal magnetic anisotropy has an appropriate magnitude, the coercive force is easily reduced, and low hysteresis loss and high magnetic permeability are easily achieved.

In the case where the magnetic metal phase is a system containing Fe, Co, and Si, and the amount of Co and the amount of Si are within the above ranges, the anisotropy-imparting effect described above is particularly exhibited to a great extent. In the three atomic systems of Fe, Co and Si, in particular, magnetic anisotropy is appropriately large and easily imparted, and coercive force is reduced, as compared with a single atomic system of only Fe or Co, or a diatomic system of only Fe and Si, or only Fe and Co, and thus hysteresis loss is reduced and magnetic permeability is improved, which is preferable. This great effect is brought about in particular only when the composition range mentioned above is entered. Further, when the composition of the ternary system of Fe, Co and Si falls within the above-mentioned composition range, thermal stability and oxidation resistance are also remarkably improved, which is preferable. Further, since thermal stability and oxidation resistance are improved, mechanical properties at high temperatures are also improved, which is preferable. Further, mechanical properties at room temperature are also improved, such as strength, hardness, and wear resistance, and thus, are preferable. In the case where a ribbon is synthesized by a roll quenching method or the like and the ribbon is crushed to obtain flat magnetic metal particles in synthesizing the flat magnetic metal particles, the flat magnetic metal particles are preferably obtained in a state where the magnetic metal phase is a three-atomic system containing Fe, Co, and Si, and the amount of Co and the amount of Si are within the above ranges, because the flat magnetic metal particles are particularly easily crushed and strain is relatively less likely to enter the flat magnetic metal particles. When the strain is hard to enter the flat magnetic metal particles, the coercive force is easily reduced, and low hysteresis loss and high magnetic permeability are easily achieved, which is preferable. Further, a small strain is preferable because the stability with time is high, the thermal stability is high, and the mechanical properties such as strength, hardness, and abrasion resistance are excellent.

The average crystal grain size of the magnetic metal phase is preferably 1 μm or more, more preferably 10 μm or more, still more preferably 50 μm or more, and still more preferably 100 μm or more. When the average crystal grain size of the magnetic metal phase is large, the ratio of the surface of the magnetic metal phase is small, and therefore the pinning sites are reduced, whereby the coercive force is reduced and the hysteresis loss is reduced, which is preferable. Further, it is preferable that the average crystal grain size of the magnetic metal phase is increased within the above range because the magnetic anisotropy is appropriately large and is easily imparted, and the above magnetic properties are improved.

In particular, when the magnetic metal phase is a system containing Fe, Co, and Si, and the amount of Co and the amount of Si fall within the above ranges, respectively, and the average crystal grain size of the magnetic metal phase falls within the above ranges, the magnetic anisotropy is appropriately large and easily imparted, and the magnetic properties are significantly improved, which is more preferable. Among these, in particular, when the magnetic metal phase is a system containing Fe, Co, and Si, the amount of Co is 5 atomic% to 40 atomic%, more preferably 10 atomic% to 20 atomic%, based on the total amount of Fe and Co, and the amount of Si is 1 atomic% to 25 atomic%, more preferably 5 atomic% to 20 atomic%, based on the entire magnetic metal phase, and the average crystal grain size of the magnetic metal phase is 10 μm or more, more preferably 50 μm or more, and even more preferably 100 μm or more, the magnetic anisotropy is suitably large and easily imparted, and the magnetic properties are particularly remarkably improved, more preferably.

In addition, the magnetic metal phase preferably includes a portion having a crystal structure of a body-centered cubic structure (bcc). This is preferable because the magnetic anisotropy is appropriately large and easily imparted, and the magnetic properties described above are improved. Further, even in the "mixed-phase crystal structure of bcc and fcc" partially having a crystal structure of face-centered cubic structure (fcc), the magnetic anisotropy is suitably large and easily imparted, and the above-mentioned magnetic properties are improved, which is preferable.

The flat surfaces of the flat magnetic metal particles are preferably roughly crystallographically oriented. The orientation direction is preferably (110) plane orientation. This is preferable because the magnetic anisotropy is appropriately large and easily imparted, and the magnetic properties described above are improved. A more preferable orientation direction is the (110) [111] direction. This is preferable because the magnetic anisotropy is appropriately large and easily imparted, and the magnetic properties described above are improved. The flat magnetic metal particles preferably have a peak intensity ratio of the flat crystal surface (e.g., crystal surfaces (200), (211), (310), and (222)) other than the flat crystal surface (110) and (220) as measured by XRD (X-ray diffraction) with respect to (110), which is 10% or less, more preferably 5% or less, and still more preferably 3% or less. This is preferable because the magnetic anisotropy is appropriately large and easily imparted, and the magnetic properties described above are improved.

In order to orient (110) the flat surfaces of the flat magnetic metal particles, it is effective to select appropriate heat treatment conditions. The heat treatment temperature is preferably set to 800 to 1200 ℃, more preferably 850 to 1100 ℃, still more preferably 900 to 1000 ℃, and yet more preferably 920 to 980 ℃ (preferably around 940 ℃). The (110) orientation is difficult regardless of whether the heat treatment temperature is too low or too high, and the heat treatment temperature in the above range is most preferable. The heat treatment time is preferably 10 minutes or more, more preferably 1 hour or more, and further preferablyPreferably about 4 hours. The (110) orientation is difficult to perform regardless of whether the heat treatment time is too short or too long, and a heat treatment time of about 4 hours is most preferable. The heat treatment atmosphere is preferably a vacuum atmosphere having a low oxygen concentration, an inert atmosphere, or a reducing atmosphere, and more preferably H₂(Hydrogen), CO (carbon monoxide), CH₄(methane) and the like. This is preferable because oxidation of the flat magnetic metal particles is suppressed and the oxidized portion can be reduced. By selecting the heat treatment conditions or more, the orientation of (110) becomes easy, and the crystal planes other than (110) and (220) (for example, (200), (211), (310), and (222) can be made 10% or less, further 5% or less, and further 3% or less, for the first time, in terms of the peak intensity ratio measured by XRD (X-ray diffraction method) with respect to (110). Further, strain can be removed appropriately, and a state in which oxidation is suppressed (a reduced state) can be realized, which is preferable.

The flat magnetic metal particles preferably have a magnetic metal phase containing at least 1 first element selected from the group consisting of Fe, Co, and Ni, and an additive element. This will be described in detail below. The above-mentioned additive element more preferably contains B, Hf. The total amount of the additive elements is preferably 0.002 atom% to 80 atom%, more preferably 5 atom% to 80 atom%, still more preferably 5 atom% to 40 atom%, and still more preferably 10 atom% to 40 atom%, based on the entire magnetic metal phase. This is preferable because the amorphous state is advanced, magnetic anisotropy is easily imparted, and the magnetic properties described above are improved. The amount of Hf is preferably 0.001 atom% to 40 atom%, more preferably 1 atom% to 30 atom%, even more preferably 1 atom% to 20 atom%, even more preferably 1 atom% to 15 atom%, even more preferably 1 atom% to 10 atom%, based on the entire magnetic metal phase. This is preferable because the amorphous state is advanced, magnetic anisotropy is easily imparted, and the magnetic properties described above are improved.

In the case where the magnetic metal phase is a system including the first element and B, Hf as the additive element, and the total amount of the additive elements and the amount of Hf fall within the above ranges, a large effect is exhibited particularly with respect to the anisotropy-imparting effect. This great effect is brought about in particular only when the composition range mentioned above is entered. In addition, in particular, in the system containing Hf, compared with the system containing other additive elements, amorphization is easily progressed by a small amount, magnetic anisotropy is easily given, and compatibility with high saturation magnetization is easily achieved, which is preferable. Hf has a high melting point and is preferably contained in the above-described amount range in the magnetic metal phase, so that thermal stability and oxidation resistance are particularly improved. Further, since thermal stability and oxidation resistance are improved, mechanical properties at high temperatures are also improved, which is preferable. Further, mechanical properties at room temperature are also improved, such as strength, hardness, and wear resistance, and thus, are preferable. In the case where a ribbon is synthesized by a roll quenching method or the like and the ribbon is crushed to obtain flat magnetic metal particles in synthesizing the flat magnetic metal particles, it is preferable that the magnetic metal phase is a system containing the first element and B, Hf as the additive element, and the total amount of the additive element and the amount of Hf are in the above ranges, because the magnetic metal phase is particularly easily crushed, and thus a state in which strain is less likely to enter the flat magnetic metal particles can be realized. When the strain is hard to enter the flat magnetic metal particles, the coercive force is easily reduced, and low hysteresis loss and high magnetic permeability are easily achieved, which is preferable. Further, a small strain is preferable because the stability with time is high, the thermal stability is high, and the mechanical properties such as strength, hardness, and abrasion resistance are excellent.

Further, when the magnetic metal phase is a system including the first element and B, Hf as the additive element, and the total amount of the additive elements and the amount of Hf fall within the above ranges, the thermal stability is excellent, and therefore, the optimal heat treatment conditions for the flat magnetic metal particles can be set relatively high. That is, in the method for producing flat magnetic metal particles, the ribbon is synthesized, the obtained ribbon is crushed by applying heat treatment (or not), and then, heat treatment is preferably performed to remove strain (more preferably, heat treatment in a magnetic field), and the heat treatment temperature at this time can be set relatively high. This makes it easy to relieve strain and to realize a low-loss material with less strain. For example, by performing a heat treatment at 500 ℃ or higher, a low-loss material can be easily realized (a low-loss material can be realized at a heat treatment temperature higher than that of other systems or compositions, and a heat treatment temperature of about 400 ℃ is an optimum heat treatment temperature for other systems or compositions, for example).

The additive element preferably contains, in addition to B, Hf, at least one other "different element". The "different element" is preferably C, Ta, W, P, N, Mg, Al, Si, Ca, Zr, Ti, Zn, Mn, Ba, Sr, Cr, Mo, Ag, Ga, Sc, V, Nb, Pb, Cu, In, Sn, or a rare earth element, more preferably a rare earth element, and still more preferably Y. By containing "another different element", diffusion of the element contained in the magnetic metal phase is effectively suppressed, amorphization progresses, and magnetic anisotropy is easily imparted, and is more preferable (low coercive force, low hysteresis loss, and high magnetic permeability are easily achieved, and is thus preferable). In particular, by "another different element" having an atomic radius different from B, Hf, diffusion of the element contained in the magnetic metal phase is effectively suppressed. For example, Y and the like have an atomic radius larger than B, Hf, and therefore diffusion of elements contained in the magnetic metal phase can be suppressed very effectively. Hereinafter, a preferable composition range will be described by taking a case where "another different element" is Y as an example. The amount of Y is preferably 1 atom% to 80 atom%, more preferably 2 atom% to 60 atom%, and still more preferably 4 atom% to 60 atom% based on the total amount of Hf and Y. The total amount of Hf and Y is preferably 0.002 to 40 atomic%, more preferably 1 to 30 atomic%, still more preferably 1 to 20 atomic%, still more preferably 1 to 15 atomic%, and yet more preferably 1 to 10 atomic% of the entire magnetic metal phase. This is preferable because the amorphous state is advanced, magnetic anisotropy is easily imparted, and the magnetic properties described above are improved. By falling within the above composition range, the above anisotropy-imparting effect is more significantly exhibited than the case where the additive element is only B, Hf. This significantly large effect is brought about in particular only when the above-mentioned composition range is entered. Further, it is preferable that the amount of the magnetic material is small, so that amorphization is easily advanced, magnetic anisotropy is easily imparted, and compatibility with high saturation magnetization is easily achieved. In the system containing Y, the composition is appropriately selected, whereby the characteristics which cannot be achieved by the system of BHf can be achieved for the first time. Further, thermal stability and oxidation resistance are particularly improved, and therefore, such is preferable. Further, since thermal stability and oxidation resistance are improved, mechanical properties at high temperatures are also improved, which is preferable. Further, mechanical properties at room temperature are also improved, such as strength, hardness, and wear resistance, and thus, are preferable.

