Magnetic component and magnetic powder

Abstract

This magnetic component includes a magnetic powder, wherein the magnetic powder includes a metal portion, an oxide film, and at least one specific kind of particles. The specific particles contain Cu as a main component. The specific particles are present at the interface between the metal portion and the oxide film. The specific particles have a particle size of 3 to 70 nm.

Description

Magnetic parts and magnetic powder

[0001] The present invention relates to a magnetic component comprising a magnetic powder, and to a magnetic powder used in the magnetic component.

[0002] Patent Document 1 describes a soft magnetic powder, which contains Fe ｘ Cu ａ Nb ｂ (Si １－ｙ B ｙ ) １００－ｘ－ａ－ｂ The soft magnetic powder and the powder core containing the soft magnetic powder are disclosed. The soft magnetic powder contains particles having a composition represented by the formula: ａ Si ｂ B ｃ Cu ｄ The nanocrystalline soft magnetic alloy has crystal grains at least partially present, with an average grain size of 50 nm or less, and the nanocrystalline soft magnetic alloy has Cu segregated portions at a depth of more than 2 nm from the surface of the nanocrystalline soft magnetic alloy, with Cu elements segregated in the Cu segregated portions, and a magnetic core using this nanocrystalline soft magnetic alloy. ａ Si ｂ B ｃ Cu ｄ The amorphous alloy ribbon has a Cu segregation portion on the surface side of the amorphous alloy ribbon, and Cu is segregated in the Cu segregation portion at a higher concentration than in the outermost surface portion of the amorphous alloy ribbon. The amorphous alloy ribbon is also disclosed as a magnetic core using a nanocrystalline soft magnetic alloy obtained by heat-treating the amorphous alloy ribbon to nanocrystallize it.

[0003] JP 2022-121260 A Japanese Patent No. 5429613 A Japanese Patent No. 5339192 A

[0004] Magnetic components such as magnetic cores require high DC bias characteristics and low iron loss in order to be compact and to handle large currents.

[0005] Therefore, an object of the present invention is to provide a magnetic component that satisfies the above requirements and a magnetic powder that is suitable as a material for such a magnetic component.

[0006] One aspect of the present invention provides a magnetic component comprising a magnetic powder as a first magnetic component, wherein the magnetic powder comprises a metal portion, an oxide film, and at least one specific particle, the specific particle being primarily composed of Cu, the specific particle being present at the interface between the metal portion and the oxide film, and the specific particle having a particle size of 3 to 70 nm.

[0007] Another aspect of the present invention provides a first magnetic powder comprising a metal portion, an oxide film, and at least one specific particle, wherein the specific particle is primarily composed of Cu, the specific particle is present at the interface between the metal portion and the oxide film, and the specific particle has a particle size of 3 to 70 nm.

[0008] The magnetic powder included in the magnetic component according to the present invention has the following characteristics: the magnetic powder includes a metal portion, an oxide film, and at least one specific particle; the specific particle is primarily composed of Cu; the specific particle is present at the interface between the metal portion and the oxide film; and the specific particle has a particle size of 3 to 70 nm. As a result, the magnetic component according to the present invention has improved DC bias characteristics and suppressed iron loss.

[0009] The objects of the present invention will be appreciated and its construction will be more completely understood by studying the following description of the best mode for carrying out the invention in conjunction with the accompanying drawings.

[0010] 1 is a schematic cross-sectional view showing a portion of a magnetic component according to an embodiment of the present invention. 2 is a schematic cross-sectional view showing a portion of a magnetic powder used as a material for the magnetic component of FIG. 1. 3 is a scanning transmission electron microscope (STEM) image showing a portion of the magnetic powder of Example 7. In the figure, the locations where area analysis was performed are indicated as P1, P2, P3, and P4, respectively.

[0011] While the present invention may be embodied in various forms and variations, the following detailed description of specific embodiments thereof, as illustrated in the drawings, is by way of example only and is not intended to limit the invention to the specific forms disclosed herein, but to embrace all modifications, equivalents, and alternatives within the scope of the appended claims.

[0012] 1 , a magnetic component 500 according to an embodiment of the present invention is a composite magnetic body in which magnetic powder 100 is dispersed within a hardened binder 600. That is, the magnetic component 500 includes the magnetic powder 100.

[0013] The magnetic powder 100 according to the embodiment of the present invention is an Fe-based soft magnetic alloy powder containing Fe as a main element and an amorphous phase as a main phase. The composition of the magnetic powder 100 will be described later. The magnetic powder 100 according to the present embodiment can be used directly as a material for producing various magnetic parts and dust cores.

[0014] Referring to Figure 2, magnetic powder 100 of this embodiment has an amorphous phase as the main phase and is composed of a plurality of particles 110 that are approximately spherical. However, the present invention is not limited to this, and particles 110 may have a shape other than approximately spherical. The surfaces of particles 110 of this embodiment are not coated with glass or the like. However, the present invention is not limited to this, and the surfaces of particles 110 may be coated with glass or the like. Magnetic powder 100 in which the surfaces of particles 110 are coated with glass or the like has improved insulation resistance and improved flowability compared to magnetic powder 100 in which the surfaces of particles 110 are not coated with glass or the like.

[0015] 2 , particle 110 of the present embodiment includes a metal portion 200, an oxide film 300, and at least one specific particle 400. That is, magnetic powder 100 of the present embodiment includes a metal portion 200, an oxide film 300, and at least one specific particle 400.

