Pressed powder materials and rotating motors

Abstract

The pressed powder material of an embodiment of the present invention is a pressed powder material comprising a first magnetic metal particle having a magnetic metal phase containing Fe and Co and a second magnetic metal particle having a magnetic metal phase containing Fe, wherein when the Co amounts of the first and second magnetic metal particles relative to the total amount of Fe and Co are Co1 and Co2 respectively, the ratio of Co2 to Co1 (Co2 / Co1) is 0 to 0.5, the average value of the ratio of the major axis to the minor axis is greater than 2 in the case of the first magnetic metal particle and greater than 1 in the case of the second magnetic metal particle, the second magnetic metal particle exists between the particles of the first magnetic metal particle, and the average value of the major axis of the second magnetic metal particle is the same as or longer than the average value of the major axis of the first magnetic metal particle.

Description

[0001] Citations of related applications

[0002] This application is based on and claims the benefit of priority from Japanese Patent Application No. 2021-046801 (filing date: March 22, 2021), the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of the present invention relate to a compressed powder material and a rotating electric machine. Background Art

[0004] Currently, soft magnetic materials are used in components of various systems and equipment such as rotating electrical machines (such as motors, generators, etc.), transformers, inductors, converters, magnetic inks, antenna devices, etc., and are very important materials. Among these components, since the real part of the permeability (real part of relative permeability) μ' of the soft magnetic material is used, it is preferable to control μ' in actual use. In addition, in order to achieve a high-efficiency system, it is preferable to make the material with as low loss as possible. That is, it is preferable to reduce the imaginary part of the permeability (imaginary part of relative permeability) μ" (equivalent to loss) as much as possible. Regarding loss, the loss coefficient tanδ (=μ" / μ'×100(%)) becomes a standard. The smaller μ" is relative to μ', the smaller the loss coefficient tanδ becomes, which is preferable. Therefore, it is preferable to reduce the iron loss under actual operating conditions, that is, it is preferable to reduce eddy current loss, hysteresis loss, strong magnetic resonance loss, and residual loss (other losses) as much as possible. In order to reduce eddy current loss, it is effective to increase resistance, reduce the size of the metal part, or subdivide the magnetic domain structure. In order to reduce hysteresis loss, it is effective to reduce coercive force or increase saturation magnetization. In order to reduce the ferromagnetic resonance loss, it is effective to increase the anisotropic magnetic field of the material and increase the ferromagnetic resonance frequency. In addition, in recent years, due to the increasing demand for processing high-power electricity, it is particularly required to have low losses under operating conditions such as high current and high voltage, where the effective magnetic field applied to the material is large. Therefore, in order to avoid magnetic saturation, the saturation magnetization of the soft magnetic material is preferably as large as possible. Furthermore, in recent years, since the miniaturization of instruments can be achieved by increasing the frequency, the frequency band used by systems and equipment has progressed to higher frequencies, and it has become urgent to develop magnetic materials with high permeability, low loss, and excellent characteristics at high frequencies.

[0005] In addition, in recent years, due to the increasing awareness of energy conservation and environmental issues, there is a demand to improve the efficiency of the system as much as possible. In particular, since the motor system is responsible for the majority of electricity consumption in society, it is very important to increase the efficiency of the motor. Among them, the core of the motor is made of soft magnetic materials, and it is required to increase the magnetic permeability or saturation magnetization of the soft magnetic material as much as possible, or to reduce the loss as much as possible. In addition, the magnetic wedge (magnetic wedge) used in part of the motor is required to reduce the loss as much as possible. It should be noted that the same requirement also exists in systems using converters. In motors or converters, there is a great demand for miniaturization while requiring 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 the saturation magnetization as much as possible. Furthermore, there is a great demand to increase the operating frequency of the system, and it is required to develop materials with low loss in the high frequency band.

[0006] Soft magnetic materials with high permeability and low loss are also used in inductors and antenna devices. In recent years, their use in power inductors for use in power semiconductors has particularly attracted attention. In recent years, the importance of energy conservation and environmental protection has been actively promoted, with demands for reducing CO2 emissions and reducing dependence on fossil fuels. As a result, the development of electric and hybrid vehicles to replace gasoline vehicles is intensifying. Furthermore, technologies that utilize natural energy, such as solar and wind power generation, are considered key technologies for an energy-efficient society, and advanced countries are actively developing these technologies. Furthermore, as environmentally friendly power-saving systems, the importance of building home energy management systems (HEMS) and building and energy management systems (BEMS) is being actively promoted. These systems use smart grids to efficiently control the electricity generated by solar and wind power generation, ensuring efficient supply and demand within homes, offices, and factories. Power semiconductors play a key role in this energy-saving trend. Power semiconductors are semiconductors that efficiently control high power and energy. In addition to individual power semiconductors such as insulated gate bipolar transistors (IGBTs), MOSFETs, power bipolar transistors, and power diodes, they also include power supply circuits for linear regulators, switching regulators, and power management logic LSIs used to control them. Power semiconductors are widely used in all kinds of equipment, including home appliances, computers, automobiles, and railways. Since the popularity of these applications is expected to expand, and the proportion of power semiconductors installed in these devices will increase, the market for power semiconductors is expected to grow significantly in the future. For example, in the inverters installed in many home appliances, it can be said that power semiconductors are basically used, which can achieve significant energy savings. Regarding power semiconductors, Si is currently the mainstream, but for further efficiency and miniaturization of equipment, the use of SiC and GaN is considered effective. Compared with Si, SiC and GaN have larger band gaps and dielectric breakdown electric fields, which can increase the withstand voltage, so the thickness of the components can be reduced. Therefore, the on-state resistance of the semiconductor can be reduced, which is effective for reducing losses and improving efficiency. Furthermore, SiC and GaN, due to their high carrier mobility, enable higher switching frequencies, effectively contributing to device miniaturization. Furthermore, SiC, in particular, has a higher thermal conductivity than Si, resulting in superior heat dissipation, enabling high-temperature operation and simplifying cooling mechanisms, further contributing to miniaturization. With these considerations in mind, the development of SiC and GaN power semiconductors is being actively pursued.However, to achieve this development, the development of power inductor elements used with power semiconductors—specifically, high-permeability soft magnetic materials (high permeability and low loss)—is essential. The required properties for magnetic materials in this context are, of course, high permeability and low magnetic loss within the drive frequency band, but also high saturation magnetization capable of handling large currents. High saturation magnetization reduces the risk of magnetic saturation even when high magnetic fields are applied, thus minimizing the decrease in effective inductance. This improves the device's DC superposition characteristics and enhances system efficiency.