The average crystal grain size of the magnetic metal phase is preferably 100nm or less, more preferably 50nm or less, still more preferably 20nm or less, and still more preferably 10nm or less. The smaller the diameter is, the more preferable is 5nm or less, and the more preferable is 2nm or less. This makes it easy to impart anisotropy, and the magnetic properties described above are improved, which is preferable. Further, since a small crystal particle size means a nearly amorphous form, it is preferable that the resistance is higher than that of a highly crystalline particle, and thus the eddy current loss is easily reduced. Further, it is preferable to be more excellent in corrosion resistance and oxidation resistance than the highly crystalline particles.

In the case where the additive element includes, in addition to B, Hf, at least one other "different element (e.g., Y)", the amount of the "different element (e.g., Y)", and the total amount of Hf and the "different element (e.g., Y)" fall within the above-described range, it is preferable because an average crystal grain size of 30nm or less can be relatively easily achieved. That is, the particles are more amorphous, so that the resistance is higher than that of the particles having high crystallinity, and thus the eddy current loss is easily reduced, which is preferable. Further, it is preferable to be more excellent in corrosion resistance and oxidation resistance than the highly crystalline particles. Further, anisotropy is easily imparted, and the above-described magnetic properties are improved, which is preferable.

In particular, when the magnetic metal phase is a system including the first element and B, Hf as the additive element, and the total amount of the additive elements and the amount of Hf are within the above ranges, respectively, and the average crystal grain size of the magnetic metal phase is within the above ranges, the magnetic properties are improved by the effect of imparting magnetic anisotropy, and the effects of high resistance (reduction in eddy current loss), high corrosion resistance, and high oxidation resistance by amorphization are significantly improved, and more preferably. Particularly, when the magnetic metal phase is a system containing the first element and B, Hf as the additive element, the total amount of the additive elements is 5 atom% to 40 atom%, more preferably 10 atom% to 40 atom%, and the amount of Hf is 1 atom% to 20 atom%, more preferably 1 atom% to 15 atom%, and even more preferably 1 atom% to 10 atom% with respect to the entire magnetic metal phase, and the average crystal grain size of the magnetic metal phase is 50nm or less, more preferably 20nm or less, and even more preferably 10nm or less, the effects of improvement in magnetic characteristics by the effect of imparting magnetic anisotropy, high resistance by amorphous formation (reduction in eddy current loss), high corrosion resistance, and high oxidation resistance are particularly remarkably improved, more preferably.

The crystal particle size of 100nm or less can be easily calculated by the Scherrer formula measured by XRD, or can be obtained by observing many magnetic metal phases by TEM (Transmission electron microscope) observation and averaging the particle sizes. When the crystal grain size is small, it is preferably determined by XRD measurement, and when the crystal grain size is large, it is preferably determined by TEM observation, and it is preferable to select a measurement method in some cases or to use both methods together for comprehensive judgment.

The flat magnetic metal particles preferably have a high saturation magnetization, and are preferably 1T or more, more preferably 1.5T or more, still more preferably 1.8T or more, and still more preferably 2.0T or more. This suppresses magnetic saturation, and is preferable because the magnetic properties can be sufficiently exhibited in the system. However, depending on the application (for example, a magnetic wedge of a motor), the magnetic flux density can be sufficiently used even when the saturation magnetization is relatively small, and it is preferable to specify the magnetic flux density to be low loss in some cases. The magnetic wedge of the motor is a wedge like a cover with a slot portion of a coil, and a nonmagnetic wedge is generally used, but by using a magnetic wedge, density of magnetic flux density is reduced, high-frequency loss is reduced, and motor efficiency is improved. In this case, the saturation magnetization of the magnetic wedge is preferably large, and a sufficient effect is exhibited even with a relatively small saturation magnetization. Thus, it is important to select the composition according to the use.

The lattice strain of the flat magnetic metal particles is preferably 0.01% to 10%, more preferably 0.01% to 5%, even more preferably 0.01% to 1%, and even more preferably 0.01% to 0.5%. This is preferable because the magnetic anisotropy is appropriately large and easily imparted, and the magnetic properties described above are improved.

The lattice strain can be calculated by analyzing the line width obtained by X-Ray Diffraction (XRD: X-Ray Diffraction) in detail. That is, by performing the Halder-Wagner plot, the Hall-Williamson plot, useful components of the expansion of the line width can be separated into the crystal grain diameter and the lattice strain. From this, the lattice strain can be calculated. The Halder-Wagner rendering is preferred from a reliability point of view. For the Halder-Wagner rendering, for example, reference is made to n.c. Halder, c.n.j.wagner, Acta cryst.20(1966) 312-. Wherein the Halder-Wagner plot is represented by the following equation.

(beta. integral width, K: constant, lambda: wavelength, D: crystal particle diameter,Lattice strain (square mean square root)

I.e. the longitudinal axis takes beta²/tan²The horizontal axis of θ is plotted as β/tan θ sin θ, and the crystal grain size D is calculated from the slope of the approximate line, and the lattice strain ∈ is calculated from the vertical axis slice. When the lattice strain (square average square root)) obtained by the Halder-Wagner plotting of the above formula is 0.01% to 10%, more preferably 0.01% to 5%, still more preferably 0.01% to 1%, and still more preferably 0.01% to 0.5%, the magnetic anisotropy is suitably large and easily imparted, and the above magnetic properties are improved, which is preferable.

The above-described lattice strain analysis is an effective method when a plurality of peaks in XRD can be detected, but is difficult when the peak intensity in XRD is weak and the number of detectable peaks is small (for example, only 1 peak can be detected). In such a case, the lattice strain is preferably calculated by the following procedure. First, the composition was determined by high-frequency Inductively Coupled Plasma (ICP: Inductively Coupled Plasma) luminescence analysis, Energy Dispersive X-ray Spectroscopy (EDX: Energy Dispersive X-ray Spectroscopy), and the like, and 3 composition ratios of the magnetic metal elements Fe, Co, and Ni (two composition ratios in the case of only two magnetic metal elements, and 1 composition ratio (═ 100%) in the case of only 1 magnetic metal element) were calculated. Next, the ideal interplanar spacing d is calculated from the composition of Fe-Co-Ni₀(see literature values, etc. in some cases, an alloy of this composition was prepared and measured to calculate the interplanar spacing). Then, the interplanar spacing d of the peak of the measurement sample and the ideal interplanar spacing d are determined₀The difference can be used to determine the amount of strain. That is, in this case, the strain amount is (d-d)₀)/d₀X 100 (%). In summary, the two methods described above are used separately for analysis of the lattice strain depending on the state of the peak intensity, and in some cases, it is preferable to use both methods for evaluation.

The interplanar spacings in the plane vary according to direction, with the maximum interplanar spacing d being preferred_maxDistance d from minimum interplanar_minRatio of difference (═ d)_max-d_min)/d_minX 100 (%)) is preferably 0.01 to 10%, more preferably 0.01 to 5%, and still more preferably 0.01 to 1%, and more preferably 0.01 to 0.5%. This is preferable because the magnetic anisotropy is appropriately large and easily imparted, and the magnetic properties described above are improved. The interplanar spacing can be easily determined by XRD measurement. By performing this XRD measurement while changing the direction in the plane, the difference in lattice constant due to the direction can be obtained.

The crystallites of the flat magnetic metal particles are preferably connected to each other in one direction in a flat plane, or are rod-shaped and oriented in one direction in a flat plane. This is preferable because the magnetic anisotropy is appropriately large and easily imparted, and the magnetic properties described above are improved.

The flat surface of the flat magnetic metal particles preferably has one or both of a plurality of concave portions and a plurality of convex portions arranged in the first direction, each having a width of 0.1 μm or more, a length of 1 μm or more, and an aspect ratio of 2 or more. This is preferable because magnetic anisotropy is easily induced in the first direction, and the difference in coercive force due to the direction becomes large in a flat surface. From this viewpoint, the width is more preferably 1 μm or more, and the length is preferably 10 μm or more. The aspect ratio is preferably 5 or more, and more preferably 10 or more. Further, the provision of such a concave portion or a convex portion is preferable because the adhesion between the flat magnetic metal particles when the flat magnetic metal particles are pulverized to synthesize a powder compact material is improved (the concave portion or the convex portion brings an effect of an anchor ring for bonding the particles to each other), and thus mechanical properties such as strength and hardness and thermal stability are improved.

Fig. 5 is a schematic perspective view of the flat magnetic metal particle of embodiment 1. In addition, only the concave portion is provided in the upper diagram of fig. 5, and only the convex portion is provided in the central diagram of fig. 5, but one flat magnetic metal particle may have both the concave portion and the convex portion as in the lower diagram of fig. 5. Fig. 6 is a schematic view of the flat magnetic metal particles of embodiment 1 as viewed from above. The width and length of the concave or convex portions and the distance between the concave or convex portions are shown. One flat magnetic metal particle may also have both a concave portion and a convex portion. The aspect ratio of the concave portion or the convex portion is a length of a major axis/a length of a minor axis. That is, in the case where the length of the concave or convex portion is larger (longer) than the width, the aspect ratio is defined by the length/width, and in the case where the width is larger (longer) than the length, the aspect ratio is defined by the width/length. When the length/width ratio is large, magnetic uniaxial anisotropy (anisotropy) tends to be easily obtained, and is more preferable. Fig. 6 shows a concave portion 2a, a convex portion 2b, a flat surface 6, and flat magnetic metal particles 10.