[0016] Referring to Figure 2, the metal portion 200 of this embodiment is mainly composed of Fe. The metal portion 200 has a crystalline phase. More specifically, the metal portion 200 has nanocrystals. These nanocrystals are generated by heat treating the magnetic powder 100 as described below. The metal portion 200 is located deeper from the surface of the particle 110 than the oxide film 300.

[0017] 2, the oxide film 300 of this embodiment is a film containing oxide as its main component. That is, the oxide film 300 is mainly composed of O. The proportion of O contained in the oxide film 300 is 35 at % or more. The oxide film 300 is located shallower from the surface of the particle 110 than the metal portion 200. The oxide film 300 forms the surface of the magnetic powder 100.

[0018] 2 , the specific particles 400 of this embodiment are primarily composed of Cu. At least one of the specific particles 400 is located at the interface between the metal portion 200 and the oxide film 300. In other words, the magnetic powder 100 includes at least one specific particle 400 located at the interface between the metal portion 200 and the oxide film 300. In the radial direction of the particle 110, one surface of the specific particle 400 is in contact with the metal portion 200, and the other surface of the specific particle 400 is in contact with the oxide film 300. The magnetic powder 100 may be configured such that at least one of the specific particles 400 is located at the interface between the metal portion 200 and the oxide film 300, and at least another of the specific particles 400 is located inside the oxide film 300. This is preferable because the magnetic powder 100 is less likely to become magnetically saturated.

[0019] Referring to FIG. 2 , the specific particles 400 of this embodiment have a particle size of 3 to 70 nm. Furthermore, if the particle size of the specific particles 400 is too small, the magnetic coupling between the particles 110 cannot be suppressed. For this reason, the specific particles 400 preferably have a particle size of 5 nm or more. Cu, which is the main component of the specific particles 400, is conductive. Therefore, if the particle size of the specific particles 400 is too large, an eddy current is more likely to flow in the specific particles 400 due to an AC magnetic field, increasing eddy current loss. For this reason, the specific particles 400 preferably have a particle size of 50 nm or less.

[0020] The concentration of Cu contained in the specific particle 400 of the present embodiment is 40 at % or more. In addition, the concentration of Cu contained in the specific particle 400 is preferably 60 at % or more in order to suppress magnetic coupling between the particles 110.

[0021] 2 , the aspect ratio of the specific particle 400 of the present embodiment is greater than 1. Furthermore, when the specific particle 400 has an elliptical cross section, the surface of the particle 110 can be efficiently made nonmagnetic, and therefore the aspect ratio of the specific particle 400 is preferably 1.4 or greater.

[0022] In the magnetic powder 100 of this embodiment, the specific particles 400 exist independently without being directly bound to one another. However, the present invention is not limited to this, and multiple specific particles 400 may be directly bound to one another to form larger particles. This is preferable because the magnetic powder 100 is less likely to become magnetically saturated.

[0023] Referring to FIG. 2 , the occupancy rate Oc of the specific particles 400 in this embodiment is 4 to 60%. Here, the occupancy rate Oc is a value obtained by the following formula (1), where Lb is the length of the interface between the metal portion 200 and the oxide film 300 when the particle 110 of the magnetic powder 100 is viewed at a predetermined cross section, and Li (i = 1 to n) is the length along the interface between the metal portion 200 and the oxide film 300 for each of n specific particles 400 located on the interface between the metal portion 200 and the oxide film 300. Formula (1): Oc = (ΣLi) / Lb*100. Note that if the occupancy rate of the specific particles 400 is too small, the magnetic coupling between the particles 110 cannot be suppressed. For this reason, the occupancy rate of the specific particles 400 is preferably 10% or more. Because Cu, the main component of the specific particles 400, is conductive, an AC magnetic field may cause eddy currents to flow in the specific particles 400. However, by locating the specific particles 400 at intervals, it is possible to ensure insulation between the specific particles 400 and suppress an increase in eddy current loss. For this reason, it is preferable that the occupancy rate of the specific particles 400 is 50% or less.

[0024] The composition range of the magnetic powder 100 according to this embodiment will be explained in more detail below.

[0025] Referring to FIG. 1, magnetic powder 100 of the present embodiment has the composition formula Fe, excluding unavoidable impurities. ａ Si ｂ B ｃ P ｄ Cu ｅ M ｆ The composition formula is Fe ａ Si ｂ B ｃ P ｄ Cu ｅ M ｆ In the formula, M is Cr and / or Nb, and 75.4 at%≦a≦86.4 at%, 0 at%≦b≦9 at%, 4 at%≦c≦13 at%, 3 at%≦d≦12 at%, 0.3 at%≦e≦1.0 at%, and 0 at%≦f≦5 at%.

[0026] In the magnetic powder 100 according to this embodiment, Fe is the main element and is an essential element responsible for magnetism. The higher the Fe content, the higher the magnetic flux density Bs and the lower the raw material cost. Furthermore, if the Fe content is below 75.4 at%, Tx1 (described below) increases and ΔT (described below) decreases. This makes heat treatment of the magnetic powder 100 difficult, resulting in a deterioration in magnetic properties after heat treatment. Furthermore, if the Fe content exceeds 86.4 at%, the amorphous nature decreases significantly, resulting in a deterioration in soft magnetic properties. In addition, since the crystallinity of the magnetic powder 100 is suppressed to improve the amorphous nature and improve the soft magnetic properties of the magnetic powder 100 after heat treatment, the Fe content is more preferably in the range of 77.9 to 84.9 at%.