[0007] Furthermore, magnetic materials with high permeability and low loss at high frequencies are expected to be used in high-frequency communication equipment such as antenna devices. One method for miniaturizing and reducing power consumption of antennas is to use an insulating substrate with high magnetic permeability (high permeability and low loss) as the antenna substrate, thereby trapping radio waves from the antenna to the electronic components or substrate within the communication device, thereby transmitting and receiving signals without the radio waves reaching the electronic components or substrate. This method can achieve miniaturization and power consumption of the antenna, while also widening the resonant frequency of the antenna, making it preferable.

[0008] It should be noted that other properties required for integration into the aforementioned systems and devices include high thermal stability, high strength, and high toughness. Furthermore, for compatibility with complex shapes, pressed powder materials are more preferred over plates or strips. However, it is generally known that pressed powder materials degrade in saturation magnetization, magnetic permeability, loss, strength, toughness, hardness, and other characteristics, and improved properties are therefore preferred.

[0009] Next, conventional soft magnetic materials will be described along with their types and problems.

[0010] As an existing soft magnetic material for systems below 10kH, silicon steel sheet (FeSi) can be cited. Silicon steel sheet has a long history and is the material used in the core materials of most rotating motors and converters that handle large amounts of power. The pursuit of higher properties from non-directional silicon steel sheet to directional silicon steel sheet has been progressing compared to when it was first discovered, but in recent years, the improvement in properties has reached its limit. As properties, it is particularly important to simultaneously meet high saturation magnetization, high magnetic permeability, and low loss. In society, research on materials that surpass silicon steel sheet is being actively carried out, focusing on amorphous and nanocrystalline compositions, but a material composition that surpasses silicon steel sheet in all aspects has not yet been found. In addition, research has been conducted on pressed powder materials that can be applied to complex shapes. Pressed powder materials have the disadvantage of poor properties compared to plates or strips.

[0011] Existing soft magnetic materials for 10kHz to 100kHz systems include Sendust (Fe-Si-Al), nanocrystalline Finemet (Fe-Si-B-Cu-Nb), Fe-based or Co-based amorphous / glass ribbon / powder materials, and MnZn-based ferrite materials. However, none of these materials fully meet the requirements of high magnetic permeability, low loss, high saturation magnetization, high thermal stability, high strength, high toughness, and high hardness, and remain insufficient.

[0012] Examples of existing soft magnetic materials for frequencies of 100 kHz or higher (MHz band or higher) include NiZn-based ferrite and hexagonal ferrite. However, these materials have insufficient magnetic properties at high frequencies.

[0013] In view of the above circumstances, it is desirable to develop a magnetic material having high saturation magnetization, high magnetic permeability, low loss, high thermal stability, and excellent mechanical properties. Summary of the Invention

[0014] An object of the present invention is to provide a compacted powder material having excellent magnetic properties and a rotating electrical machine using the compacted powder material.

[0015] The pressed powder material of the embodiment is a pressed powder material comprising a first magnetic metal particle having a magnetic metal phase containing Fe and Co and a second magnetic metal particle having a magnetic metal phase containing Fe, wherein when the Co amounts of the first and second magnetic metal particles relative to the total amount of Fe and Co are Co1 and Co2 respectively, the ratio of Co2 to Co1 (Co2 / Co1) is 0 to 0.5, the average value of the ratio of the major axis to the minor axis is greater than 2 in the case of the first magnetic metal particle and greater than 1 in the case of the second magnetic metal particle, the second magnetic metal particle exists between the particles of the first magnetic metal particle, and the average value of the major axis of the second magnetic metal particle is the same as or longer than the average value of the major axis of the first magnetic metal particle.

[0016] According to the above configuration, a compressed powder material having excellent magnetic properties and a rotating electrical machine using the same can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic cross-sectional view showing the compressed powder material according to the first embodiment.

[0018] Figure 2 This is a schematic diagram for explaining a method for determining the major axis and minor axis of magnetic metal particles in the compacted powder material according to the first embodiment.

[0019] Figure 3A -B is a schematic diagram of magnetic metal particles according to the second embodiment.

[0020] Figure 4 This is a schematic diagram of a motor system according to a fourth embodiment.

[0021] Figure 5 This is a schematic diagram of an electric motor according to a fourth embodiment.

[0022] Figure 6 This is a schematic diagram of a motor core (stator) according to a fourth embodiment.

[0023] Figure 7 This is a schematic diagram of a motor core (rotor) according to a fourth embodiment.

[0024] Figure 8 This is a schematic diagram of a transformer / converter according to a fourth embodiment.

[0025] Figure 9 It is a schematic diagram of an inductor (ring-shaped inductor, rod-shaped inductor) according to a fourth embodiment.

[0026] Figure 10 It is a schematic diagram of a sensor (chip sensor, planar sensor) according to a fourth embodiment.

[0027] Figure 11 This is a schematic diagram of a generator according to a fourth embodiment.

[0028] Explanation of symbols

[0029] 1. Magnetic metal particles

[0030] 2nd magnetic metal particles

[0031] 3 Covering layer

[0032] 10 Magnetic metal particles

[0033] 100 Pressed powder material

[0034] 200 electric motor

[0035] 300 electric movement

[0036] 400 transformers and converters

[0037] 500 sensors DETAILED DESCRIPTION

[0038] Hereinafter, the embodiments will be described using the drawings. It should be noted that in the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0039] (First embodiment)

[0040] The pressed powder material of this embodiment comprises at least two types of magnetic metal particles having different Co contents. The first magnetic metal particle comprises a magnetic metal phase containing Fe and Co, wherein the Co content Co1 is expressed as the amount of Co relative to the total amount of Fe and Co in the magnetic metal phase. The second magnetic metal particle comprises a magnetic metal phase containing Fe, wherein the Co content Co2 is expressed as the amount of Co relative to the total amount of Fe and Co in the magnetic metal phase. The ratio of Co2 to Co1 (Co2 / Co1) is 0 to 0.5.