The term "aligned in the first direction" means that the longer one of the length and the width of the concave or convex portions is aligned parallel to the first direction. In addition, if the longer one of the length and the width of the concave or convex portion is aligned within ± 30 degrees in the direction parallel to the first direction, it is set as "aligned in the first direction". By these, the flat magnetic metal particles are preferable because the flat magnetic metal particles easily have magnetic uniaxial anisotropy in the first direction due to the effect of the shape magnetic anisotropy. The flat magnetic metal particles preferably have magnetic anisotropy in one direction in a flat plane, and the details thereof will be described. First, when the magnetic domain structure of the flat magnetic metal particles is a multi-domain structure, the magnetization process proceeds by the movement of the magnetic domain wall, and in this case, the easy axis direction in the flat surface becomes smaller than the difficult axis direction, and the loss (hysteresis loss) becomes smaller. In addition, the magnetic permeability in the easy axis direction is higher than that in the difficult axis direction. In addition, the case of the flat magnetic metal particles having magnetic anisotropy is preferable because the coercive force becomes smaller particularly in the axial direction and the loss becomes smaller as compared with the case of the isotropic flat magnetic metal particles. Further, the magnetic permeability is also increased, which is preferable. That is, by having magnetic anisotropy in the flat in-plane direction, the magnetic properties are improved compared with isotropic materials. In particular, the easy axis direction in the flat surface is preferable because it is superior in magnetic properties to the difficult axis direction. Next, in the case where the magnetic domain structure of the flat magnetic metal particles is a single magnetic domain structure, the magnetization process is performed by rotating magnetization, and in this case, the coercive force in the difficult axis direction in the flat surface is smaller than that in the easy axis direction, and the loss is smaller. When magnetization is performed completely by spin magnetization, the coercive force is preferably zero and the hysteresis loss is preferably zero. Whether magnetization is performed by domain wall movement (domain wall movement type) or by rotational magnetization (rotational magnetization type) depends on whether the magnetic domain structure is a multi-domain structure or a single-domain structure. In this case, whether the structure is a multi-domain structure or a single-domain structure depends on the size (thickness, aspect ratio) of the flat magnetic metal particles, the composition, the interaction between the particles, and the like. For example, the smaller the thickness t of the flat magnetic metal particles, the easier the structure becomes, and the thickness of 10nm to 1 μm, particularly 10nm to 100nm, the structure becomes easily a single magnetic domain. As a composition, in a composition having a large magnetocrystalline anisotropy, a single magnetic domain structure is easily maintained even if the thickness is large, and in a composition having a small magnetocrystalline anisotropy, it tends to be difficult to maintain a single magnetic domain structure unless the thickness is small. That is, the thickness of the boundary between the single domain structure and the multi-domain structure varies depending on the composition. In addition, when the flat magnetic metal particles are magnetically bonded to each other to stabilize the magnetic domain structure, the magnetic domain structure is easily a single magnetic domain structure. The determination of whether the magnetization behavior is a domain wall moving type or a rotating magnetization type can be easily determined as follows. First, magnetization measurement is performed by changing the direction of an applied magnetic field in the plane of the material (plane parallel to the flat surface of the flat magnetic metal particles), and two directions in which the difference in magnetization curve becomes maximum (in this case, the two directions are directions inclined by 90 degrees from each other) are found. Next, by comparing the curves in the two directions, it is possible to determine whether the domain wall moving type or the spin magnetization type is used.

As described above, the flat magnetic metal particles preferably have magnetic anisotropy in one direction in the flat surface, and more preferably, the flat magnetic metal particles have one or both of a plurality of concave portions and a plurality of convex portions arranged in the first direction, each having a width of 0.1 μm or more, a length of 1 μm or more, and an aspect ratio of 2 or more, so that the magnetic anisotropy is easily induced in the first direction, and more preferably. From this viewpoint, the width is more preferably 1 μm or more and the length is more preferably 10 μm or more. The aspect ratio is preferably 5 or more, and more preferably 10 or more. Further, the provision of such a concave portion or a convex portion is preferable because the adhesion between the flat magnetic metal particles when the flat magnetic metal particles are pulverized to synthesize a powder compact material is improved (the concave portion or the convex portion brings an effect of an anchor ring for bonding the particles to each other), and thus mechanical properties such as strength and hardness and thermal stability are improved.

In the flat magnetic metal particles, the first direction in which one or both of the plurality of concave portions and the plurality of convex portions are most arranged in the magnetization easy axis direction is preferable. That is, when there are many alignment directions (first directions) in the flat surface of the flat magnetic metal particles, it is preferable that the most numerous alignment directions (first directions) match the easy axis direction of the flat magnetic metal particles. Since the first direction, which is the longitudinal direction in which the recesses or projections are arranged, is likely to become the axis of easy magnetization due to the effect of shape magnetic anisotropy, it is preferable that the magnetic anisotropy be easily imparted when the directions are aligned to become the axes of easy magnetization.

One or both of the plurality of concave portions and the plurality of convex portions preferably include 5 or more on average in 1 flat magnetic metal particle. The number of the concave portions may be 5 or more, the number of the convex portions may be 5 or more, and the sum of the number of the concave portions and the number of the convex portions may be 5 or more. More preferably, the number of the cells is 10 or more. The average distance in the width direction between the concave portions or the convex portions is preferably 0.1 to 100 μm. More preferably, a plurality of adhesion metals each containing at least 1 of the first element selected from the group consisting of Fe, Co, and Ni and having an average size of 1nm to 1 μm are arranged along the concave portions or the convex portions. The method of determining the average size of the deposit metal is calculated by averaging the sizes of a plurality of deposit metals arranged along the concave portions or the convex portions based on observation by a TEM, an SEM, an optical microscope, or the like. When these conditions are satisfied, magnetic anisotropy is easily induced in one direction, which is preferable. Further, when the flat magnetic metal particles are pulverized to synthesize a powder compact material, the adhesion between the flat magnetic metal particles is improved (the concave portions or the convex portions bring an effect of anchor rings for bonding the particles to each other), and thus mechanical properties such as strength and hardness and thermal stability are improved, which is preferable.

The flat magnetic metal particles preferably further include a plurality of small magnetic metal particles of 5 or more on average on the flat surface. The magnetic metal particles contain at least 1 first element selected from the group consisting of Fe, Co and Ni, and have an average particle diameter of 10nm to 1 μm. More preferably, the small magnetic metal particles have a composition equivalent to that of the flat magnetic metal particles. By providing the small magnetic metal particles on the surface of the flat surface or integrating the small magnetic metal particles and the flat magnetic metal particles, the surface of the flat magnetic metal particles is in a state of being pseudo slightly rough, and thus, the adhesion when the flat magnetic metal particles are pulverized together with an impurity phase described later is greatly improved. This makes it easy to improve the mechanical properties such as thermal stability, strength, and toughness. In order to maximize such effects, it is preferable to set the average particle diameter of the small magnetic metal particles to 10nm to 1 μm and to integrate 5 or more small magnetic metal particles on average with the flat surface which is the surface of the flat magnetic metal particles. It is more preferable that the magnetic metal small particles are aligned in one direction in a flat plane because magnetic anisotropy is easily imparted to the flat plane, and high magnetic permeability and low loss are easily achieved. The average particle diameter of the magnetic metal small particles can be determined by observation with TEM, SEM, optical microscope, or the like.

The unevenness of the particle size distribution of the flat magnetic metal particles can be defined by a coefficient of variation (CV value). That is, CV value (%) ([ standard deviation of particle size distribution (μm)/average particle diameter (μm) ] × 100. It can be said that the smaller the CV value, the smaller the unevenness of the particle size distribution and the sharper the particle size distribution. When the CV value defined above is 0.1% to 60%, low coercive force, low hysteresis loss, high magnetic permeability, and high thermal stability can be achieved, and therefore, such a value is preferable. Further, since there is little variation, high yield is also easily achieved. More preferably, the CV value is in the range of 0.1% to 40%.

Imparting a directional influence on the flat surface of the flat magnetic metal particlesThe 1 effective method for the difference in coercive force of (1) is a method of performing heat treatment in a magnetic field. It is preferable that the heat treatment is performed while applying a magnetic field in one direction in the flat surface. Before the heat treatment in the magnetic field, it is preferable to find the easy axis direction in the flat plane (find the direction in which the coercive force is the smallest) and perform the heat treatment while applying the magnetic field in this direction. The larger the magnetic field applied, the more preferable is the application of 1kOe or more, and the more preferable is the application of 10kOe or more. This is preferable because the flat magnetic metal particles can exhibit magnetic anisotropy on the flat surface, and can impart a difference in coercive force due to orientation, thereby realizing excellent magnetic properties. The heat treatment is preferably carried out at a temperature of 50 to 800 ℃. The atmosphere for the heat treatment is preferably a vacuum atmosphere having a low oxygen concentration, an inert atmosphere, or a reducing atmosphere, and more preferably H₂(Hydrogen), CO (carbon monoxide), CH₄(methane) and the like. This is because even when the flat magnetic metal particles are oxidized, the oxidized metal can be reduced and recovered to the metal by performing the heat treatment in the reducing atmosphere. This can reduce the flat magnetic metal particles oxidized and reduced in saturation magnetization, thereby restoring the saturation magnetization. Since the crystallization of the flat magnetic metal particles significantly proceeds by the heat treatment, the characteristics deteriorate (the coercive force increases and the magnetic permeability decreases), and therefore, it is preferable to select the conditions so as to suppress the excessive crystallization.

In the case of synthesizing flat magnetic metal particles, when a ribbon is synthesized by a roll quenching method or the like and the ribbon is pulverized to obtain flat magnetic metal particles, it is preferable that one or both of the plurality of concave portions and the plurality of convex portions are easily aligned in the first direction (the concave portions and the convex portions are easily formed in the rotation direction of the roll) at the time of synthesizing the ribbon, and thus a difference in coercive force due to the direction is easily generated in the flat surface. That is, it is preferable that one or both of the plurality of concave portions and the plurality of convex portions in the flat surface are aligned in the first direction to be easily oriented in the magnetization easy axis direction, and that a difference in coercive force due to the orientation can be effectively given in the flat surface.

According to the present embodiment, flat magnetic metal particles having excellent magnetic characteristics such as low magnetic loss can be provided.

(embodiment 2)

The plurality of flat magnetic metal particles of the present embodiment is different from embodiment 1 in that at least a part of the surface of the flat magnetic metal particles is covered with a coating layer having a thickness of 0.1nm to 1 μm and containing at least 1 second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N), and fluorine (F).

Description of overlapping contents with embodiment 1 is omitted.

Fig. 7 is a schematic view of the flat magnetic metal particle of embodiment 2. The coating 9 is shown.

The coating layer more preferably contains at least 1 nonmagnetic metal selected from the group consisting of Mg, Al, Si, Ca, Zr, Ti, Hf, Zn, Mn, Ba, Sr, Cr, Mo, Ag, Ga, Sc, V, Y, Nb, Pb, Cu, In, Sn, and rare earth elements, and at least 1 second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N), and fluorine (F). As the nonmagnetic metal, Al and Si are particularly preferable from the viewpoint of thermal stability. When the flat magnetic metal particles contain at least 1 nonmagnetic metal selected from the group consisting of Mg, Al, Si, Ca, Zr, Ti, Hf, Zn, Mn, Ba, Sr, Cr, Mo, Ag, Ga, Sc, V, Y, Nb, Pb, Cu, In, Sn, and rare earth elements, the coating layer more preferably contains at least 1 nonmagnetic metal identical to the nonmagnetic metal that is one of the constituent components of the flat magnetic metal particles. Among oxygen (O), carbon (C), nitrogen (N) and fluorine (F), oxygen (O) is preferably contained, and oxides and composite oxides are preferred. This is because the coating layer is easily formed, and is resistant to oxidation and thermal stability. As a result, the adhesion between the flat magnetic metal particles and the coating layer can be improved, and the thermal stability and oxidation resistance of the green compact described later can be improved. The coating layer can improve not only the thermal stability and oxidation resistance of the flat magnetic metal particles, but also the electrical resistance of the flat magnetic metal particles. By increasing the resistance, the eddy current loss can be suppressed, and the frequency characteristic of the magnetic permeability can be improved. Therefore, the coating layer 14 is preferably electrically high-resistance, and preferably has a resistance value of 1m Ω · cm or more, for example.

The presence of the coating layer is also preferable from the viewpoint of magnetism. The flat magnetic metal particles are considered to be a pseudo thin film because the thickness is small relative to the size of the flat surface. In this case, a structure in which the coating layers are formed on the surfaces of the flat magnetic metal particles and integrated can be regarded as a pseudo laminated thin film structure, and the magnetic domain structure is stabilized in terms of energy. This is preferable because the coercive force can be reduced (and thus the hysteresis loss can be reduced). In this case, the magnetic permeability is also increased, which is preferable. From such a viewpoint, the coating layer is more preferably nonmagnetic (the magnetic domain structure is easily stabilized).