[0027] In the magnetic powder 100 according to this embodiment, the Si element is responsible for forming the amorphous phase. When the magnetic powder 100 contains Si, ΔT (described later) increases, and heat treatment can be carried out stably. However, if the proportion of Si exceeds 9 at%, the amorphous-forming ability decreases, and it becomes impossible to obtain a magnetic powder 100 having an amorphous phase as the main phase. Therefore, the proportion of Si is preferably 9 at% or less.

[0028] In the magnetic powder 100 according to this embodiment, the B element is an essential element responsible for forming an amorphous phase. If the B proportion is below 4 at%, it becomes difficult to form an amorphous phase by rapid cooling when producing the magnetic powder 100, and good magnetic properties cannot be obtained. Furthermore, if the B proportion exceeds 13 at%, the melting point becomes high, which is undesirable for manufacturing, and the ability to form an amorphous phase also decreases. For this reason, the B proportion is preferably in the range of 4 to 13 at%.

[0029] In the magnetic powder 100 according to this embodiment, the P element is an essential element responsible for forming the amorphous phase. The inclusion of P in the magnetic powder 100 facilitates the formation of a fine, uniform nanocrystalline structure, resulting in good magnetic properties. Furthermore, P has a high affinity with Cu, allowing specific particles 400 to be efficiently formed near the surface of the particles 110. However, if the P ratio exceeds 12 at%, the balance with other metalloid elements becomes poor, reducing the ability to form an amorphous phase. Furthermore, if the P ratio exceeds 12 at%, the saturation magnetic flux density Bs decreases significantly. Furthermore, if the P ratio falls below 3 at%, the crystal grains tend to become large, making it impossible to obtain good magnetic properties. Therefore, the P ratio is preferably in the range of 3 to 12 at%.

[0030] In the magnetic powder 100 according to this embodiment, Cu is an essential element that contributes to the formation of a nanocrystalline phase. If the Cu content is below 0.3 at%, cluster precipitation during heat treatment is minimal, making uniform nanocrystallization difficult. Furthermore, if the Cu content exceeds 1.0 at%, the amorphous-forming ability decreases, and the occupancy of the specific particles 400 becomes too large. Therefore, the Cu content is preferably in the range of 0.3 to 1.0 at%. In particular, to improve the amorphous nature of the magnetic powder 100, enable uniform nanocrystallization, and ensure the appropriate size and occupancy of the specific particles 400, thereby improving the soft magnetic properties after heat treatment, it is more preferable that the Cu content be 0.7 at% or less.

[0031] In the magnetic powder 100 of this embodiment, the proportion of M is 0 at % or more and 5 at % or less, where M is Cr and / or Nb.

[0032] The inclusion of Cr in the magnetic powder 100 of this embodiment makes it easier for an oxide film 300 to form on the surface of the particles 110 of the magnetic powder 100, thereby improving corrosion resistance. Furthermore, the inclusion of Nb in the magnetic powder 100 of this embodiment suppresses the growth of bccFe (αFe) crystal grains during nanocrystallization, making it easier to form a fine nanocrystalline structure. However, the inclusion of Cr and Nb relatively reduces the proportion of Fe in the magnetic powder 100, thereby reducing the saturation magnetic flux density Bs of the magnetic powder 100 and the ability of the magnetic powder 100 to form an amorphous phase. Therefore, the proportion of M in the magnetic powder 100 needs to be 5 at% or less.

[0033] The magnetic powder 100 according to this embodiment is preferably one in which 3 at % or less of Fe is substituted with one or more elements selected from Co, Ni, Zn, Zr, Hf, Mo, Ta, W, Ag, Au, Pd, Na, K, Ca, Mg, Sn, Ti, V, Mn, Al, S, C, O, N, Bi, and rare earth elements. This makes it possible to easily precipitate uniform nanocrystals in the magnetic powder 100 when the magnetic powder 100 is heat-treated, and also makes it possible to keep the adverse effects of the above elements on the magnetic properties of the magnetic powder 100 within an acceptable range.

[0034] The magnetic powder 100, the magnetic component 500, and the manufacturing method thereof according to this embodiment will be described in more detail below.

[0035] The magnetic powder 100 of this embodiment can be produced by an atomization method such as water atomization or gas atomization. The magnetic powder 100 produced in this manner has an amorphous phase as its main phase and is composed of a plurality of substantially spherical particles 110. However, the present invention is not limited to this, and the magnetic powder 100 may be composed of flakes formed by pulverizing an amorphous ribbon. In other words, the particles 110 constituting the magnetic powder 100 of the present invention do not have to be substantially spherical. Even the magnetic powder 100 formed by pulverizing an amorphous ribbon in this manner can have a high saturation magnetic flux density Bs and a high relative permeability μ by having the configuration of the present invention.

[0036] In the powder production process using the atomization method, first, raw materials are prepared. Next, the raw materials are weighed to a predetermined composition and melted to produce a molten alloy. At this time, the magnetic powder 100 of this embodiment has a low melting point, so the power consumption required for melting can be reduced. Next, the molten alloy is discharged from a nozzle and broken into alloy droplets using high-pressure gas or water, thereby producing fine magnetic powder 100.