[0041] Figure 1 It is a schematic cross-sectional view of the pressed powder material of this embodiment. The first magnetic metal particle is expected to have a magnetic metal phase containing Fe, Co and Si. The following is a detailed description of the situation. The Co content Co1 in the magnetic metal phase is preferably 5 atomic% to 80 atomic%, more preferably 7 atomic% to 40 atomic%, more preferably 10 atomic% to 30 atomic%, and further preferably 10 atomic% to 20 atomic%. In this way, high saturation magnetization can be achieved, preferably. In addition, the amount of Si is preferably 0.001 atomic% to 30 atomic%, more preferably 1 atomic% to 25 atomic%, and more preferably 4 atomic% to 15 atomic% relative to the entire magnetic metal phase. As a result, since the magnetocrystalline anisotropy becomes moderate in size and the coercive force is also easily reduced, it is easy to achieve low hysteresis loss and high magnetic permeability. Figure 1 A compressed powder material 100 , first magnetic metal particles 1 , and second magnetic metal particles are shown.

[0042] The second magnetic metal particle desirably has a magnetic metal phase containing Fe. The Co content (Co2) in the magnetic metal phase is preferably 0 to 2.5 atomic%, more preferably 0 to 1 atomic%. Furthermore, the amount of Si relative to the entire magnetic metal phase is preferably 0 to 30 atomic%, more preferably 0 to 10 atomic%.

[0043] The ratio of Co2 to Co1 (Co2 / Co1) is preferably 0 to 0.5. It is more preferably 0 to 0.25, and even more preferably 0 to 0.1. In order to achieve high saturation magnetization in the powder material, it is effective to increase the density of the powder material. As a method of increasing the density of the powder material, there is a method of densification by sintering. However, when the powder material is densified by sintering, the iron loss, especially the eddy current loss, will increase significantly. It can be said that the smaller the cross-sectional area of the magnetic body perpendicular to the applied magnetic field, the easier it is to reduce the eddy current loss. It is believed that the eddy current loss increases because the particles are combined and coarsened by sintering. In order to take into account both high saturation magnetization and low loss (especially low eddy current loss), it is necessary to satisfy the above-mentioned opposite characteristics at the same time. Therefore, in the present invention, a structure is prepared having at least two kinds of magnetic metal particles with different Co contents. The first magnetic metal particles with a high Co content are sintered at a higher temperature than the second magnetic metal particles with a low Co content. Therefore, by selecting an appropriate sintering temperature, it is possible to achieve a state in which sintering progresses in the second magnetic metal particles but not in the first magnetic metal particles. Furthermore, the first magnetic metal particles inhibit the sintering of the second magnetic metal particles, thereby suppressing excessive coarsening of the second magnetic metal particles. This allows for both densification of the pressed powder material and suppression of coarsening of the magnetic metal particles, achieving both high saturation magnetization and low loss.

[0044] The iron loss of the pressed powder material can be measured, for example, using a BH analyzer. Eddy current loss can be calculated, for example, from the frequency dependence of the iron loss. For example, the iron loss is measured at multiple frequencies, and the measured values are plotted with frequency as the horizontal axis and iron loss as the vertical axis. A linear approximation is performed using the least squares method. The value of the vertical axis slice at this time is assumed to be the hysteresis loss. The hysteresis loss is subtracted from the iron loss at each frequency to evaluate the eddy current loss.

[0045] Detection of elements contained in particles and measurement of their atomic concentrations can be performed, for example, using energy dispersive X-ray spectroscopy (EDX) or wavelength dispersive X-ray fluorescence spectroscopy (WDX). Furthermore, identification of substances contained in particles and the like can be performed, for example, using X-ray diffraction (XRD).

[0046] In addition, in the present embodiment, the average value of the ratio of the major diameter to the minor diameter is greater than 2 in the case of the first magnetic metal particles and greater than 1 in the case of the second magnetic metal particles, the second magnetic metal particles are present between the particles of the first magnetic metal particles, and the average value of the major diameter of the second magnetic metal particles is the same as or longer than the average value of the major diameter of the first magnetic metal particles. Here, the ratio of the major diameter to the minor diameter (major diameter / minor diameter) is the aspect ratio. As described above, in order to take into account both the high saturation magnetization and low loss of the pressed powder material, it is effective to densify the pressed powder material and suppress the coarsening of the magnetic metal particles. By making the particle shape of this embodiment, when the densification of the second magnetic metal particles by sintering is carried out, it is possible to effectively suppress the coarsening of the second magnetic metal particles brought about by the first magnetic metal particles, and take into account both high saturation magnetization and low loss. In addition, a large ratio of the major diameter to the minor diameter is effective for reducing eddy current loss. Furthermore, by adopting the particle shape of this embodiment, the second magnetic metal particles can also function as a binder with respect to the first magnetic metal particles, thereby obtaining high mechanical properties.

[0047] The average major diameter of the first magnetic metal particles is preferably 1 μm to 500 μm. It is more preferably 5 μm to 400 μm, and even more preferably 10 μm to 300 μm. If the major diameter is too short, the coercive force increases with powder refinement, leading to increased hysteresis losses. If the major diameter is too long, current pulses that cause eddy current losses are more likely to occur, increasing eddy current losses. The average ratio of the major diameter to the minor diameter is preferably 2 to 100.