The thickness of the coating layer is preferably larger from the viewpoint of thermal stability, oxidation resistance and electric resistance. However, if the thickness of the coating layer is too large, saturation magnetization becomes small, and therefore magnetic permeability also becomes small, which is not preferable. In addition, from the viewpoint of magnetic properties, if the thickness is too large, the "effect of stabilizing the magnetic domain structure and reducing the coercivity, loss, and permeability" is reduced. In view of the above, the thickness of the coating layer is preferably 0.1nm to 1 μm, more preferably 0.1nm to 100 m.

As described above, according to the present embodiment, flat magnetic metal particles having excellent characteristics such as high magnetic permeability, low loss, excellent mechanical characteristics, and high thermal stability can be provided.

(embodiment 3)

The powder compact of the present embodiment is a powder compact including a plurality of flat magnetic metal particles and an inclusion phase, wherein the flat magnetic metal particles have a flat surface and a magnetic metal phase containing Fe, Co, and Si, the amount of Co is 0.001 atomic% to 80 atomic% with respect to the total amount of Fe and Co, the amount of Si is 0.001 atomic% to 30 atomic% with respect to the entire magnetic metal phase, the average thickness is 10nm to 100 μm, the average value of the ratio of the average length to the thickness in the flat surface is 5 to 10000, the inclusion phase is present between the flat magnetic metal particles, contains at least 1 second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N), and fluorine (F), and has a difference in coercive force due to direction in the plane of the powder compact.

The powder compact of the present embodiment is a powder compact including a plurality of flat magnetic metal particles and an inclusion phase, wherein the flat magnetic metal particles have a flat surface and a magnetic metal phase including at least 1 first element selected from the group consisting of Fe, Co, and Ni and an additive element, the additive element includes B, Hf, the total amount of the additive element is 0.002 to 80 atomic% of the entire magnetic metal phase, the average thickness is 10nm to 100 μm, the average value of the ratio of the average length to the thickness in the flat surface is 5 to 10000, the inclusion phase is present between the flat magnetic metal particles, contains at least 1 second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N), and fluorine (F), and has a difference in coercivity due to orientation in the flat surface. The powder compact of the embodiment is a powder compact including a plurality of flat magnetic metal particles and an inclusion phase, the flat magnetic metal particles have flat surfaces and a magnetic metal phase containing at least 1 first element selected from the group consisting of Fe, Co and Ni, the average thickness is 10nm to 100 [ mu ] m, the average value of the ratio of the average length to the thickness in the flat surfaces is 5 to 10000, the inclusion phase is present between the flat magnetic metal particles, and comprises at least 1 second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N) and fluorine (F), in the powder compact, in a predetermined cross section perpendicular to the flat surface, a void portion is included at a boundary portion between the flat surface of the flat magnetic metal particles and an inclusion phase in contact with the flat surface, and a ratio of a length of the void portion to a length of the flat surface is 20% or less.

The composition, average crystal grain size, and crystal orientation (approximately (110) orientation) of the magnetic metal phase preferably satisfy the requirements described in embodiment 1, and the description thereof is omitted here for redundancy. As an example of the powder compact, a powder compact obtained by compression molding the flat magnetic metal particles described in embodiment 1 or embodiment 2 can be given.

The saturation magnetization of the powder compact is preferably high, preferably 0.2T or more, more preferably 0.5T or more, more preferably 1.0T or more, still more preferably 1.8T or more, and still more preferably 2.0T or more. This suppresses magnetic saturation, and is preferable because the magnetic properties can be sufficiently exhibited in the system. However, depending on the application (for example, a magnetic wedge of a motor), the magnetic flux density can be sufficiently used even when the saturation magnetization is relatively small, and it is preferable to specify the magnetic flux density to be low loss in some cases. Thus, it is important to select the composition according to the use.

Fig. 8 is a schematic view of the dust material of embodiment 3. The inclusion phase 20, the dust material 100, the plane 102 of the dust material are shown. The diagram shown in the right side of fig. 8 is a schematic diagram in which hatching is removed from the diagram shown in the left side of fig. 8 to facilitate observation of inclusion phases.

An example of the predetermined cross sections 22a and 22b is shown on the right side of fig. 8. In the present embodiment, the flat surface 6 is oriented parallel to the plane 102 of the powder compact. The "predetermined cross section 22" is a cross section of the powder compact 100 perpendicular to the plane 102. It is to be noted that the method of obtaining the "predetermined cross section 22" is not limited to the method specified in fig. 8.

Fig. 9 is a schematic diagram showing an example of arrangement of flat magnetic metal particles on a plane parallel to each cross section in embodiment 3. The dust material 100 shown as an example in fig. 9 has a rectangular parallelepiped shape having a vertical length a, a horizontal length b, and a height c. Further, the surface 102 of the powder compact is set as the upper surface (or lower surface) of the powder compact 100 in fig. 9. In this case, since the flat magnetic metal particles 6 are oriented parallel to the surface 102(ab surface) of the dust material, the arrangement of the flat magnetic metal particles 6 is, for example, as shown in the lower drawing of fig. 9 (in the case of fig. 9, elongated flat magnetic metal particles are used in which the ratio a/b of the maximum length a to the minimum length b in the flat surface of the flat magnetic metal particles is slightly larger). The plane perpendicular to the ab plane is a "predetermined cross section". For example, a plane parallel to the bc plane or a plane parallel to the ac plane may be a "predetermined cross section" (in addition to this, a plane perpendicular to the ab plane may be arbitrarily determined, and this plane may be set as a "predetermined cross section"). The method of taking the "surface of the powder compact" and the "predetermined cross section" is not limited to this.

Is defined as: the angle between the plane parallel to the flat surface of the flat magnetic metal particles and the plane of the powder compact is oriented toward 0 degrees. Fig. 10 is a schematic view showing an angle formed between a plane parallel to the flat surface of the flat magnetic metal particles and a plane of the powder compact in embodiment 3. The above-mentioned angles are obtained for a large number of flat magnetic metal particles of 10 or more, and the average value thereof is preferably 0 to 45 degrees, more preferably 0 to 30 degrees, and still more preferably 0 to 10 degrees. That is, in the powder compact, the flat surfaces of the plurality of flat magnetic metal particles are preferably oriented in a layer so as to be parallel to each other or to be close to parallel to each other. This is preferable because the eddy current loss of the powder compact can be reduced. Further, since the back magnetic field can be reduced, the magnetic permeability of the powder compact can be increased, which is preferable. Further, since the ferromagnetic resonance frequency can be increased, the ferromagnetic resonance loss can be reduced, which is preferable. Further, such a laminated structure is preferable because the magnetic domain structure is stabilized and low magnetic loss can be achieved.

When the coercive force generated by the direction is measured in the above-mentioned plane (in a plane parallel to the flat surface of the flat magnetic metal particles) of the dust material, the coercive force is measured by changing the direction at intervals of 22.5 degrees with respect to an angle of 360 degrees in the above-mentioned plane, for example.

By having a difference in coercive force in the above-mentioned plane of the powder compact, the value of the smallest coercive force becomes smaller than that in the case of isotropy having almost no difference in coercive force, which is preferable. A material having magnetic anisotropy in a plane has a difference in coercivity according to the in-plane direction, and the minimum value of coercivity is smaller than that of a material having magnetic anisotropy. This is preferable because the hysteresis loss is reduced and the magnetic permeability is improved.

The larger the ratio of difference in coercive force due to the orientation in the above-mentioned plane (plane parallel to the flat surface of the flat magnetic metal particles) of the powder compact is, the more preferable is 1% or more. The ratio of the difference in coercive force is more preferably 10% or more, still more preferably 50% or more, and still more preferably 100% or more. The ratio of the difference in coercive force here is defined as (hc (max) -hc (min))/hc (min) × 100 (%) using the coercive force hc (max) which is the largest and the coercive force hc (min) which is the smallest in the flat surface.

The coercive force can be easily evaluated by using a Vibration Sample Magnetometer (VSM) or the like. When the coercive force is low, the coercive force of 0.1Oe or less can be measured by using a low-magnetic-field unit. The measurement is performed by changing the direction in the above-mentioned plane of the powder compact (in a plane parallel to the flat surface of the flat magnetic metal particles) with respect to the direction of the measurement magnetic field.

In the calculation of the coercive force, a value obtained by dividing the difference between the magnetic fields at 2 points (the magnetic fields H1 and H2 in which the magnetization becomes zero) intersecting the horizontal axis by 2 (that is, a value calculated from the coercive force | H2 to H1 |/2) can be used.

From the viewpoint of imparting magnetic anisotropy, it is preferable to align the magnetic metal particles in the direction of the maximum length thereof. Whether or not the maximum length directions are aligned is determined by observing the magnetic metal particles contained in the powder compact with a TEM, SEM, optical microscope, or the like, determining the angle formed by the maximum length direction and an arbitrarily determined reference line, and determining the degree of unevenness. It is preferable to determine the average degree of unevenness with respect to 20 or more flat magnetic metal particles, and in the case where 20 or more flat magnetic metal particles cannot be observed, it is preferable to observe as many flat magnetic metal particles as possible and determine the average degree of unevenness with respect to them. In the present specification, when the degree of unevenness falls within a range of ± 30 °, it is referred to that the maximum length directions coincide. The degree of unevenness is more preferably within a range of ± 20 °, and still more preferably within a range of ± 10 °. This is preferable because the magnetic anisotropy of the powder compact can be easily imparted. It is further preferable that the first direction of one or both of the plurality of concave portions and the plurality of convex portions in the flat surface is aligned in the maximum length direction. This is preferable because the magnetic anisotropy can be given to a large degree.

In the dust material, the "alignment ratio" in which the approximate first direction is aligned in the second direction is preferably 30% or more. More preferably 50% or more, and still more preferably 75% or more. This is preferable because the magnetic anisotropy is appropriately increased and the magnetic properties are improved as described above. First, for all the flat magnetic metal particles evaluated in advance, the direction in which the arrangement direction of the concave portions or convex portions of each flat magnetic metal particle is the largest is defined as a first direction, and the first direction of each flat magnetic metal particle is defined as a second direction in which the entire powder compact is the largest. Next, a direction obtained by dividing the angle of 360 degrees by an angle of 45 degrees with respect to the second direction is determined. Next, the first direction of each flat magnetic metal particle is classified into which angular direction the first direction is most closely aligned, and this direction is defined as "approximate first direction". That is, the direction is classified into 4 of a 0-degree direction, a 45-degree direction, a 90-degree direction, and a 135-degree direction. The ratio at which the approximate first direction is aligned in the same direction with respect to the second direction is defined as "alignment ratio". In the evaluation of the "alignment ratio", 4 adjacent flat magnetic metal particles were selected in order, and the 4 were evaluated. The average value is used as the alignment ratio by repeating the above steps at least 3 times (preferably 5 times or more, for example, more preferably 10 times or more). Note that the flat magnetic metal particles in which the direction of the concave portion or the convex portion cannot be discriminated were excluded from the evaluation, and the evaluation of the flat magnetic metal particles in close proximity thereto was performed. For example, in the flat magnetic metal particles obtained by pulverizing the ribbon synthesized by the single-roll quenching apparatus, there are many cases where only one flat surface has concave portions or convex portions, and the other flat surface does not have concave portions or convex portions. When such flat magnetic metal particles are observed by SEM, the probability that a flat surface without concave portions or convex portions is visible on the observation screen may be about half (in this case, the flat surface on the back side should have concave portions or convex portions, but this is not the case in the above evaluation).

In addition, it is preferable that the most approximate first direction is aligned in the direction of the easy magnetization axis of the powder compact material. That is, the easy magnetization axis of the dust material is preferably parallel to the second direction. The longitudinal direction in which the recesses or projections are arranged is preferably a direction in which magnetization is easy to be caused by the effect of shape magnetic anisotropy, and therefore, when the direction is aligned to be the axis of easy magnetization, magnetic anisotropy is easily imparted.