[0037] In the above-described powder production process, the gas used for fragmentation may be an inert gas such as argon or nitrogen. Furthermore, to improve the cooling rate, the alloy droplets immediately after fragmentation may be rapidly cooled by contacting them with a cooling liquid or solid, or the alloy droplets may be fragmented again to further refine them. When a liquid is used for cooling, for example, water or oil may be used. When a solid is used for cooling, for example, a rotating copper roll or a rotating aluminum plate may be used. However, the cooling liquid or solid is not limited to these, and various materials may be used.

[0038] Here, the quenching rate by the atomization method is 10 ３ K / s or more. ３ If the quenching rate is less than 10 K / s, the amount of precipitated initial crystals (mainly bccFe) increases, and accordingly, the amount of Cu precipitated in the metal part 200 also increases. ３ If the quenching rate is less than 10 K / s, the composition of the amorphous phase in the magnetic powder 100 will deviate from the desired composition, and the glass transition temperature Tg will not appear. ３ If the cooling rate is less than 10 K / s, the first crystallization starting temperature Tx1 will be shifted to the higher temperature side, or the temperature peak due to the first crystallization will be lowered. ４ K / s or more is preferred.

[0039] Furthermore, the magnetic powder 100 of the present invention preferably contains nanocrystals. Here, the magnetic powder 100 containing nanocrystals is obtained by subjecting the magnetic powder 100 to a heat treatment under predetermined heat treatment conditions, as described below, to precipitate nanocrystals of bccFe (αFe).

[0040] When magnetic powder 100 is heat-treated in a low-oxygen atmosphere primarily composed of an inert gas such as argon, it undergoes crystallization two or more times. The temperature at which crystallization first begins is called the first crystallization onset temperature (Tx1), and the temperature at which crystallization begins the second time is called the second crystallization onset temperature (Tx2). The temperature difference between the first crystallization onset temperature (Tx1) and the second crystallization onset temperature (Tx2) is called ΔT = Tx2 - Tx1. The first crystallization onset temperature (Tx1) is the exothermic peak of αFe nanocrystal precipitation, and the second crystallization onset temperature (Tx2) is the exothermic peak of compound precipitation such as FeB or FeP. These crystallization onset temperatures can be evaluated, for example, by performing thermal analysis using a differential scanning calorimetry (DSC) device at a heating rate of approximately 10°C / min.

[0041] In order to precipitate α-Fe nanocrystals in the magnetic powder 100, it is desirable to perform heat treatment at a temperature equal to or lower than the second crystallization onset temperature (Tx2) so as to suppress the precipitation of compound phases. Here, if ΔT is large, heat treatment under specified heat treatment conditions becomes easier. Therefore, it is possible to precipitate only α-Fe nanocrystals by heat treatment, thereby obtaining magnetic powder 100 with good soft magnetic properties. In other words, by adjusting the elemental composition of magnetic powder 100 so as to increase ΔT and then performing heat treatment, the α-Fe nanocrystalline structure contained in magnetic powder 100 is stabilized, and the iron loss of magnetic component 500 including magnetic powder 100 containing α-Fe nanocrystals is also reduced.

[0042] To produce magnetic powder 100 containing nanocrystals, magnetic powder 100 produced by the above-mentioned powder production process is heat-treated as described above to precipitate α-Fe nanocrystals in magnetic powder 100. As described above, this heat treatment must be carried out at or below the second crystallization onset temperature (Tx2) so as not to precipitate a compound phase. Furthermore, in order to form oxide films 300 on the surfaces of particles 110 of magnetic powder 100, this heat treatment is preferably carried out at a temperature of 300° C. or higher in a low-oxygen atmosphere primarily composed of an inert gas such as nitrogen or argon.

[0043] The magnetic powder 100 produced by the above-described powder production process can be used to manufacture the magnetic component 500. For example, the magnetic component 500 can be manufactured by molding the magnetic powder 100 into a predetermined shape and then subjecting it to heat treatment under predetermined heat treatment conditions. Furthermore, the magnetic component 500 can be used to manufacture magnetic components such as transformers, inductors, motors, and generators. A method for manufacturing the magnetic component 500 of this embodiment using the magnetic powder 100 will be described below.

[0044] The manufacturing method of the magnetic part 500 of this embodiment includes a step of manufacturing a mixture of the magnetic powder 100 of this embodiment and the binder 600, a step of pressurizing and molding this mixture to manufacture a molded body, and a step of heat-treating this molded body.

[0045] First, in the process of producing a mixture of magnetic powder 100 and binder 600, the magnetic powder 100 of this embodiment is mixed with binder 600 having good insulating properties, such as resin, to obtain a mixture (granulated powder). When using resin as binder 600, for example, silicone, epoxy, phenol, melamine, polyurethane, polyimide, or polyamide-imide may be used. To improve insulating properties and binding properties, materials such as phosphates, borates, chromates, oxides (silica, alumina, magnesia, etc.), and inorganic polymers (polysilane, polygermane, polystannane, polysiloxane, polysilsesquioxane, polysilazane, polyborazylene, polyphosphazene, etc.) may be used as binder 600 instead of or in addition to resin. Furthermore, multiple binders 600 may be used in combination, or a two- or more-layer coating structure may be formed using different binders 600. Since the manufacturing process of magnetic component 500 includes a heat treatment process for the molded body as described above, it is preferable to use a binder 600 with high heat resistance. The amount of binder 600 is generally preferably about 0.1 to 10 wt %, and when the insulation property and filling rate are taken into consideration, about 0.3 to 6 wt % is preferable. However, the amount of binder 600 may be appropriately determined taking into consideration the powder particle size, applied frequency, application, etc.