[0048] The average major diameter of the second magnetic metal particles is preferably 1 μm to 800 μm. It is more preferably 5 μm to 700 μm, even more preferably 10 μm to 600 μm, and even more preferably 50 μm to 500 μm. If the major diameter is too short, sintering will not proceed sufficiently, and saturation magnetization will decrease. If the major diameter is too long, current pulses that cause eddy current loss are more likely to form, and eddy current loss will increase. The average ratio of the major diameter to the minor diameter is preferably 1 to 50.

[0049] In addition, for multiple second magnetic metal particles, when the value of the major diameter and the ratio of the major diameter to the minor diameter are plotted and linear approximation is performed, the slope (α) is preferably 0.005 / μm to 0.07 / μm. In other words, the vertical axis is the ratio of the major diameter to the minor diameter (major diameter / minor diameter) of a specific second magnetic metal particle, and the horizontal axis is the major diameter of the second magnetic metal particle, in μm, and the graph is plotted. The slope (α) is preferably 0.005 / μm to 0.07 / μm. By making the slope (α) within this range, densification and coarsening can be effectively achieved.

[0050] The existence form of the magnetic metal particles can be confirmed, for example, by observing the cross-section of the compressed powder material. The cross-section of the compressed powder material can be obtained by shearing, breaking, and grinding the compressed powder material. When the pressing direction of the compressed powder material can be identified, it is expected that the cross-section parallel to the pressing direction will be observed. In addition, it is expected that the cross-section near the center of the compressed powder material will be observed. Cross-section observation can be performed using a transmission electron microscope (TEM: Transmission Electron Microscopy) or a scanning electron microscope (SEM: Scanning Electron Microscopy) or an optical microscope, etc. The average value of the major axis and minor axis of the magnetic metal particles can be obtained from the above-mentioned cross-section observation image. Figure 2 It is a schematic diagram for explaining the method of calculating the major diameter and minor diameter of the magnetic metal particles in the pressed powder material of the first embodiment. For example, the first magnetic metal particles and the second magnetic metal particles are identified by EDX analysis. Next, an arbitrary magnetic metal particle is selected and the rectangle with the minimum area inscribed in the magnetic metal particle is calculated. The length of the long side of the obtained rectangle is defined as the major diameter of the selected magnetic metal particle, and the length of the short side of the obtained rectangle is defined as the minor diameter of the selected magnetic metal particle. This operation is performed on a plurality of first and second magnetic metal particles to obtain their respective average values, thereby obtaining the average values of the major diameter and minor diameter of the first and second magnetic metal particles. The number of selected magnetic metal particles is expected to be more than 10 for the first and second particles, respectively. When a sufficient number of particles is not observed in one observation section, it is expected that the operation is performed on a plurality of observation sections to obtain the average value.

[0051] The pressed powder material preferably has a high saturation magnetization, preferably 1 T or higher, more preferably 1.5 T or higher, even more preferably 1.8 T or higher, and even more preferably 2.0 T or higher. This suppresses magnetic saturation and allows the system to fully utilize its magnetic properties, making it preferable. The saturation magnetization of the pressed powder material can be evaluated using a vibrating sample magnetometer (VSM) or the like.

[0052] The density of the compact of the powder material is preferably 6 g / cm 3 The reason is that the density is less than 6g / cm 3 , the saturation magnetization of the pressed powder material cannot be obtained.

[0053] Next, an example of a method for producing the compressed powder material according to the first embodiment will be described.

[0054] The compacted powder material of the first embodiment can be produced by preparing first and second magnetic metal particle powders, compacting the mixed powders, and then subjecting the mixed powders to heat treatment.

[0055] The following describes methods for producing the first and second magnetic metal particle powders. Raw materials are weighed to achieve the desired composition ratio and then melted to produce an alloy. The melting method can also be high-frequency melting or arc melting. The resulting alloy can also be heat-treated for homogenization. The resulting alloy can be pulverized to produce magnetic metal powder. A ball mill, jet mill, jaw crusher, or the like can be used for pulverization. Alternatively, the alloy can be formed into a ribbon using a liquid quenching device. Liquid quenching can be performed using either a single-roll or double-roll method. Forming the alloy into a ribbon facilitates pulverization, which is preferred because it reduces deformation of the powder during the pulverization process and suppresses an increase in coercive force. The ribbon can also be heat-treated at a temperature of 300°C to 1200°C before pulverization. This further improves pulverizability. The ribbon can be pulverized using a shredder, mixer, ball mill, jet mill, or the like. Alternatively, an atomization method can be used to produce magnetic metal particle powder. Gas atomization or water atomization can be used for atomization. Alternatively, carbonyl iron powder produced by thermal decomposition of carbonyl iron or reduced iron powder obtained by reducing iron oxide may be used. The obtained powder may be classified using a mesh or sieve.

[0056] The first and second magnetic metal particle powders are mixed. The mixing ratio is controlled so that the proportion of the second magnetic metal particle powder relative to the total amount of the first and second magnetic metal particle powders is greater than 10% and less than 90%. If the proportion of the second magnetic metal particle powder is too small, the densification effect on the pressed powder material is reduced, and the saturation magnetization is reduced. If the proportion is too large, the second magnetic metal particles coarsen, increasing eddy current loss. The proportion is more preferably 15% to 70%, and even more preferably 20% to 60%.

[0057] The mixed powder is molded. Compression molding or injection molding can be used. A small amount of binder can also be mixed during molding. The binder is preferably a resin or an oxide with a eutectic system. The resin can be, for example, 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 nitro-butadiene rubber, a styrene-butadiene rubber, a silicone resin, other synthetic rubbers, natural rubber, an epoxy resin, a phenolic resin, an allyl resin, a polybenzimidazole resin, an amide resin, a polyimide resin, a polyamide-imide resin, or a copolymer thereof. For example, an oxide having a eutectic system is used, which contains at least two third elements selected from 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). It is particularly preferred to contain a eutectic system containing at least two elements selected from B, Bi, Si, Zn, and Pb. Molding can be performed under the application of a magnetic field. In this way, the orientation of the magnetic metal particle powder can be improved. In addition, it is preferred to pressurize the magnetic metal particle powder at 1000 kgf / cm 2 Pressurizing at a pressure above 5000 kgf / cm is effective for densification of the pressed powder material. More preferably, 5000 kgf / cm 2 More preferably, 10000 kgf / cm 2 above.