Preferably, a part of the inclusion phase is attached along the first direction. In other words, it is preferable that a part of the inclusion phase is attached along the direction of the concave or convex portions of the flat magnetic metal particles on the flat surface. This is preferable because magnetic anisotropy is easily induced in one direction. Such adhesion of the inclusion phase is preferable because it improves the adhesion between the flat magnetic metal particles, thereby improving the mechanical properties such as strength and hardness, and the thermal stability. In addition, the inclusion phase preferably includes a particulate phase. This makes it easy to appropriately maintain the adhesion between the flat magnetic metal particles in an appropriate state, and is preferable because strain is reduced (stress applied to the flat magnetic metal particles is relaxed by having a particulate inclusion phase between the flat magnetic metal particles), and the coercive force is reduced (hysteresis loss is reduced, and magnetic permeability is increased).

Fig. 11 is a schematic view showing a method for producing a powder compact according to embodiment 3. Fig. 12 is a graph schematically showing an example of the temperature and pressure at the time of production in embodiment 3. Here, production of a green compact by uniaxial press molding using a die is assumed. In the comparative method, a thermoplastic inclusion phase such as a polyimide resin is inserted between flat magnetic metal particles, and pressure molding is performed while heating to a temperature at or above the softening point of the inclusion phase using the mold. The magnitude of the applied pressure is fixed as shown in the left diagram of fig. 12. In this case, there are the following problems: while raising the temperature toIf the temperature is too high, the fluidity of the inclusion phase increases, and the inclusion phase flows out due to the pressure during the press molding, so that the effect of bonding the flat magnetic metal particles to each other is reduced, and the strength of the powder compact is reduced. Then, in the present embodiment, as shown in the right diagram of fig. 12, the heating is performed to a temperature (T in the right diagram of fig. 12) at or above the softening point of the above-mentioned inclusion phase₁) Simultaneously with a pressure P₁After the pressure molding, the temperature is further raised to T which is not less than the melting point of the inclusion phase₂Until now, for example, melting occurs, and at the same time, for example, the pressure of the press molding is temporarily released and reduced to P₂. Note that, here, P is₂It may be zero or may be a limited pressure to such an extent that the outflow of the inclusion phase is not caused. At this time, in the case of the powder compact material as in the present embodiment using flat magnetic metal particles, the above-described inclusion phase melts, and the volume expands due to the spring back effect derived from the flat shape. However, it is considered that the above-mentioned inclusion phase melted at this time wets and spreads uniformly on the surface of the flat magnetic metal particles. Thereafter, the temperature is increased to a temperature T above the softening point₃Then, at a pressure P₃The volume expanded by the springback is contracted again by the press molding, and the compression molding is performed to densify the material. This can suppress the outflow of the inclusion phase and improve the adhesion between the surface of the flat magnetic metal particles and the inclusion phase, thereby enabling the production of a high-strength green compact. Needless to say, the powder compact of the present embodiment can be preferably produced without depending on uniaxial press molding using a die.

Fig. 13 is a microscope (SEM) photograph of a predetermined cross section of the powder compact according to embodiment 3. A microscope (SEM) photograph of a cross section of the comparative dust material is shown on the left side of fig. 13. The void part was observed at the boundary between the flat surface of the flat magnetic metal particle and the inclusion phase. The void portion is formed along the flat surface. Since the void portion is provided, there is a portion where the flat magnetic metal particles and the inclusion phase are not bonded. Since the strength of the portion where the flat magnetic metal particles and the inclusion phase are not bonded is low, the strength of the dust material is reduced. In contrast, in the dust material of the embodiment shown in the right side of fig. 12, the boundary between the flat surface of the flat magnetic metal particles and the inclusion phase has few voids, and the inclusion phase is adhered to many sites. The strength of the dust material is improved by the large number of portions where the flat surfaces of the flat magnetic metal particles are bonded to the inclusion phase. Specifically, when the length of the void portion to which the inclusion phase is not bonded is 20% or less on average of the length of the flat magnetic metal particles with respect to the length of the flat surface in the case of observing the magnetic powder material with a microscope from a direction parallel to the flat surface, a high-strength powder material can be obtained. Preferably, the length of the void portion is 10% or less. More preferably, the length of the void portion is 5% or less. With the present embodiment, it becomes possible to manufacture and provide a dust material having high strength.

Fig. 14 is a schematic view showing a method for producing a powder compact according to another embodiment of embodiment 3. Among them, for example, a thermosetting inclusion phase such as bismaleimide is used. And, at a pressure P₄(pressure P)₄Zero) is added to the thermosetting resin composition, and the temperature is increased to a temperature higher than the melting point of the thermosetting inclusion phase. In which the inclusion phase wets and spreads uniformly. In the case of using a thermosetting inclusion phase, the curing of the inclusion phase proceeds little by little. And, after the solidification of the inclusion phase has proceeded, the pressure is made to be from P₄Increase to P₅. Thereafter, the pressure is reduced to P₆(pressure P)₆Or may be zero). In such a method, the powder compact of the present embodiment can also be preferably manufactured.

The ratio of the length of the void portion to the length of the flat surface can be determined from an observation image obtained by using, for example, a Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy (SEM-EDX), a Transmission Electron Microscope-Energy Dispersive X-ray Spectroscopy (TEM-EDX), or the like.

Fig. 15 is a schematic view showing the lengths of the flat surface and the void part in a predetermined cross section of the powder compact according to embodiment 3. For example, a method of calculating the ratio of the length of the void portion to the length of the flat surface using SEM-EDX will be described below. First, a conductive coating such as carbon is formed on the surface of the compact to be observed, and a predetermined cross section perpendicular to the flat surface of the flat magnetic metal particles is observed. At this time, the average length of the flat magnetic metal particles is measured for 50 or more flat magnetic metal particles to calculate the distribution of the average length, and the flat magnetic metal particles having an average length falling within a range of ± 20% from the average in the distribution of the average length of the flat magnetic metal particles are selected as the observation target. Then, the obtained SEM image was set to a magnification of a degree to accommodate the entire length of the flat surface of the observation target particle, and an SEM-EDX image was obtained. In the SEM-EDX image, a region containing 1 element of any of iron (Fe), cobalt (Co), and nickel (Ni) as a main component is defined as a magnetic metal phase, a region containing 1 element of oxygen (O), carbon (C), nitrogen (N), and fluorine (F) more than the magnetic metal phase is defined as an inclusion phase, and a region containing no element (or only a detection limit or less) is defined as a void. A portion where a void exists at the interface between the magnetic metal phase and the inclusion phase and the magnetic metal phase is not in contact with the inclusion phase is defined as a void portion. The length of the flat surface of the flat magnetic metal particles and the length of the void portion in the flat surface in which the inclusion phase is not connected in the observation image were measured. The length of the flat surface and the length of the gap portion are measured along the curve of the flat surface. The length of the curve may be measured physically on the SEM image by using a measuring instrument, or may be measured by a method such as detecting a smooth boundary line by a boundary line detection algorithm and calculating the length of the boundary line if the image is obtained electronically. However, as shown in the schematic diagram on the left side of fig. 15, the length of the void portion is measured only at a portion where the flat surface and the inclusion phase do not contact each other, regardless of the shape of the void. In addition, when the flat surface has very fine irregularities, the measurement is performed as the length of a curve that smoothly approximates the portion as shown in the right side of fig. 15. In an observation image obtained by observing at least 20 or more flat magnetic metal particles satisfying the above-described conditions, the total length of the flat surface and the length of the void portion are measured, and the value obtained by dividing the total length of the flat surface by the total length of the void portion is calculated as the length ratio of the void portion to the flat surface in the powder compact. When 20 or more flat magnetic metal particles cannot be observed, it is preferable to observe as many flat magnetic metal particles as possible and judge the average degree of unevenness.

The average orientation angle between the flat surface and the plane of the powder compact can be calculated by the following method using SEM, for example, in the case of a powder compact containing flat magnetic metal particles having an average thickness of 10 to 20 μm and an average value of the ratio of the average length to the thickness in the flat surface of about 5 to 20. First, an SEM-EDX image of an observation area of 500. mu. m.times.500. mu.m was obtained. The observation area may be appropriately changed within a common knowledge range depending on the size of the flat magnetic metal particles (average thickness, average value of the ratio of the average length to the thickness in the flat surface), but it is preferable to select an area containing 20 or more flat magnetic metal particles at least in the observation area. In the obtained SEM-EDX image, a region containing any 1 element of iron (Fe), cobalt (Co), and nickel (Ni) as a main component was identified as flat magnetic metal particles. Considering a rectangle having the smallest area among rectangles circumscribing the flat magnetic metal particles, an angle formed in a longitudinal direction of the rectangle with respect to a plane of the powder compact is defined as an orientation angle of the flat magnetic metal particles. The orientation angle of the flat magnetic metal particles is calculated for all the flat magnetic metal particles in the same observation field, and the average value of the remaining values excluding the maximum value and the minimum value is set as the orientation angle of the observation target surface. However, flat magnetic metal particles may include particles that are very difficult to recognize, and this case may be excluded from the observation target within the scope of common knowledge. By the same calculation method, the orientation angles are calculated for all other planes of the powder compact, and the orientation angle of the plane having the smallest orientation angle is defined as the orientation angle of the powder compact.

The lattice mismatch ratio between the inclusion phase and the flat magnetic metal particles is preferably 0.1% to 50%. This is preferable because the magnetic anisotropy is appropriately large and easily imparted, and the magnetic properties described above are improved. In order to set the lattice mismatch to the above range, it can be achieved by selecting a combination of the composition of the inclusion phase and the composition of the flat magnetic metal particles 10. For example, Ni of fcc structure has a lattice constant ofMgO of NaCl type structure has a lattice constant ofThe lattice mismatch between the two is (4.21-3.52)/3.52 × 100 ═ 20%. That is, the lattice mismatch can be set to 20% by setting the main composition of the flat magnetic metal particles to Ni having an fcc structure and the inclusion phase 20 to MgO. By selecting the combination of the main composition of the flat magnetic metal particles and the main composition of the inclusion phase in this manner, the lattice mismatch can be set to the above range.

The inclusion phase includes at least 1 second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N), and fluorine (F). This can increase the resistance. The electrical resistivity of the inclusion phase is preferably higher than that of the flat magnetic metal particles. This can reduce eddy current loss of the flat magnetic metal particles. The inclusion phase is preferably present by surrounding the flat magnetic metal particles, since the oxidation resistance and thermal stability of the flat magnetic metal particles can be improved. Among them, an oxygen-containing inclusion phase is more preferable from the viewpoint of high oxidation resistance and high thermal stability. The inclusion phase also plays a role of mechanically bonding the flat magnetic metal particles to each other, and is therefore preferable from the viewpoint of high strength.

The inclusion phase may also include at least 1 of 3 "oxides having a eutectic system", or "resins containing", or "magnetic metals selected from at least 1 of Fe, Co, and Ni". These points will be explained below.