[0046] Next, in the process of pressure-molding the mixture to produce a molded body, the granulated powder is pressure-molded using a mold to obtain a molded body. When pressure-molding the granulated powder, a powder softer than the magnetic powder 100 according to this embodiment, such as Fe, FeSi, FeSiCr, FeSiAl, FeNi, or carbonyl iron powder, may be mixed in to improve filling properties and suppress heat generation during nanocrystallization. Alternatively, instead of or together with the soft powder, any magnetic powder 100 having a particle size different from that of the magnetic powder 100 according to this embodiment may be mixed. In this case, the amount of the mixed powder relative to the magnetic powder 100 according to this embodiment is preferably 50 wt % or less.

[0047] The compact is then subjected to a heat treatment under predetermined heat treatment conditions. This heat treatment precipitates α-Fe nanocrystals in the magnetic powder 100. This heat treatment is similar to the heat treatment for the magnetic powder 100 described above, and must be carried out at a temperature equal to or lower than the second crystallization onset temperature (Tx2). Furthermore, in order to form an oxide film 300 on the surfaces of the particles 110 of the magnetic powder 100, this heat treatment is preferably carried out at a temperature of 300° C. or higher in a low-oxygen atmosphere primarily composed of an inert gas such as nitrogen or argon.

[0048] Although the magnetic component 500 in this embodiment is manufactured using magnetic powder 100 that has not been heat-treated as a raw material, the present invention is not limited to this, and the magnetic component 500 may be manufactured using magnetic powder 100 that has been heat-treated in advance to precipitate α-Fe nanocrystals as a raw material. In this case, the magnetic component 500 can be manufactured by performing granulation and pressure molding in the same manner as in the manufacturing process of the magnetic component 500 described above.

[0049] The magnetic powder 100 of the present embodiment is used in the magnetic component 500 of the present embodiment produced as described above, regardless of the production process. Similarly, the magnetic powder 100 of the present embodiment is used in the magnetic component 500 of the present embodiment.

[0050] Hereinafter, the embodiment of the present invention will be described in more detail with reference to several examples.

[0051] (Examples 1 to 39 and Comparative Examples 1 to 10) Industrially pure iron, ferrosilicon, ferrophosphorus, ferroboron, ferrochrome, and electrolytic copper were prepared as raw materials for the magnetic powders 100 of Examples 1 to 15 and 24 to 28 and Comparative Examples 1 to 5 and 10 listed in Table 2 below. The raw materials were weighed to obtain the alloy compositions of Examples 1 to 39 and Comparative Examples 1 to 10, and melted by high-frequency melting in an argon atmosphere to produce molten alloys. The molten alloys were then quenched by water atomization to produce magnetic powders 100 with an average particle size of 3 to 15 μm. Similarly, magnetic powders 100 with an average particle size of 15 to 65 μm were produced for the magnetic powders 100 of Examples 16 to 23 and 29 to 39 and Comparative Examples 6 to 9 listed in Table 2 below.

[0052] The magnetic powder 100 produced in Example 7 was heat-treated in an electric furnace in a low-oxygen atmosphere mainly composed of inert gas at a predetermined temperature between 375°C and 475°C for a predetermined time. During this heat treatment, the oxygen concentration in the treatment atmosphere was set to be in the range of 5 to 10,000 ppm, and the oxygen concentration at the start of the temperature rise was set to be higher than the oxygen concentration after a predetermined time had passed. This heat treatment also nanocrystallized the magnetic powder 100.

[0053] A thin film sample was prepared from the heat-treated magnetic powder 100 of Example 7 by the FIB (focused ion beam) method. The prepared thin film sample was observed with a scanning transmission electron microscope (STEM). Furthermore, elemental mapping analysis and area analysis were performed on the prepared thin film sample using energy dispersive X-ray spectroscopy (STEM-EDS). The results of the STEM observation and elemental mapping analysis are shown in Figure 3. The locations where area analysis was performed (P1, P2, P3, P4) are shown in Figure 3, and the elemental analysis results for each location are shown in Table 1.

[0054]

[0055] From FIG. 3, it was confirmed that the magnetic powder 100 of Example 7 comprises a plurality of specific particles 400 composed primarily of Cu. Furthermore, from FIG. 3 and Table 1, it was confirmed that Cu was contained at a high concentration of 69.2 at% at the P1 portion of the magnetic powder 100 of Example 7. Furthermore, from FIG. 3 and Table 1, it was confirmed that the particle size of the particles at the P1 portion was approximately 16 nm. Furthermore, from FIG. 3 and Table 1, it was confirmed that O was contained at high concentrations of 67.9 at% and 60.1 at%, respectively, at the P2 and P3 portions of the magnetic powder 100 of Example 7, while Cu was hardly contained. Furthermore, from FIG. 3 and Table 1, it was confirmed that Fe was contained at a high concentration of 80.6 at% at the P4 portion of the magnetic powder 100 of Example 7, while Cu was hardly contained. From these results, it was confirmed that the magnetic powder 100 of Example 7 comprises a metal part 200 whose main component is Fe, an oxide film 300 whose main component is O, and a plurality of specific particles 400 whose main component is Cu, the specific particles 400 being present at the interface between the metal part 200 and the oxide film 300, and the particle size of the specific particles 400 being in the range of 3 to 70 nm.