[0058] The molded body is subjected to heat treatment. The heat treatment temperature is preferably 500°C to 1200°C. When the temperature is too low, the effect of densification of the pressed powder material is small and the saturation magnetization is reduced. When the temperature is too high, the coarsening of the magnetic metal particles proceeds and the eddy current loss increases. It is preferably 600°C to 1100°C, and more preferably 700°C to 1000°C. The holding time of the heat treatment is preferably 1 minute to 200 hours. When the holding time is too short, density unevenness is likely to occur inside the pressed powder material. When the holding time is too long, productivity is significantly reduced. The heat treatment atmosphere can be selected from hydrogen atmosphere, argon atmosphere, nitrogen atmosphere, air, a mixed atmosphere of hydrogen and argon, etc., vacuum, etc. In addition, the heat treatment can be performed under the application of a magnetic field. In this way, the orientation of the magnetic metal particle powder can be improved.

[0059] Alternatively, the molding process and the heat treatment process may be performed simultaneously using hot pressing or hot isostatic pressing, and the resulting molded body may be further heat treated. Densification may be performed more effectively by selecting an appropriate method based on the material composition or shape.

[0060] According to this embodiment, a compressed powder material having excellent characteristics such as high saturation magnetization, low magnetic loss, and high mechanical characteristics can be provided.

[0061] (Second embodiment)

[0062] The present embodiment differs from the first embodiment in that at least a portion of the surface of the multiple magnetic metal particles contained in the pressed powder material is covered with a covering layer having a thickness of 0.1 nm to 1 μm and containing at least one second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N) and fluorine (F).

[0063] Note that descriptions of contents overlapping with those of the first embodiment are omitted.

[0064] Figure 3A -B is a schematic diagram of the magnetic metal particle according to the second embodiment, showing the covering layer 3 .

[0065] The covering layer more preferably comprises at least one non-magnetic 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 further comprises at least one second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N), and fluorine (F). As the non-magnetic metal, Al and Si are particularly preferred from the viewpoint of thermal stability. In the case where the magnetic metal particles comprise at least one non-magnetic 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 covering layer more preferably comprises at least one non-magnetic metal that is the same as the non-magnetic metal that is one of the constituents of the magnetic metal particles. Among oxygen (O), carbon (C), nitrogen (N) and fluorine (F), oxygen (O) is preferably included, preferably an oxide or a composite oxide. The above is based on the ease of formation of the covering layer, oxidation resistance, and thermal stability. Through the above content, the adhesion between the magnetic metal particles and the covering layer can be improved, and the thermal stability and oxidation resistance of the pressed powder material can be improved. The covering layer can not only improve the thermal stability and oxidation resistance, but also improve the electrical resistance of the pressed powder material. By increasing the resistance, the eddy current loss can be suppressed and the frequency characteristics of the magnetic permeability can be improved. Therefore, the covering layer 14 is preferably electrically high-resistance, for example, preferably has a resistance value of 1 mΩ·cm or more.

[0066] In addition, the covering layer preferably contains at least one magnetic metal selected from iron, cobalt, and a compound of iron and cobalt, which is one of the constituent components of the magnetic metal particles, and contains a second element selected from at least one of oxygen (O), carbon (C), nitrogen (N), phosphorus (P) and fluorine (F).

[0067] The thickness of the covering layer is preferably as thick as possible from the perspectives of thermal stability, oxidation resistance, and electrical resistance. However, excessively thick covering layers reduce saturation magnetization and, consequently, magnetic permeability, which is not preferred. The preferred covering layer thickness is 0.1 nm to 1 μm, more preferably 0.1 nm to 100 nm.

[0068] The coating layer is preferably in the form of a film, but may also be in the form of microparticles. In the case of microparticles, the average particle size is preferably 0.1 nm to 1 μm, more preferably 0.1 nm to 100 nm. Furthermore, a mixture of film and microparticle forms is also possible.

[0069] As described above, according to the present embodiment, a compressed powder material having excellent characteristics such as high magnetic permeability, low loss, excellent mechanical characteristics, and high thermal stability can be provided.

[0070] (Third embodiment)

[0071] The system and apparatus of this embodiment include the compressed powder material of the first or second embodiment. Therefore, any overlap with the first or second embodiment will be omitted. Components containing the compressed powder material included in the system and apparatus include, for example, various rotating electrical machines such as motors and generators (e.g., motors and generators), cores for transformers, inductors, converters, choke coils, filters, and magnetic wedges for rotating electrical machines (magnetic wedges). Figure 4 This is a schematic diagram of the motor system of the third embodiment. The motor system is an example of a rotating motor system. The motor system is a system including a control system for controlling the speed and power (output power) of the motor. As a method of controlling the speed of the motor, there are control methods based on control using a bridge servo circuit, proportional current control, voltage comparison control, frequency synchronization control, phase-locked loop (PLL) control, etc. As an example, regarding the control method using PLL in Figure 4As shown in . A motor system that uses PLL to control the rotation speed of a motor comprises a motor, a rotary encoder that converts the mechanical displacement of the motor's rotation into an electrical signal to detect the rotation speed of the motor, a phase comparator that compares the rotation speed of the motor given by a certain command with the rotation speed of the motor detected by the rotary encoder and outputs the speed difference between them, and a controller that controls the motor in a manner that reduces the speed difference. On the other hand, as a method of controlling the power of the motor, there are control methods that use pulse width modulation (PWM, Pulse Width Modulation) control, pulse voltage amplitude waveform (PAM, Pulse Amplitude Modulation) control, vector control, pulse control, bipolar drive, extinction pulse level control, resistance control, and the like. In addition, as other control methods, there are control methods such as micro-step drive control, multi-phase drive control, inverter control, and switch control. As an example, regarding the control method using an inverter, in Figure 4 A motor system that controls the power of a motor using an inverter includes an AC power supply, a rectifier that converts the output of the AC power supply into a DC current, an inverter circuit that converts the DC current into an AC current of an arbitrary frequency, and a motor controlled by the AC current.