First, the "case of oxide having a eutectic system in the inclusion phase" of the 1 st will be described. In this case, the inclusion phase contains an oxide having an eutectic system containing at least 2 third elements selected from the group consisting of B (boron), Si (silicon), Cr (chromium), Mo (molybdenum), Nb (niobium), Li (lithium), Ba (barium), Zn (zinc), La (lanthanum), P (phosphorus), Al (aluminum), Ge (germanium), W (tungsten), Na (sodium), Ti (titanium), As (arsenic), V (vanadium), Ca (calcium), Bi (bismuth), Pb (lead), Te (tellurium), and Sn (tin). Particularly preferred is a eutectic system containing at least 2 elements selected from B, Bi, Si, Zn and Pb. This makes it possible to enhance the adhesion between the flat magnetic metal particles and the inclusion phase (increase the bonding strength), and to easily improve the mechanical properties such as thermal stability, strength, and toughness.

The oxide having the eutectic system has a softening point of preferably 200 to 600 ℃, more preferably 400 to 500 ℃. More preferably, the oxide has a eutectic system containing at least 2 elements of B, Bi, Si, Zn, and Pb, and the softening point is preferably 400 to 500 ℃. As a result, the flat magnetic metal particles and the eutectic oxide are firmly bonded to each other, and the mechanical properties such as thermal stability, strength, and toughness are easily improved. When the flat magnetic metal particles are integrated with the oxide having the eutectic system, the flat magnetic metal particles are integrated with the oxide having the eutectic system while being heat-treated at a temperature near the softening point of the oxide having the eutectic system, preferably at a temperature slightly higher than the softening point, whereby the adhesion between the flat magnetic metal particles and the oxide having the eutectic system can be improved, and the mechanical properties can be improved. Generally, the higher the temperature of the heat treatment is, the more the adhesion between the flat magnetic metal particles and the oxide having the eutectic system is improved, and the more the mechanical properties are improved. However, if the temperature of the heat treatment is too high, the coefficient of thermal expansion increases, and therefore the adhesion between the flat magnetic metal particles and the oxide having the eutectic system described above may be rather reduced (if the difference between the coefficient of thermal expansion of the flat magnetic metal particles and the coefficient of thermal expansion of the oxide having the eutectic system described above is large, the adhesion may be further reduced). When the crystallinity of the flat magnetic metal particles is amorphous or amorphous, crystallization proceeds and the coercive force increases when the temperature of the heat treatment is high, which is not preferable. Therefore, in order to achieve both of the mechanical properties and the coercive force properties, the eutectic oxide is preferably integrated by heat treatment at a temperature in the vicinity of the softening point of the eutectic oxide, preferably at a temperature slightly higher than the softening point, with the softening point of the eutectic oxide set to 200 to 600 ℃, more preferably 400 to 500 ℃. In addition, the temperature at which the integrated material is actually used in the apparatus or system is preferably used at a temperature lower than the softening point.

Further, the oxide having the eutectic system preferably has a glass transition temperature. Further, the thermal expansion coefficient of the oxide having the eutectic system is preferably 0.5 × 10^-6/℃～40×10^-6V. C. As a result, the flat magnetic metal particles 10 and the eutectic oxide are firmly bonded to each other, and the mechanical properties such as thermal stability, strength, and toughness are easily improved.

More preferably, the eutectic particles are contained in at least 1 particle form (preferably spherical form) having a particle diameter of 10nm to 10 μm. The eutectic particles are composed of the same material as the oxide having the eutectic system as described above except for the particle shape. In some cases, voids may be present in the powder compact, and it can be easily observed that a part of the oxide having the eutectic system is present in a particulate form, preferably a spherical form. Even when there is no void, the interface of the particle or the sphere can be easily discriminated. The particle diameter of the eutectic particles is more preferably 10nm to 1 μm, and still more preferably 10nm to 100 nm. As a result, the adhesion between the flat magnetic metal particles can be maintained during the heat treatment, and the strain applied to the flat magnetic metal particles can be reduced by appropriately relaxing the stress, thereby reducing the coercive force. This also reduces hysteresis loss and improves magnetic permeability. The particle size of the eutectic particles can be measured by TEM or SEM observation.

The inclusion phase preferably further includes intermediate inclusion particles having a softening point higher than that of the oxide having the eutectic system, more preferably a softening point higher than 600 ℃, and containing at least 1 element selected from the group consisting of O (oxygen), C (carbon), N (nitrogen), and F (fluorine). By interposing particles between the flat magnetic metal particles, when the powder compact material is exposed to a high temperature, the flat magnetic metal particles can be prevented from thermally fusing with each other and deteriorating the characteristics. That is, the presence of intermediate inclusion particles is preferred mainly due to thermal stability. The thermal stability can be further improved by the softening point of the interstitial particles being higher than the softening point of the oxide having the eutectic system, and more preferably, the softening point being 600 ℃.

The intermediate inclusion particles preferably contain at least 1 nonmagnetic metal selected from the group consisting of Mg, Al, Si, Ca, Zr, Ti, Hf, Zn, Mn, Ba, Sr, Cr, Mo, Ag, Ga, Sc, V, Y, Nb, Pb, Cu, In, Sn, and rare earth elements, and at least 1 element selected from the group consisting of O (oxygen), C (carbon), N (nitrogen), and F (fluorine). More preferably, from the viewpoint of high oxidation resistance and high thermal stability, an oxide or a composite oxide containing oxygen is more preferred. In particular, alumina (Al) is preferable from the viewpoints of high oxidation resistance and high thermal stability₂O₃) Silicon dioxide (SiO)₂) Titanium oxide (TiO)₂) Zirconium oxide (ZrO)₃) And composite oxides such as Al-Si-O.

Examples of the method for producing a powder compact containing intermediate inclusion particles include the following methods: flat magnetic metal particles and intermediate inclusion particles (alumina (Al)₂O₃) Particles, silicon dioxide (SiO)₂) Particles, titanium oxide (TiO)₂) Particles, zirconium oxide (ZrO)₃) Particles, etc.) are mixed by a ball mill or the like to be dispersed, and then integrated by press molding or the like. The method of dispersion is not particularly limited as long as it is a method capable of dispersing the dispersion appropriately.

Next, the 2 nd "case where the inclusion phase contains a resin" will be described. In this case, the resin is not particularly limited, but a polyester resin, a polyethylene resin, a polystyrene resin, a polyvinyl chloride resin, a polyvinyl butyral resin, a polyvinyl alcohol resin, a polybutadiene resin, a teflon (registered trademark, polytetrafluoroethylene) resin, a polyurethane resin, a cellulose resin, an ABS resin, a nitrile-butadiene rubber, a styrene-butadiene rubber, a silicone resin, another synthetic rubber, a natural rubber, an epoxy resin, a phenol resin, an allyl resin, a polybenzimidazole resin, an amide resin, a polyimide resin, a polyamideimide resin, or a copolymer thereof may be used. In particular, in order to achieve high thermal stability, it is preferable to contain a silicone resin or a polyimide resin having high heat resistance. This makes it possible to firmly bond the flat magnetic metal particles and the inclusion phase, and to easily improve the mechanical properties such as thermal stability, strength, and toughness.

The weight loss rate of the resin after heating at 180 ℃ for 3000 hours in an atmospheric atmosphere is preferably 5% or less, more preferably 3% or less, still more preferably 1% or less, and still more preferably 0.1% or less. The weight loss rate after heating at 220 ℃ for 200 hours in the air atmosphere is preferably 5% or less, more preferably 3% or less, still more preferably 1% or less, and yet more preferably 0.1% or less. The weight loss rate after heating at 250 ℃ for 200 hours in an air atmosphere is preferably 5% or less, more preferably 3% or less, still more preferably 1% or less, and yet more preferably 0.1% or less. These weight loss ratios were evaluated using an unused material. The unused state is a state in which the molded article can be used, and the molded article is not exposed to heat (for example, heat at a temperature of 40 degrees or higher), a chemical agent, solar energy (ultraviolet rays), or the like. The weight loss rate was set to a value calculated from the mass before and after heating by the following formula: weight loss ratio (%) [ mass before heating (g) -mass after heating (g) ]/mass before heating (g) × 100. The strength after heating at 180 ℃ for 20000 hours in an atmospheric atmosphere is preferably at least half of the strength before heating. Further preferably, the strength after heating at 220 ℃ for 20000 hours in an atmospheric atmosphere is preferably at least half of the strength before heating. Further, H species specified in Japanese Industrial Standards (JIS) are preferably satisfied. Particularly, it is preferable to satisfy heat resistance capable of withstanding a maximum temperature of 180 ℃. Further preferably, H species specified in the national iron standard (JRE) are satisfied. Particularly, it is preferable that the heat resistance is a heat resistance which can withstand a temperature rise of 180 ℃ relative to the ambient temperature (standard: 25 ℃ C., maximum: 40 ℃ C.). Preferred resins include polysulfone, polyethersulfone, polyphenylene sulfide, polyether ether ketone, aromatic polyimide, aromatic polyamide, aromatic polyamideimide, polybenzoxazole, fluorine resin, silicone resin, liquid crystal polymer, and the like. These resins are preferred because they have high intermolecular cohesive force and therefore have high heat resistance. Among these, aromatic polyimide and polybenzoxazole are preferred because they have a high proportion of rigid units in the molecule and therefore have high heat resistance. In addition, a thermoplastic resin is preferable. The above-described regulation of the heating weight loss rate, the regulation of the strength, and the regulation of the type of the resin are effective for improving the heat resistance of the resin. Further, these are preferable because, when a powder compact made of a plurality of flat magnetic metal particles and an inclusion phase (here, a resin) is formed, the heat resistance as the powder compact is improved (thermal stability is improved), and mechanical properties such as strength and toughness after exposure to a high temperature (for example, 200 ℃ and 250 ℃ described above) or at a high temperature (for example, 200 ℃ and 250 ℃ described above) are easily improved. Further, since many inclusion phases surround the flat magnetic metal particles even after heating, the oxidation resistance is excellent, and deterioration of magnetic characteristics due to oxidation of the flat magnetic metal particles is less likely to occur, which is preferable.

The weight loss rate of the powder compact after heating at 180 ℃ for 3000 hours is preferably 5% or less, more preferably 3% or less, even more preferably 1% or less, and even more preferably 0.1% or less. The weight loss rate of the powder compact after heating at 220 ℃ for 3000 hours is preferably 5% or less, more preferably 3% or less, even more preferably 1% or less, and even more preferably 0.1% or less. The weight loss of the powder material after heating at 250 ℃ for 200 hours in an air atmosphere is preferably 5% or less, more preferably 3% or less, still more preferably 1% or less, and yet more preferably 0.1% or less. The weight loss rate was evaluated in the same manner as in the case of the above-described resin. The strength of the powder material after heating at 180 ℃ for 20000 hours in an atmospheric atmosphere is preferably at least half of the strength before heating. Further preferably, the strength of the powder compact after heating at 220 ℃ for 20000 hours in an atmospheric atmosphere is preferably at least half of the strength before heating. Further, H types specified in Japanese Industrial Standards (JIS) are preferably satisfied. Particularly, it is preferable to satisfy heat resistance capable of withstanding a maximum temperature of 180 ℃. Further preferably, H species specified in the national iron standard (JRE) are satisfied. Particularly, it is preferable to satisfy heat resistance capable of withstanding a temperature rise of 180 ℃ relative to the ambient temperature (standard: 25 ℃ C., maximum: 40 ℃ C.). The above-described regulation of the heating weight loss rate, the regulation of the strength, and the regulation of the resin type are effective for improving the heat resistance of the powder compact material, and a highly reliable material can be realized. Further, the powder material is preferably improved in heat resistance (improved in thermal stability) because it is easy to improve mechanical properties such as strength and toughness after exposure to high temperature (for example, 200 ℃ C. and 250 ℃ C. described above) or at high temperature (for example, 200 ℃ C. and 250 ℃ C. described above). Further, since many inclusion phases surround the flat magnetic metal particles even after heating, the oxidation resistance is excellent, and deterioration of magnetic characteristics due to oxidation of the flat magnetic metal particles is less likely to occur, which is preferable.