[0056] Using the magnetic powder 100 before heat treatment according to Examples 1 to 39 produced by the above method, magnetic components (dust cores) 500 according to Examples 1 to 39 were produced by the following method.

[0057] First, the magnetic powder 100 manufactured in Examples 1 to 39 and the binder (silicone resin) 600 were mixed so that the ratio of binder 600 to magnetic powder 100 was 3 wt %, and the mixture was sieved using a stainless steel sieve with a mesh size of 500 μm to obtain granules. The granules were then filled into a mold and molded using a hydraulic press at a molding pressure of 490 MPa. This resulted in a cylindrical molded body with an outer diameter of 13 mm and an inner diameter of 8 mm. The molded body was then heated to a predetermined temperature between 375°C and 475°C at a heating rate of 30°C / min in a low-oxygen atmosphere primarily composed of an inert gas using an infrared heating device, and then held at the predetermined temperature for 20 minutes. The molded body was then air-cooled to room temperature to produce the magnetic components (dust cores) 500 of Examples 1 to 39. In this heat treatment, the oxygen concentration in the treatment atmosphere was set to be in the range of 5 to 10,000 ppm, and the oxygen concentration at the start of the temperature rise was set to be higher than the oxygen concentration immediately before air cooling. This heat treatment also hardens the silicone resin that is the binder 600 and nano-crystallizes the magnetic powder 100.

[0058] Furthermore, magnetic components (dust cores) according to Comparative Examples 1 to 10 were produced using the powders of Comparative Examples 1 to 10 in a manner similar to that described above.

[0059] The powder magnetic cores 500 produced in Examples 1 to 39 were cut, then processed with a cross section polisher (CP), and thin film samples were produced by the focused ion beam (FIB) method. The produced thin film samples were observed with a TEM to obtain multiple TEM images, and elemental analysis was performed using an EDX attached to the TEM. Based on these observation and analysis results, the particle size, aspect ratio, and Cu concentration of the specific particles 400 in the magnetic powder 100 constituting the powder magnetic cores 500 produced in Examples 1 to 39 were derived. Furthermore, based on each of the obtained TEM images, the length Lb of the interface between the metal part 200 and the oxide film 300 and the length Li (i = 1 to n) along the interface between the metal part 200 and the oxide film 300 for each of the n specific particles 400 located on the interface between the metal part 200 and the oxide film 300 were derived, and the occupancy Oc was calculated using the above formula (1). The average of the obtained occupancy Oc was used as the occupancy Oc of the powder cores 500 of Examples 1 to 39. In addition, using a method similar to that described above, the particle size, aspect ratio, and Cu concentration of the specific particles in the powder constituting the powder cores of Comparative Examples 1 to 10 were derived, and the occupancy Oc was calculated. These results are shown in Table 2.

[0060]

[0061] From Table 2, it can be seen that in the powder magnetic cores 500 of Examples 1 to 28, the particle size of the specific particles 400 containing Cu as the main component is in the range of 3 to 70 nm, the concentration of Cu contained in the specific particles 400 is 40 at% or more, the aspect ratio of the specific particles 400 is greater than 1, and the occupancy rate of the specific particles 400 is in the range of 4 to 60%.

[0062] Furthermore, Table 2 shows that the magnetic powders 100 of Examples 29 and 30 have 3 at% or less of Fe replaced with C, but that in the powder magnetic cores 500 of Examples 29 and 30, the particle size of the specific particles 400, which are primarily composed of Cu, is in the range of 3 to 70 nm, the concentration of Cu contained in the specific particles 400 is 40 at% or more, the aspect ratio of the specific particles 400 is greater than 1, and the occupancy rate of the specific particles 400 is in the range of 4 to 60%.

[0063] Furthermore, Table 2 shows that the magnetic powder 100 of Example 31 has 3 at% or less of Fe replaced with Co, but in the powder magnetic core 500 of Example 31, the particle size of the specific particles 400, which are primarily composed of Cu, is in the range of 3 to 70 nm, the concentration of Cu contained in the specific particles 400 is 40 at% or more, the aspect ratio of the specific particles 400 is greater than 1, and the occupancy rate of the specific particles 400 is in the range of 4 to 60%.

[0064] Furthermore, Table 2 shows that the magnetic powder 100 of Example 32 has 3 at% or less of Fe replaced with Zn, but in the powder magnetic core 500 of Example 32, the particle size of the specific particles 400, which are primarily composed of Cu, is in the range of 3 to 70 nm, the concentration of Cu contained in the specific particles 400 is 40 at% or more, the aspect ratio of the specific particles 400 is greater than 1, and the occupancy rate of the specific particles 400 is in the range of 4 to 60%.

[0065] Furthermore, Table 2 shows that the magnetic powders 100 of Examples 33 and 34 have 3 at% or less of Fe replaced with Sn, but in the powder magnetic cores 500 of Examples 33 and 34, the particle size of the specific particles 400 containing Cu as the main component is in the range of 3 to 70 nm, the concentration of Cu contained in the specific particles 400 is 40 at% or more, the aspect ratio of the specific particles 400 is greater than 1, and the occupancy rate of the specific particles 400 is in the range of 4 to 60%.

