Iron-based soft magnetic powder

Abstract

To provide a powder from which a magnetic component having excellent magnetic properties can be obtained.SOLUTION: A soft magnetic powder comprises many particles 2. These particles 2 include particles having a diameter D2 of 50 μm or more. A ratio P2 calculated by the following formula is equal to or less than 50%: P2=(N2 / N1)*100. In the formula, N1 represents the number of particles 2 having a diameter D2 of 50 μm or more. In this formula, N2 represents the number of particles 2 having a diameter D2 of 50 μm or more. The soft magnetic powder contains: a core 8; and 20 or more projections 10 that are attached to a surface of the core 8 and whose height is 1.0 μm or more, wherein an average height of the projections 10 that have a height of 1.0 μm or more is 10 μm or more.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This specification discloses soft magnetic powder whose main component is iron. This soft magnetic powder is suitable for dust cores and other components such as reactors and inductors.

Background Art

[0002] Reactors such as motors, inverters, and converters have magnetic cores. Inductors used in circuit boards and the like also have magnetic cores. There is a demand for an increase in current in reactors and inductors. From the perspective of increasing the current, the need for magnetic materials that are less likely to cause magnetic saturation with respect to current is increasing. Furthermore, there is also a demand for miniaturization in reactors and inductors. From these perspectives, dust cores are used for reactors and inductors. A dust core can be obtained by pressure molding of metal powder. This metal powder consists of a large number of particles. Each particle has a core and an insulating film covering the core. This dust core is required to have magnetic properties that can respond sensitively to external magnetic field changes.

[0003] Some improvements regarding the magnetic properties of dust cores have been proposed. Japanese Unexamined Patent Application Publication No. 2014 - 143286 discloses soft magnetic powder containing Cr and Si. Japanese Unexamined Patent Application Publication No. 2020 - 145405 discloses soft magnetic powder having different compositions inside and on the surface of particles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a powder core is used in an alternating magnetic field, energy loss occurs. This energy loss is called "core loss." Core loss is the sum of hysteresis loss and eddy current loss. In the low-frequency range, hysteresis loss is dominant. In the high-frequency range, eddy current loss is dominant. If a powder with a thick insulating coating is used, core loss of the powder core can be suppressed. However, this powder has poor packing properties. In a powder core using this powder, saturation magnetization is insufficient. This powder core does not meet the requirements for high current applications.

[0006] The applicant's intention is to provide a powder that can yield a magnetic material with excellent magnetic properties. [Means for solving the problem]

[0007] The iron-based soft magnetic powder disclosed herein consists of numerous particles. These particles include particles with a diameter of 50 μm or more. The ratio P2, calculated by the following formula, is 50% or less. P2 = (N2 / N1) * 100 In this formula, N1 represents the number of particles with a diameter of 50 μm or more. In this formula, N2 represents the number of particles with a diameter of 50 μm or more, which include a core and 20 or more protrusions attached to the surface of the core, each with a height of 1.0 μm or more, and whose average height of the protrusions with a height of 1.0 μm or more is 10 μm or more.

[0008] Preferably, the ratio P1 calculated by the following formula is 50% or more. P1 = (N3 / N) * 100 In this formula, N represents the total number of particles, and N3 represents the number of particles with a circularity of 0.8 or higher. Preferably, this ratio P1 is 80% or less.

[0009] Preferably, the ratio P3 calculated by the following formula is 20% or less. P3 = (N4 / N1) * 100 In this formula, N1 represents the number of particles with a diameter of 50 μm or more. In this formula, N4 represents the number of particles with a diameter of 50 μm or more and having two or more pores with a diameter of 0.1 μm or more in one cross-section.

[0010] Preferably, the ratio P4 calculated by the following formula is 50% or more. P4 = (N1 / N) * 100 In this formula, N represents the total number of particles, and N1 represents the number of particles with a diameter of 50 μm or more.

[0011] Preferably, each particle has a main part and an insulating film covering all or part of the surface of the main part. The material of the main part is an iron-based alloy. Preferably, this iron-based alloy Si: 2.0 mass% or more and 10.0 mass% or less, Cr: 0.0 mass% or more and 10.0 mass% or less, Al: 0.0 mass% or more and 10.0 mass% or less, and B: 0.0 mass% or more and 10.0 mass% or less and contains the balance being Fe and inevitable impurities.

[0012] The method for manufacturing a compacted magnetic core disclosed in this specification includes the step of preparing an iron-based soft magnetic powder composed of a large number of particles, these particles containing particles with a diameter of 50 μm or more, and the ratio P2 calculated by the following formula being 50% or less. and the step of pressing the above powder. is provided. P2 = (N2 / N1) * 100 In this formula, N1 represents the number of particles with a diameter of 50 μm or more. In this formula, N2 represents the number of particles with a diameter of 50 μm or more, including 20 or more protrusions adhering to the core and its surface and having a height of 1.0 μm or more, and the average height of the protrusions having a height of 1.0 μm or more being 10 μm or more.

Advantages of the Invention

[0013] When this soft magnetic powder is pressed, the particles are pressed against the adjacent particles. Since the ratio P2 of the powder is 50% or less, particle damage due to this pressing is unlikely to occur in this powder. A magnetic member with excellent magnetic properties can be obtained from this powder.