Further, it is preferable to contain a crystalline resin having no glass transition temperature at or below the thermal decomposition temperature. Further, the resin preferably contains a resin having a glass transition temperature of 180 ℃ or higher, more preferably contains a resin having a glass transition temperature of 220 ℃ or higher, and still more preferably contains a resin having a glass transition temperature of 250 ℃ or higher. Generally, the higher the temperature of the heat treatment becomes, the larger the crystal particle diameter of the flat magnetic metal particles becomes. Therefore, when it is necessary to reduce the crystal particle diameter of the flat magnetic metal particles, the glass transition temperature of the resin used is preferably not excessively high, and more specifically, 600 ℃. The crystalline resin having no glass transition temperature equal to or lower than the thermal decomposition temperature preferably contains a resin having a glass transition temperature of 180 ℃ or higher, and more preferably contains a resin having a glass transition temperature of 220 ℃ or higher. Specifically, the polyimide preferably contains a polyimide having a glass transition temperature of 180 ℃ or higher, more preferably contains a polyimide having a glass transition temperature of 220 ℃ or higher, and still more preferably contains a thermoplastic polyimide. This makes it easy to cause fusion bonding with the magnetic metal particles, and is particularly suitable for powder molding. As the thermoplastic polyimide, thermoplastic polyimides having an imide bond in a polymer chain, such as thermoplastic aromatic polyimides, thermoplastic aromatic polyamideimides, thermoplastic aromatic polyetherimides, thermoplastic aromatic polyesterimides, and thermoplastic aromatic polyimide siloxanes, are preferable. Among these, the glass transition temperature of 250 ℃ or higher is preferable because the heat resistance is higher.

Aromatic polyimides and polybenzoxazoles have a planar structure in which an aromatic ring is directly bonded to a heterocyclic ring, and they are immobilized by pi-pi stacking, thereby exhibiting high heat resistance. This can increase the glass transition temperature and improve thermal stability. Further, it is preferable to introduce a suitable amount of a buckling unit such as an ether bond into the molecular structure, since the glass transition temperature can be easily adjusted to a desired value. Among them, when the benzene ring structure of the acid anhydride-derived unit constituting the imide polymer is any of biphenyl, triphenyl, and tetraphenyl, it is preferable from the viewpoint of strength. Since the symmetric structure between imide groups that affects heat resistance is not impaired and the orientation also extends over long distances, the material strength is also improved. The structure of the preferred aromatic polyimide is represented by the following chemical formula (1). In other words, the polyimide resin of the present embodiment includes a repeating unit represented by the following chemical formula (1).

In the chemical formula (1), R represents any one of biphenyl, triphenyl and tetraphenyl, and R' represents a structure having at least 1 or more aromatic rings in the structure.

When the properties (weight reduction rate, resin type, glass transition temperature, molecular structure, and the like) of the inclusion phase (here, resin) as a constituent component thereof were determined from the green compact, only the resin portion was cut out of the green compact, and various property evaluations were performed. When it is not possible to determine whether the resin is a resin by visual observation, the resin is distinguished from the magnetic metal particles by elemental analysis using EDX or the like.

The larger the content of the resin in the entire powder compact material is, the more the polymer can be smoothly connected between the polymer wetting (covering) the flat magnetic metal particles and the polymer wetting (covering) the adjacent flat magnetic metal particles, and the mechanical properties such as strength are improved. Further, the resistivity is also high, and the eddy current loss of the powder compact can be reduced, which is preferable. On the other hand, the larger the resin content, the smaller the proportion of flat magnetic metal particles, and therefore the saturation magnetization of the powder material decreases, and the magnetic permeability also decreases, which is not preferable. In order to achieve a material that is well balanced in terms of mechanical properties such as strength, electrical resistivity, eddy current loss, saturation magnetization, and magnetic permeability, the content of the resin in the entire powder material is preferably 93 wt% or less, more preferably 86 wt% or less, even more preferably 2 wt% to 67 wt%, and even more preferably 2 wt% to 43 wt%. The content of the flat magnetic metal particles is preferably 7% by weight or more, more preferably 14% by weight or more, still more preferably 33% by weight to 98% by weight, and still more preferably 57% by weight to 98% by weight. In addition, the flat magnetic metal particles preferably have an appropriately large particle diameter because the surface area becomes large and the amount of resin required increases dramatically when the particle diameter becomes small. This makes it possible to magnetize the powder compact material at a high saturation level, to increase the magnetic permeability, and is advantageous for the system to be small in size and high in output.

Next, the 3 rd "case where the inclusion phase contains at least 1 magnetic metal selected from Fe, Co, and Ni and has magnetism" will be described. In this case, the inclusion phase is preferably magnetic, since the flat magnetic metal particles are easily magnetically bonded to each other, and the magnetic permeability is improved. Further, since the magnetic domain structure is stabilized, the frequency characteristic of magnetic permeability is also improved, which is preferable. Here, the term "magnetism" refers to ferromagnetism, ferrimagnetism, weak magnetism, antiferromagnetic property, and the like. Particularly, in the case of ferromagnetism or ferrimagnetism, the magnetic binding force is preferably improved. The magnetic properties of the inclusion phase can be evaluated by using a Vibrating Sample Magnetometer (VSM) or the like. The point that the inclusion phase contains at least 1 magnetic metal selected from Fe, Co, and Ni and has magnetism can be easily examined using EDX or the like.

While 3 forms of the inclusion phase have been described above, it is preferable to satisfy at least 1 of these 3 forms, and 2 or more, and further 3 forms may be all satisfied. "the case where the inclusion phase has a eutectic oxide" (case 1) is slightly inferior to the case where the inclusion phase is a resin (case 2) in terms of mechanical properties such as strength, but is preferable from the viewpoint that strain is easily released, and particularly, low coercive force is easily achieved (this is preferable because low hysteresis loss and high magnetic permeability are easily achieved). In addition, it is preferable to use a resin because it has high heat resistance and excellent thermal stability in many cases. On the other hand, the "case where the inclusion phase contains a resin" (case 2) has a disadvantage that the coercive force tends to increase easily because the flat magnetic metal particles are easily stressed (easily strained) because of high adhesion with the resin, but is particularly excellent in mechanical properties such as strength, and is therefore preferable. "the case where the inclusion phase contains at least 1 magnetic metal selected from Fe, Co and Ni and is magnetic" (case 3) is preferable because the flat magnetic metal particles are easily magnetically bonded to each other, and therefore, the magnetic particles are particularly excellent in high magnetic permeability and low coercive force (and thus low hysteresis loss). In view of the above advantages and disadvantages, the present invention can be used separately, and a balanced inclusion phase can be produced by combining several phases.

The flat magnetic metal particles contained in the dust material preferably satisfy the requirements described in embodiments 1 and 2. Since the contents are repeated here, the description is omitted.

In the powder compact, the flat surfaces of the plurality of flat magnetic metal particles are preferably oriented in layers so as to be parallel to each other. This is preferable because the eddy current loss of the powder compact can be reduced. Further, since the back magnetic field can be reduced, the magnetic permeability of the powder compact can be increased, which is preferable. Further, since the ferromagnetic resonance frequency can be increased, the ferromagnetic resonance loss can be reduced, which is preferable. Further, such a laminated structure is preferable because the magnetic domain structure is stabilized and low magnetic loss can be achieved. Wherein, is defined as: the angle between the plane parallel to the flat surface of the flat magnetic metal particles and the plane of the powder compact is oriented as closer to 0 degrees. Specifically, the average value of the angles obtained for a plurality of 10 or more flat magnetic metal particles 10 is preferably 0 to 45 degrees, more preferably 0 to 30 degrees, and still more preferably 0 to 10 degrees.

The powder compact may have a laminated structure including a magnetic layer containing the flat magnetic metal particles and an intermediate layer containing any one of O, C, N. In the magnetic layer, the flat magnetic metal particles are preferably oriented (oriented so that their flat surfaces are parallel to each other). In addition, the magnetic permeability of the intermediate layer is preferably smaller than that of the magnetic layer. These treatments are preferable because a pseudo thin-film laminated structure can be realized and the magnetic permeability in the layer direction can be improved. In addition, such a configuration is preferable because the ferromagnetic resonance frequency can be increased, and the ferromagnetic resonance loss can be reduced. Further, such a laminated structure is preferable because the magnetic domain structure is stabilized and low magnetic loss can be achieved. In order to further improve these effects, it is more preferable that the magnetic permeability of the intermediate layer is smaller than the magnetic permeability of the inclusion phase (inclusion phase in the magnetic layer). This is preferable because the pseudo thin-film laminated structure can further improve the magnetic permeability in the layer direction. Further, since the ferromagnetic resonance frequency can be further increased, the ferromagnetic resonance loss can be reduced, which is preferable.

As described above, according to the present embodiment, a powder compact having excellent magnetic characteristics such as low magnetic loss can be provided.

(embodiment 4)

The system and the equipment of the present embodiment have the dust-pressing material of embodiment 3. Therefore, description of the overlapping contents with those of embodiments 1 to 3 is omitted. The powder compact material component included in the system or the equipment is, for example, a rotating electrical machine (e.g., a motor, a generator, etc.) such as various motors and generators, a core such as a transformer, an inductor, a converter, a choke coil, and a filter, a magnetic wedge (magnetic wedge) for a rotating electrical machine, and the like. Fig. 16 is a conceptual diagram of the motor system of embodiment 4. The motor system is an example of a rotating electric machine system. The motor system includes a control system for controlling the rotational speed and electric power (output power) of the motor. As a method of controlling the rotation speed of the motor, there is a control method based on control by a bridge servo circuit, proportional current control, voltage comparison control, frequency synchronization control, Phase Locked Loop (PLL) control, and the like. As an example, fig. 16 shows a control method using a PLL. A motor system for controlling the rotational speed of a motor by using a PLL includes a motor, a rotary encoder for converting a mechanical displacement amount of rotation of the motor into an electric signal and detecting the rotational speed of the motor, a phase comparator for comparing the rotational speed of the motor given by a command with the rotational speed of the motor detected by the rotary encoder and outputting a difference in the rotational speeds, and a controller for controlling the motor so as to reduce the difference in the rotational speeds. On the other hand, as a method of controlling the electric power of the motor, there are control methods such as Pulse Width Modulation (PWM) control, Pulse voltage Amplitude waveform (PAM) control, vector control, Pulse control, bipolar driving, off-Pulse level control, and resistance control. As other control methods, there are control methods such as micro-step drive control, multiphase drive control, inverter control, and switching control. As an example, fig. 16 shows a control method using an inverter. A motor system for controlling electric power of a motor by an inverter includes an ac power supply, a rectifier for converting an output of the ac power supply into a dc current, an inverter circuit for converting the dc current into an ac current having an arbitrary frequency, and a motor controlled by the ac current.

Fig. 17 is a conceptual diagram of the motor according to embodiment 4. The motor 200 is an example of a rotating electrical machine. In the motor 200, a 1 st stator (stator) and a 2 nd rotor (rotor) are arranged. In the figure, the inner rotor type in which the rotor is disposed inside the stator is shown, but the outer rotor type in which the rotor is disposed outside the stator may be used.