[0066] Furthermore, Table 2 shows that the magnetic powder 100 of Example 35 has 3 at% or less of Fe replaced with Ni, and that in the powder magnetic core 500 of Example 35, the particle size of the specific particles 400, which are primarily composed of Cu, is in the range of 3 to 70 nm, the concentration of Cu contained in the specific particles 400 is 40 at% or more, the aspect ratio of the specific particles 400 is greater than 1, and the occupancy rate of the specific particles 400 is in the range of 4 to 60%.

[0067] Furthermore, Table 2 shows that the magnetic powder 100 of Example 36 has 3 at% or less of Fe replaced with Mn, and that in the powder magnetic core 500 of Example 36, the particle size of the specific particles 400 containing Cu as the main component is in the range of 3 to 70 nm, the concentration of Cu contained in the specific particles 400 is 40 at% or more, the aspect ratio of the specific particles 400 is greater than 1, and the occupancy rate of the specific particles 400 is in the range of 4 to 60%.

[0068] Furthermore, Table 2 shows that the magnetic powder 100 of Example 37 has 3 at% or less of Fe replaced with Al, and that in the powder magnetic core 500 of Example 37, the particle size of the specific particles 400, which are primarily composed of Cu, is in the range of 3 to 70 nm, the concentration of Cu contained in the specific particles 400 is 40 at% or more, the aspect ratio of the specific particles 400 is greater than 1, and the occupancy rate of the specific particles 400 is in the range of 4 to 60%.

[0069] Furthermore, Table 2 shows that the magnetic powder 100 of Example 38 has 3 at% or less of Fe replaced with Ti, while the powder core 500 of Example 38 has the particle size of the specific particles 400, which are primarily composed of Cu, in the range of 3 to 70 nm, the concentration of Cu contained in the specific particles 400 is 40 at% or more, the aspect ratio of the specific particles 400 is greater than 1, and the occupancy rate of the specific particles 400 is in the range of 4 to 60%.

[0070] Furthermore, Table 2 shows that the magnetic powder 100 of Example 39 has 3 at% or less of Fe replaced with O, but in the powder core 500 of Example 39, the particle size of the specific particles 400 containing Cu as the main component is in the range of 3 to 70 nm, the concentration of Cu contained in the specific particles 400 is 40 at% or more, the aspect ratio of the specific particles 400 is greater than 1, and the occupancy rate of the specific particles 400 is in the range of 4 to 60%.

[0071] On the other hand, Table 2 shows that the powder of Comparative Example 1 has an Fe content of less than 75.4 at% and the powder of Comparative Example 2 has an Fe content of more than 86.4 at%. However, in the powder magnetic cores of Comparative Examples 1 and 2, the particle size of the specific particles is less than 3 nm, the Cu concentration in the specific particles is less than 40 at% and the occupancy rate of the specific particles is not within the range of 4 to 60%.

[0072] Furthermore, Table 2 shows that the powder of Comparative Example 3 has a Si content of more than 9 at %, but in the powder magnetic core of Comparative Example 3, the particle size of the specific particles is less than 3 nm, the Cu concentration in the specific particles is less than 40 at %, and the occupancy rate of the specific particles is not within the range of 4 to 60%.

[0073] Furthermore, Table 2 shows that the powder of Comparative Example 4 has a B content of less than 4 at %, and the powder of Comparative Example 5 has a B content of more than 13 at %, but in the powder magnetic cores of Comparative Examples 4 and 5, the particle size of the specific particles is less than 3 nm, the Cu concentration in the specific particles is less than 40 at %, and the occupancy rate of the specific particles is not within the range of 4 to 60%.

[0074] Furthermore, Table 2 shows that the powder of Comparative Example 6 has a P content of less than 3 at %, and the powder of Comparative Example 7 has a P content of more than 12 at %. However, in the powder core of Comparative Example 6, the particle size of the specific particles is less than 3 nm, and the Cu concentration in the specific particles is less than 40 at %, so the occupancy rate of the specific particles is not within the range of 4 to 60%, and in the powder core of Comparative Example 7, the particle size of the specific particles exceeds 70 nm, so the occupancy rate of the specific particles is not within the range of 4 to 60%.

[0075] Furthermore, Table 2 shows that the powder of Comparative Example 8 has a Cu content of less than 0.3 at% and the powder of Comparative Example 9 has a Cu content of more than 1.0 at%. However, in the powder core of Comparative Example 8, the particle size of the specific particles is less than 3 nm, the Cu concentration in the specific particles is less than 40 at%, and the occupancy rate of the specific particles is not within the range of 4 to 60%, and in the powder core of Comparative Example 9, the particle size of the specific particles exceeds 70 nm, and the occupancy rate of the specific particles is not within the range of 4 to 60%.

[0076] Furthermore, Table 2 shows that the powder of Comparative Example 10 has an M content exceeding 5 at%, but in the powder magnetic core of Comparative Example 10, the particle size of the specific particles is less than 3 nm, the Cu concentration in the specific particles is less than 40 at%, and the occupancy rate of the specific particles is not within the range of 4 to 60%.

[0077] For the produced powder cores 500 of Examples 1 to 15 and 24 to 28 and the powder cores of Comparative Examples 1 to 5 and 10, the DC bias characteristics at 100 kHz were measured using an LCR meter connected to a dedicated DC bias power supply, and the retention ratio R (%) was calculated. Here, the retention ratio R is a value calculated using the following formula (2), where the measured value of L (or μ) at 0 kA / m is L0 (or μ0) and the measured value of L (or μ) at 8 kA / m is Lx (or μx). Formula (2): R = Lx (or μx) / L0 (or μ0) * 100. Furthermore, for the produced powder cores 500 of Examples 1 to 15 and 24 to 28 and the powder cores of Comparative Examples 1 to 5 and 10, the iron loss Pcv (kW / m) under excitation conditions of 300 kHz and 50 mT was measured using a B-H analyzer. ３ The results are shown in Table 3.