[0072] Figure 5 A schematic diagram of an electric motor according to a third embodiment. Electric motor 200 is an example of a rotating electrical machine. Electric motor 200 includes a first stator and a second rotor. While the figure shows an inner rotor type in which the rotor is positioned inside the stator, an outer rotor type in which the rotor is positioned outside the stator is also possible.

[0073] Figure 6 This is a schematic diagram of a motor core (stator) according to a third embodiment. Figure 7 This is a schematic diagram of a motor core (rotor) according to the third embodiment. The motor core 300 (motor core) corresponds to the stator and rotor cores. This point will be described below. Figure 6 This is a schematic diagram of the first stator. The first stator has a core and a winding. The winding is wound around a portion of a protrusion provided on the inner side of the core. The compressed powder material of the first and second embodiments can be placed inside the core. Figure 7 This is a schematic diagram of the first rotor. The first rotor has a core and a winding. The winding is wound around a portion of a protrusion provided on the outside of the core. The compressed powder material of the first or second embodiment can be placed within the core.

[0074] It should be noted that Figure 6 、 Figure 7This diagram shows an example of an electric motor, and the application of the compressed powder material is not limited to this. As a core for easily conducting magnetic flux, it can be applied to all kinds of electric motors.

[0075] Figure 8 This is a schematic diagram of a transformer / converter according to the third embodiment. Figure 9 It is a schematic diagram of an inductor (ring-shaped inductor, rod-shaped inductor) according to the third embodiment. Figure 10 These are schematic diagrams of inductors (chip inductors and planar inductors) according to the third embodiment. These diagrams are provided as examples. Similar to the motor core, pressed powder materials can be used in transformers / converters 400 and inductors 500 to facilitate magnetic flux conduction or utilize high magnetic permeability.

[0076] Figure 11 This is a schematic diagram of a generator 600 according to the third embodiment. The generator 600 is an example of a rotating electrical machine. The generator 600 includes either a second stator 530 using the compressed powder material of the first or second embodiment as a core, or a second rotor 540 using the compressed powder material of the first or second embodiment as a core, or both. In the figure, the second rotor 540 is arranged on the inner side of the second stator 530, but may also be arranged on the outer side. The second rotor 540 is connected to a turbine 510 provided at one end of the generator 600 via a shaft 520. The turbine 510 is rotated, for example, by a fluid supplied from an external source not shown in the figure. It should be noted that, instead of a turbine that is rotated by a fluid, the shaft may be rotated by dynamic rotation such as by transmitting regenerative energy of a vehicle. Various well-known structures may be adopted for the second stator 530 and the second rotor 540.

[0077] The shaft contacts a commutator (not shown) located on the opposite side of the second rotor from the turbine. The electromotive force generated by the rotation of the second rotor is boosted to the system voltage via a phase-separating busbar (not shown) and a main transformer (not shown) as power for the generator, and then transmitted. It should be noted that the second rotor is charged due to static electricity from the turbine or shaft current associated with power generation. Therefore, the generator is equipped with brushes to discharge the charge in the second rotor.

[0078] Furthermore, the rotating electrical machine of this embodiment can be preferably used in a railway vehicle, for example, as a motor 200 for driving a railway vehicle or as a generator 600 for generating electricity for driving a railway vehicle.

[0079] To be suitable for use in these systems and equipment, the pressed powder material can undergo various processing. For example, in the case of a sintered body, it can be subjected to mechanical processing such as grinding or cutting, while in the case of a powder, it can be mixed with a resin such as epoxy resin or polybutadiene. Surface treatment can also be applied as needed. Furthermore, winding processing can be applied as needed.

[0080] According to the system and device of the present embodiment, it is possible to realize a motor system, a motor, a transformer, an inverter, an inductor, and a generator having excellent characteristics (high efficiency and low loss).

[0081] (Example)

[0082] Examples 1 to 11 are compared with the comparative examples and described in more detail below. Table 1 shows the composition of the first and second magnetic metal particles, the ratio of Co2 to Co1 (Co2 / Co1), the average major diameter of the first and second magnetic metal particles, the average major diameter to minor diameter ratio of the first and second magnetic metal particles, the slope (α) of the linear approximation of the major diameter and major diameter to minor diameter ratio of the second magnetic metal particles, saturation magnetization, and eddy current loss for the compressed powder materials obtained by the following examples and comparative examples. Regarding the eddy current loss, using Comparative Example 1 as a reference, a reduction of 10% to 50% relative to the reference was marked as 0, a reduction of 50% or more was marked as ◎, and a reduction of less than 10% or no reduction was marked as ×.

[0083] (Example 1)

[0084] First, the raw materials are weighed in such a manner as to achieve the composition shown in Table 1, and an alloy is prepared by high-frequency melting. A strip is made from the obtained alloy using a single-roll quenching device. Then, the obtained strip is heat-treated at 500°C in an Ar atmosphere. Next, the strip is crushed using a mixer device and classified using a sieve with an opening diameter of 75 μm to obtain a first magnetic metal particle powder. Next, iron powder is prepared as the second magnetic metal particle powder, and the first magnetic metal particle powder and the second magnetic metal particle powder are mixed in such a manner that the weight ratio reaches 50:50. Using a metal mold, the strip is crushed at 12000 kgf / cm 2 The mixed powder was compacted under a pressure of . The resulting compact was heat treated at 900°C for 5 hours in a mixed atmosphere of H2 and Ar to obtain a pressed powder material. The saturation magnetization of the resulting pressed powder material was evaluated using VSM, the iron loss was measured using a BH analyzer, the eddy current loss was evaluated from the frequency dependence of the iron loss, and the average value of the major axis to minor axis ratio and the value of α were evaluated by cross-sectional SEM observation.