Fig. 18 is a conceptual diagram of a motor core (stator) according to embodiment 4. Fig. 19 is a conceptual diagram of a motor core (rotor) according to embodiment 4. As the motor core 300 (core of the motor), cores of the stator and the rotor are matched. This point will be explained below. Fig. 18 is a conceptual illustration of a cross section of the 1 st stator. The 1 st stator has a core and a winding. The winding is wound around a portion of the protrusion of the core provided inside the core. The dust material of embodiment 3 may be disposed within the core. Fig. 19 is a conceptual illustration of a cross section of the 1 st rotor. The 1 st rotor has a core and a winding. The winding is wound around a portion of the protrusion provided in the core outside the core. The dust material of embodiment 3 may be disposed within the core.

Fig. 18 and 19 are views showing an example of the motor to the bottom, and the application target of the dust material is not limited to this. The core for easily conducting magnetic flux can be applied to all kinds of motors.

Fig. 20 is a conceptual diagram of the transformer/converter of embodiment 4. Fig. 21 is a conceptual diagram of an inductor (ring inductor, rod inductor) according to embodiment 4. Fig. 22 is a conceptual diagram of an inductor (chip inductor, planar inductor) according to embodiment 4. They are also merely diagrams that are shown as an example. In the transformer/converter 400 and the inductor 500, similarly to the motor core, a powder material can be applied to all kinds of transformers/converters and inductors in order to facilitate conduction of magnetic flux or to utilize high magnetic permeability.

Fig. 23 is a conceptual diagram of the generator 500 of embodiment 4. The generator 500 is an example of a rotating electric machine. The generator 500 includes either or both of a 2 nd stator (stator) 530 using the powder compact of embodiments 1 to 3 as a core and a 2 nd rotor (rotor) 540 using the powder compact of embodiments 1 to 3 as a core. In the figure, the 2 nd rotor (rotor) 540 is disposed inside the 2 nd stator 530, but may be disposed outside. The 2 nd rotor 540 is connected to a turbine 510 provided at one end of the generator 500 via a shaft 520. The turbine 510 is rotated by a fluid supplied from an outside, not shown, for example. Instead of the turbine that rotates by the fluid, the shaft may be rotated by dynamic rotation such as transmission of regenerative energy of the vehicle. Various known configurations can be employed for the 2 nd stator 530 and the 2 nd rotor 540.

The shaft is in contact with a commutator, not shown, disposed on the opposite side of the 2 nd rotor from the turbine. The electromotive force generated by the rotation of the 2 nd rotor is boosted to a system voltage as electric power of the generator via a phase separation bus not shown and a main transformer not shown, and is transmitted. In the 2 nd rotor, static electricity from the turbine or shaft current generated by the turbine is charged. Therefore, the generator includes a brush for discharging the electricity charged in the 2 nd rotor.

The rotating electric machine according to the present embodiment can be preferably used for railway vehicles. For example, the motor 200 for driving a railway vehicle or the generator 500 for generating electricity for driving a railway vehicle may be preferable.

Fig. 24 is a conceptual diagram showing a relationship between the direction of the magnetic flux and the arrangement direction of the powder compact. First, in both of the domain wall moving type and the rotating magnetization type, it is preferable that flat surfaces of the flat magnetic metal particles included in the powder material are arranged in a direction parallel to each other as much as possible and aligned in a layer shape with respect to the direction of the magnetic flux. This is because the eddy current loss can be reduced by reducing the cross-sectional area of the flat magnetic metal particles penetrating the magnetic flux as much as possible. In addition, in the domain wall moving type, it is preferable that the easy magnetization axis (arrow direction) in the flat surface of the flat magnetic metal particle is arranged in parallel to the direction of the magnetic flux. This is preferable because the coercive force can be further reduced, and the hysteresis loss can be reduced. Further, the magnetic permeability can be preferably increased. In contrast, in the rotating magnetization type, it is preferable that the easy magnetization axis (arrow direction) in the flat surface of the flat magnetic metal particle is arranged perpendicular to the direction of the magnetic flux. This is preferable because the coercive force can be further reduced, and the hysteresis loss can be reduced. That is, it is preferable to grasp the magnetization characteristics of the powder compact and to find out whether the powder compact is of a domain wall moving type or a rotating magnetization type (the determination method is as described above), and then to arrange the powder compact as shown in fig. 18. When the direction of the magnetic flux is complicated, it may be difficult to arrange completely as shown in fig. 18, but it is preferable to arrange as much as possible as shown in fig. 18. The above arrangement method is preferably applied to all the systems and equipment devices (for example, various electric motors, electric generators, and other rotating electric machines (for example, electric motors, electric generators, and the like), transformers, inductors, inverters, choke coils, filters, cores for rotating electric machines, magnetic wedges (wedges), and the like) according to the present embodiment.

To be suitable for use in the system and apparatus, the dust material allows various processes to be performed. For example, in the case of a sintered body, mechanical processing such as grinding or cutting is performed, and in the case of a powder, mixing with a resin such as an epoxy resin or polybutadiene is performed. Further surface treatment is carried out as required. In addition, winding processing is performed as necessary.

According to the system and the facility device of the present embodiment, a motor system, a motor, a transformer, an inverter, an inductor, and a generator having excellent characteristics (high efficiency and low loss) can be realized.

(examples)

Examples 1 to 12 are described below in more detail in comparison with comparative example 1. Table 1 summarizes the ratio of the length of the void portion to the flat surface, the average thickness t of the flat magnetic metal particles, and the average value a of the ratio of the average length to the thickness in the flat surface, for the powder compacts obtained in the examples and comparative examples shown below.

(example 1)

First, a ribbon of Fe — Co — B — Si (Fe: Co: B: Si 552: 23: 19: 6 (atomic%), Fe: Co: 70: 30 (atomic%), and the total amount of additive elements B + Si was 25 atomic% with respect to the total amount of Fe + Co + B + Si) was produced using a single-roll quenching apparatus. The resulting tape is then placed in H₂The heat treatment is carried out in an atmosphere at 300 ℃. Then, the tape is pulverized by a mixer device, and then the pulverized tape is put into a container H₂Heat treatment was carried out in a magnetic field at 400 ℃ in an atmosphere to obtain flat magnetic metal particles. The average thickness t of the obtained flat magnetic metal particles was 10 μm, and the average value a of the ratio of the average length to the thickness in the flat plane was 20. The obtained flat magnetic metal particles were mixed with an inclusion phase (polyimide resin), and subjected to magnetic field molding (orientation of the flat particles) and hot press molding. As the hot press molding conditions, the molding was continuously carried out under 3 stages of conditions of 400 ℃ to 140MPa to 1 hour, 420 ℃ to 0.1MPa to 1 hour, and 400 ℃ to 140MPa to 1 hour. Thereafter, heat treatment was performed in a magnetic field to obtain a powder compact. In the heat treatment in a magnetic field, a magnetic field is applied in the direction of the easy magnetization axis to perform the heat treatment.

(example 2)

The powder compact was the same as in example 1 except that the hot press molding conditions were controlled so that the ratio of the crack portion to the flat surface was the value shown in example 2 of table 1.

(examples 3 to 12)

The examples were conducted in the same manner as examples 1 and 2 except that the average thickness t of the flat magnetic metal particles and the ratio a of the average length to the thickness in the flat surface were the values shown in examples 3 to 12 in table 1.

Comparative example 1

The hot press molding was performed in the same manner as in example 1 except that the hot press molding conditions were controlled so that the ratio of the crack portion to the flat surface of the obtained powder compact was the value shown in comparative example 1 of table 1.

Next, the strength ratio and strength retention ratio of the evaluation materials of examples 1 to 12 and comparative example 1 were evaluated by the following methods. The evaluation results are shown in table 2.

(1) Strength ratio: the flexural strength of the test specimen for evaluation was measured according to the measurement method of JIS Z2248 and expressed as the ratio (i.e., the saturation magnetization of the test specimen for evaluation/the saturation magnetization of comparative example 1) to the flexural strength of the test specimen of comparative example 1. When the test piece for evaluation is small and does not satisfy the test piece shape defined in JIS Z2248, the flexural strength of the test piece for evaluation is estimated from a calibration curve prepared using a test piece of the same size whose flexural strength is known, and this is set as the value of the flexural strength of the test piece.

(2) Strength retention ratio: the flexural strength of the evaluation sample was measured. After heating at 180 ℃ for 3000 hours in the air, the flexural strength of the evaluation sample was measured again. From this, the strength retention ratio (bending strength after heating/bending strength before heating × 100 (%)) was obtained.

[ Table 1]

[ Table 2]

As is clear from Table 1, the ratio of the length of the void part to the flat surface of the green compacts of examples 1 to 12 was 20% or less. On the other hand, in comparative example 1, the ratio of the length of the void portion to the flat surface is not included in the above range.

As indicated by table 2, it is known that: the powder compacts of examples 1 to 12 were superior to the powder compact of comparative example 1 in strength ratio and strength retention rate. This is because the powder compact of comparative example 1 had many void sites, and therefore the cohesive force between the flat magnetic metal particles was insufficient. Knowing: in examples 1 to 12, since the strength ratio was excellent, the strength retention was also improved as compared with comparative example 1. As described above, a significant effect is obtained only when the ratio of the length of the void portion to the flat surface is within the range of 20% or less, a high strength ratio can be realized, and an effect of improving the strength retention rate is also obtained. That is, it was found that the composition was excellent in thermal stability and mechanical properties (strength and hardness). In addition, the dust material of the embodiment can be applied to a complicated shape.

Several embodiments and examples of the present invention have been described, but these embodiments and examples are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be implemented in other various ways, and various omissions, substitutions, and changes may be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

The above embodiments may be summarized as follows.

Technical solution 1

A powder compact comprising a plurality of flat magnetic metal particles and an inclusion phase, wherein the flat magnetic metal particles have a flat surface and a magnetic metal phase containing 1 first element selected from the group consisting of Fe, Co and Ni, the average thickness is 10nm to 100 [ mu ] m, the average value of the ratio of the average length to the thickness in the flat surface is 5 to 10000, and the inclusion phase is present between the flat magnetic metal particles and contains at least 1 second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N) and fluorine (F),

in the powder compact, in a predetermined cross section perpendicular to the flat surface, a void portion is included at a boundary portion between the flat surface of the flat magnetic metal particles and the inclusion phase in contact with the flat surface, and a ratio of a length of the void portion to a length of the flat surface is 20% or less.

Technical solution 2

The powder compact according to claim 1, wherein the powder compact has a difference in coercive force due to direction in a plane thereof.

Technical solution 3

The powder compact according to claim 1 or 2, wherein at least a part of the surface of the flat magnetic metal particles is covered with a coating layer having a thickness of 0.1nm to 1 μm and containing at least 1 of the second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N) and fluorine (F).

Technical solution 4

The powder compact according to any one of claims 1 to 3, wherein the inclusion phase contains a resin having a weight loss rate of 5% or less after heating at 180 ℃ for 3000 hours.

Technical solution 5

The powder compact according to any one of claims 1 to 4, wherein a weight loss rate of the powder compact after heating at 180 ℃ for 3000 hours is 5% or less.

Technical scheme 6

The powder material according to any one of claims 1 to 5, wherein the inclusion phase contains a resin having no glass transition temperature at or below a thermal decomposition temperature.

Technical scheme 7

The powder compact according to any one of claims 1 to 6, wherein the inclusion phase is a polyimide resin.

Technical solution 8

A rotary electric machine comprising the powder compact according to any one of claims 1 to 7.

Technical solution 9

A rotating electrical machine comprising a magnetic wedge comprising the powder compact according to any one of claims 1 to 7.

Technical means 10

A rotating electrical machine comprising a core containing the powder compact according to any one of claims 1 to 7.