[0078]

[0079] From Table 3, it can be seen that the powder magnetic cores 500 of Examples 1 to 15 and 24 to 28 have a retention rate R of 70% or more and an iron loss Pcv of 1250 kW / m ３ It can be seen that the following is true.

[0080] On the other hand, from Table 3, the powder magnetic cores of Comparative Examples 1 and 2, in which Fe is not within the range of 75.4 to 86.4 at%, the powder magnetic core of Comparative Example 3, in which Si exceeds 9 at%, the powder magnetic core of Comparative Example 4, in which B is less than 4 at%, the powder magnetic core of Comparative Example 5, in which B exceeds 13 at%, and the powder magnetic core of Comparative Example 10, in which M exceeds 5 at%, have a retention rate R of less than 70% and an iron loss Pcv of 1250 kW / m ３ It is clear that this exceeds

[0081] From these findings, it can be seen that the powder magnetic cores 500 of Examples 1 to 15 and 24 to 28 have improved DC bias characteristics and reduced iron loss compared to the powder magnetic cores of Comparative Examples 1 to 5 and 10.

[0082] For the powder cores 500 produced in Examples 16 to 23 and 29 to 39 and the powder cores of Comparative Examples 6 to 9, the DC bias characteristics at 100 kHz were measured using an LCR meter connected to a dedicated DC bias power supply, and the retention ratio R (%) was calculated using the above formula (2). In addition, for the powder cores 500 produced in Examples 16 to 23 and 29 to 39 and the powder cores of Comparative Examples 6 to 9, the iron loss Pcv (kW / m) under excitation conditions of 20 kHz and 100 mT was measured using a B-H analyzer. ３ The results are shown in Table 4.

[0083]

[0084] From Table 4, it can be seen that the powder magnetic cores 500 of Examples 16 to 23 and 29 to 39 have a retention rate R of 70% or more and an iron loss Pcv of 300 kW / m ３ It can be seen that the following is true.

[0085] On the other hand, as can be seen from Table 4, in the powder magnetic core of Comparative Example 6 in which P is less than 3 at %, and the powder magnetic core of Comparative Example 8 in which Cu is less than 0.3 at %, the retention rate R is less than 70%, and the iron loss Pcv is 300 kW / m ３ Furthermore, it can be seen from Table 4 that the iron loss Pcv exceeds 300 kW / m in the powder magnetic core of Comparative Example 7 in which P exceeds 12 at % and the powder magnetic core of Comparative Example 9 in which Cu exceeds 1.0 at %. ３ It is clear that this is far beyond the

[0086] From these findings, it can be seen that the powder magnetic cores 500 of Examples 16 to 23 and 29 to 39 have improved DC bias characteristics and suppressed iron loss compared to the powder magnetic cores of Comparative Examples 6 to 9.

[0087] The present invention is based on Japanese Patent Application No. 2023-103003 filed with the Japan Patent Office on June 23, 2023, the contents of which are incorporated herein by reference.

[0088] Although the best mode for carrying out the present invention has been described, it will be apparent to those skilled in the art that modifications can be made to the present invention without departing from the spirit of the present invention, and such modifications are within the scope of the present invention.

[0089] 100 Magnetic powder 110 Particle 200 Metal part 300 Oxide film 400 Specific particle 500 Magnetic part (powder core) 600 Binder Lb Length Li Length

Claims

1. A magnetic component comprising a magnetic powder, the magnetic powder comprising a metal portion, an oxide film, and at least one specific particle, the specific particle being primarily composed of Cu, the specific particle being present at the interface between the metal portion and the oxide film, and the specific particle having a particle size of 3 to 70 nm.

2. A magnetic powder comprising a metal portion, an oxide film, and at least one specific particle, the specific particle being mainly composed of Cu, the specific particle being present at the interface between the metal portion and the oxide film, and the specific particle having a particle size of 3 to 70 nm.

3. The magnetic powder according to claim 2, wherein the concentration of Cu contained in the specific particles is 40 at % or more.

4. The magnetic powder according to claim 2, wherein the aspect ratio of the specific particles is greater than 1.

5. The magnetic powder according to claim 2, wherein the occupancy rate of the specific particles is 4 to 60%.

6. The magnetic powder according to any one of claims 2 to 5, wherein the magnetic powder is composed of the composition formula Fe, excluding unavoidable impurities. ａ S ｂ B ｃ P ｄ Cu ｅ M ｆ %≦a≦86.4at%, 0at%≦b≦9at%, 4at%≦c≦13at%, 3at%≦d≦12at%, 0.3at%≦e≦1.0at%, and 0at%≦f≦5at%.

7. The magnetic powder according to claim 6, wherein 3 at % or less of the Fe is substituted with one or more elements selected from the group consisting of Co, Ni, Zn, Zr, Hf, Mo, Ta, W, Ag, Au, Pd, Na, K, Ca, Mg, Sn, Ti, V, Mn, Al, S, C, O, N, Bi and rare earth elements.

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