[0085] (Examples 2 to 7)

[0086] First, the raw materials are weighed in such a manner as to achieve the composition shown in Table 1, and an alloy is prepared by high-frequency melting. A strip is made from the obtained alloy using a single-roll quenching device. Then, the obtained strip is heat-treated at 500°C in an Ar atmosphere. Next, the strip is crushed using a mixer device and classified using a sieve with an opening diameter of 75 μm to obtain a first magnetic metal particle powder. Next, iron powder is prepared as the second magnetic metal particle powder, and the first magnetic metal particle powder and the second magnetic metal particle powder are mixed in such a manner that the weight ratio reaches 70:30. Using a metal mold, the strip is crushed at 12000 kgf / cm 2 The mixed powder was compacted at a pressure of . The resulting compact was heat treated at 1000° C. for 3 hours in a mixed atmosphere of H 2 and Ar to obtain a pressed powder material. The obtained pressed powder material was evaluated using the same method as in Example 1.

[0087] (Examples 8-9)

[0088] First, the raw materials were weighed so as to achieve the composition shown in Table 1, and an alloy was prepared by high-frequency melting. A single-roll quenching device was used to produce a belt from the obtained alloy. Then, the obtained belt was heat-treated at 500°C in an Ar atmosphere. Then, the belt was crushed using a mixer and classified using a sieve with an opening diameter of 75μm to obtain a first magnetic metal particle powder. Then, the raw materials were weighed so as to achieve the composition shown in Table 1, and an alloy was prepared by high-frequency melting. A single-roll quenching device was used to produce a belt from the obtained alloy. Then, the obtained belt was heat-treated at 500°C in an H2 atmosphere. Then, the belt was crushed using a mixer and classified using a sieve with an opening diameter of 75μm to obtain a second magnetic metal particle powder. The first magnetic metal particle powder and the second magnetic metal particle powder were mixed in a weight ratio of 60:40. Using a metal mold, 10000kgf / cm 2 The mixed powder was compacted at a pressure of . The resulting compact was heat treated at 900° C. for 10 hours in a mixed atmosphere of H 2 and Ar to obtain a pressed powder material. The obtained pressed powder material was evaluated using the same method as in Example 1.

[0089] (Example 10)

[0090] The mixed powder of the first magnetic metal particle powder and the second magnetic metal particle powder prepared by the same method as in Example 1 was subjected to a coating treatment with silicon dioxide by hydrolysis of tetraethoxysilane (TEOS). 2The coated powder was compacted at a pressure of . The resulting compact was heat treated at 900°C for 5 hours in a mixed atmosphere of H2 and Ar to obtain a pressed powder material. The obtained pressed powder material was evaluated using the same method as in Example 1.

[0091] (Example 11)

[0092] A phosphoric acid solution was added to the mixed powder of the first magnetic metal particle powder and the second magnetic metal particle powder prepared by the same method as in Example 1 and heat-treated at 200°C in the atmosphere. The heat-treated powder was coated with silicon dioxide using TEOS. A metal mold was used to heat the powder at 12000 kgf / cm 2 The coated powder was compacted at a pressure of . The resulting compact was heat treated at 900°C for 4 hours in a mixed atmosphere of H2 and Ar to obtain a pressed powder material. The obtained pressed powder material was evaluated using the same method as in Example 1.

[0093] (Comparative Example 1)

[0094] First, the raw materials are weighed in such a manner as to achieve the composition shown in Table 1, and an alloy is prepared by high-frequency melting. A strip is prepared from the obtained alloy using a single-roll quenching device. Then, the obtained strip is heat-treated at 500°C in an Ar atmosphere. Next, the strip is crushed using a mixer device and classified using a sieve with an opening diameter of 75 μm to obtain a first magnetic metal particle powder. Next, the second magnetic metal particle powder is prepared using the same method as the first magnetic metal particle powder. The first magnetic metal particle powder and the second magnetic metal particle powder are mixed in such a manner that the weight ratio reaches 50:50. Using a metal mold, the strip is crushed at 12000 kgf / cm 2 The mixed powder was compacted at a pressure of . The resulting compact was heat treated at 1000° C. for 5 hours in a mixed atmosphere of H 2 and Ar to obtain a pressed powder material. The obtained pressed powder material was evaluated using the same method as in Example 1.

[0095] (Comparative Example 2)

[0096] First, the raw materials are weighed in such a manner as to achieve the composition shown in Table 1, and an alloy is prepared by high-frequency melting. A strip is prepared from the obtained alloy using a single-roll quenching device. Then, the obtained strip is heat-treated at 500°C in an Ar atmosphere. Next, the strip is crushed using a mixer device and classified using a sieve with an opening diameter of 75 μm to obtain a first magnetic metal particle powder. Next, the second magnetic metal particle powder is prepared using the same method as the first magnetic metal particle powder. The first magnetic metal particle powder and the second magnetic metal particle powder are mixed in such a manner that the weight ratio reaches 50:50. Using a metal mold, the strip is crushed at 12000 kgf / cm 2 The mixed powder was compacted at a pressure of . The resulting compact was heat treated at 1250° C. for 5 hours in a mixed atmosphere of H 2 and Ar to obtain a pressed powder material. The obtained pressed powder material was evaluated using the same method as in Example 1.

[0097] (Comparative Example 3)

[0098] First, the raw materials are weighed in such a manner as to achieve the composition shown in Table 1, and an alloy is prepared by high-frequency melting. A strip is made from the obtained alloy using a single-roll quenching device. Then, the obtained strip is heat-treated at 500°C in an Ar atmosphere. Next, the strip is crushed using a mixer device and classified using a sieve with an opening diameter of 75 μm to obtain a first magnetic metal particle powder. Next, iron powder is prepared as the second magnetic metal particle powder, and the first magnetic metal particle powder and the second magnetic metal particle powder are mixed in such a manner that the weight ratio reaches 20:80. Using a metal mold, the strip is crushed at 12000 kgf / cm 2 The mixed powder was compacted at a pressure of . The resulting compact was heat treated at 1000° C. for 5 hours in a mixed atmosphere of H 2 and Ar to obtain a pressed powder material. The obtained pressed powder material was evaluated using the same method as in Example 1.

[0099] (Comparative Example 4)

[0100] First, the raw materials are weighed in such a manner as to achieve the composition shown in Table 1, and an alloy is prepared by high-frequency melting. A strip is made from the obtained alloy using a single-roll quenching device. Then, the obtained strip is heat-treated at 500°C in an Ar atmosphere. Next, the strip is crushed using a mixer device and classified using a sieve with an opening diameter of 75 μm to obtain a first magnetic metal particle powder. Next, iron powder is prepared as the second magnetic metal particle powder, and the first magnetic metal particle powder and the second magnetic metal particle powder are mixed in such a manner that the weight ratio reaches 90:10. Using a metal mold, the strip is crushed at 12000 kgf / cm 2The mixed powder was compacted under a pressure of . The obtained compact was heat-treated at 1000° C. for 5 hours in a mixed atmosphere of H 2 and Ar to obtain a pressed powder material.

[0101] The obtained compressed powder material was evaluated by the same method as in Example 1.

[0102]

[0103] As shown in Table 1, the Co2 to Co1 ratio (Co2 / Co1) of the compressed powder materials of Examples 1 to 11 was 0 to 0.5, the average major axis to minor axis ratio was 2 or greater for the first magnetic metal particles, and 1 or greater for the second magnetic metal particles. Furthermore, the average major axis of the second magnetic metal particles was equal to or greater than the average major axis of the first magnetic metal particles. However, the values of the comparative examples were not within these ranges.

[0104] The compressed powder materials of Examples 1 to 11 achieved a significant effect of reducing eddy current loss while maintaining high saturation magnetization, compared with the compressed powder material of Comparative Example.

[0105] While several embodiments and examples of the present invention have been described, these embodiments and examples are provided as examples and are not intended to limit the scope of the invention. These novel embodiments may be implemented in various other forms and may be omitted, replaced, or modified without departing from the spirit of the invention. These embodiments and their variations are intended to be within the scope and spirit of the invention and are also intended to be within the scope of the invention as set forth in the claims.

[0106] It should be noted that the above-mentioned embodiments are summarized in the following technical proposals.

[0107] Technical Case 1

[0108] A pressed powder material comprising first magnetic metal particles having a magnetic metal phase containing Fe and Co and second magnetic metal particles having a magnetic metal phase containing Fe, wherein when the Co amounts of the first and second magnetic metal particles relative to the total amount of Fe and Co are Co1 and Co2, respectively, the ratio of Co2 to Co1 (Co2 / Co1) is 0 to 0.5, the average value of the ratio of the major axis to the minor axis is 2 or greater in the case of the first magnetic metal particles and is 1 or greater in the case of the second magnetic metal particles, the second magnetic metal particles are present between the particles of the first magnetic metal particles, and the average value of the major axis of the second magnetic metal particles is equal to or longer than the average value of the major axis of the first magnetic metal particles.

[0109] Technical Case 2

[0110] The compressed powder material described in Technical Case 1, wherein the average length of the first magnetic metal particles is 10 μm to 300 μm, the average ratio of the major axis to the minor axis is 2 to 100 or less, and the average length of the second magnetic metal particles is 50 μm to 500 μm, and the average ratio of the major axis to the minor axis is 1 to 50.

[0111] Technical Case 3

[0112] In the compressed powder material according to claim 1 or 2, the slope of a linear approximation of the relationship between the major axis value and the major axis to minor axis ratio of the second magnetic metal particles is 0.005 / μm to 0.07 / μm.

[0113] Technical Case 4

[0114] The compressed powder material according to any one of claims 1 to 3, wherein the density of the compact is 6 g / cm 3 above.

[0115] Technical Case 5

[0116] A rotating electrical machine comprising the compressed powder material according to any one of claims 1 to 4.

[0117] Technical Case 6

[0118] A rotating electrical machine includes a core including the compressed powder material according to any one of claims 1 to 4.

Claims

1. A powder material comprising a first magnetic metal particle having a magnetic metal phase containing Fe, Co, and 0.001 atomic % to 30 atomic % of Si, and a second magnetic metal particle having a magnetic metal phase containing Fe. When the Co amounts of the first and second magnetic metal particles relative to the total amount of Fe and Co are Co1 and Co2 respectively, the ratio of Co2 to Co1 (Co2 / Co1) is 0 to 0.5, the average value of the ratio of the major axis to the minor axis is greater than 2 in the case of the first magnetic metal particles and greater than 1 in the case of the second magnetic metal particles, the second magnetic metal particles exist between the particles of the first magnetic metal particles, and the average value of the major axis of the second magnetic metal particles is the same as or longer than the average value of the major axis of the first magnetic metal particles.

2. The compressed powder material according to claim 1, wherein The first magnetic metal particles have an average length of 10 μm to 300 μm and an average ratio of major axis to minor axis of 2 to 100. The second magnetic metal particles have an average length of 50 μm to 500 μm and an average ratio of major axis to minor axis of 1 to 50.

3. The compressed powder material according to claim 1, wherein The slope of a linear approximation of the relationship between the major axis value and the ratio of the major axis to the minor axis of the second magnetic metal particles is 0.005 / μm to 0.07 / μm.

4. The compressed powder material according to claim 1, wherein The density of the molded body is 6 g / cm 3 above.

5. The compressed powder material according to claim 1, wherein The Co1 is 5 atomic % to 80 atomic % and the Co2 is 0 atomic % to 2.5 atomic %. The compressed powder material according to claim 1 , wherein The first magnetic metal phase of the first magnetic metal particle further contains 0.001 atomic % to 30 atomic % of Si based on the entire first magnetic metal phase. The second magnetic metal phase of the second magnetic metal particle further contains 0 atomic % to 30 atomic % of Si based on the entire second magnetic metal phase. 7 . A rotating electrical machine comprising the compressed powder material according to claim 1 . 8 . A rotating electrical machine comprising a core comprising the compressed powder material according to claim 1 . 9 . A magnetic wedge for a rotating electrical machine, comprising the compressed powder material according to claim 1 . 10 . A core for a rotating electrical machine, comprising the compressed powder material according to claim 1 .

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