Brief Description of the Drawings

[0014] [Figure 1] FIG. 1 is a projected view showing particles of an iron-based soft magnetic powder according to one embodiment. [Figure 2] FIG. 2 is a projected view showing the particles of FIG. 1 together with a first virtual circle and a second virtual circle. [Figure 3] FIG. 3 is a cross-sectional view showing the particles of FIG. 1. [Figure 4] FIG. 4 is an enlarged view showing a part of the particles of FIG. 1. [Figure 5] FIG. 5 is a projected view showing the particles of FIG. 1 together with a first virtual circle. [Figure 6] FIG. 6 is an enlarged view showing the pores of the particles of FIG. 3.

Mode for Carrying Out the Invention

[0015] Hereinafter, preferred embodiments will be described in detail while appropriately referring to the drawings.

[0016] The iron-based soft magnetic powder according to this embodiment is an aggregate of a large number of particles. This powder can be subjected to a pressing method to be described in detail later to obtain a molded body (for example, a powder core). In FIG. 1, a projected view of one particle 2 is shown. As is clear from FIG. 1, the particle 2 is distorted. In other words, the contour 4 of the particle 2 has irregularities. The viewing direction with respect to the particle 2 is randomly selected to obtain this projected view. The powder may include particles 2 having a shape close to a true sphere together with the distorted particles 2.

[0017] Figure 2 shows the first virtual circle 6. This first virtual circle 6 is the largest circle that can be drawn within the contour 4 of particle 2. In other words, the first virtual circle 6 is the "largest inscribed circle" as defined by the "largest inscribed circle center method". In this specification, the zone of particle 2 enclosed by the first virtual circle 6, i.e., the inside of the largest inscribed circle, is referred to as the "core 8". The zone of particle 2 outside the first virtual circle 6, i.e., the outside of the largest inscribed circle, is referred to as the "projection 10". Figure 2 shows the first projection 10a, the second projection 10b, the third projection 10c, the fourth projection 10d, the fifth projection 10e, and the sixth projection 10f. These projections 10 are attached to the core 8. In Figure 2, the symbol D1 represents the diameter of the first virtual circle 6.

[0018] Figure 2 also shows a second virtual circle 12. This second virtual circle 12 is the smallest circle that contains the outline 4 of particle 2 inside it. In Figure 2, the symbol D2 represents the diameter of the second virtual circle 12. In this specification, this diameter D2 is referred to as the "diameter of particle 2".

[0019] Figure 3 shows a cross-section of particle 2. Particle 2 has a main portion 14 and an insulating film 16. The insulating film 16 covers the surface of the main portion 14. In this embodiment, the insulating film 16 covers the entire surface of the main portion 14. Therefore, the contour 4 of particle 2 is also the contour of the insulating film 16. The insulating film 16 may cover only a part of the surface of the main portion 14. Particle 2 does not have to have an insulating film 16. From the viewpoint of suppressing core loss, it is preferable that the insulating film 16 covers the entire surface of the main portion 14. In Figure 3, reference numeral 18 represents a void (explained in detail later).

[0020] The material of the main part 14 is an iron-based alloy, which will be described in detail later. The compacted magnetic core obtained from a large number of particles 2 having this main part 14 and an insulating coating 16 exhibits excellent magnetic properties. In this specification, soft magnetic powder consisting of particles 2 whose main part 14 is an iron-based alloy is referred to as "iron-based soft magnetic powder" regardless of the material of the insulating coating 16.

[0021] [Ratio P4] In this specification, the ratio P4 is calculated using the following formula. P4 = (N1 / N) * 100 In this formula, N represents the total number of particles 2, and N1 represents the number of particles 2 with a diameter D2 of 50 μm or more. From the viewpoint of efficiency in the pressurization method for obtaining a molded body, the ratio P4 is preferably 50% or more, more preferably 60% or more, and particularly preferably 70% or more. The ratio P4 may also be 100%.

[0022] The ratio P4 is calculated using laser diffraction / scattering particle size distribution analysis. For example, Microtrac-Bell's "MT3000II particle size distribution analyzer" is used for this measurement. The particle size distribution of the powder is measured on a count basis, and the frequency of particles 2, which have a diameter of 50 μm or more, is confirmed.

[0023] [Ratio P2] Figure 4 shows a magnified view of a portion of particle 2. Figure 4 also shows the vicinity of the first projection 10a. In Figure 4, the symbol 20 represents the top of the first projection 10a. Top 20 is the point on the contour 4a of the first projection 10a that is furthest from the first virtual circle 6. The contour 4a of the first projection 10a is part of the contour 4 of particle 2. In Figure 4, the arrow H1 represents the height of the first projection 10a. Height H1 is the distance from top 20 to the first virtual circle 6. The shape of contour 4 in the vicinity of top 20 may be a curve (or a straight line) or a corner.

[0024] Figure 5 shows the height H1 of the first projection 10a, along with the heights H2 of the second projection 10b, H3 of the third projection 10c, H4 of the fourth projection 10d, H5 of the fifth projection 10e, and H6 of the sixth projection 10f. The method for determining the heights H2 of the second projection 10b, H3 of the third projection 10c, H4 of the fourth projection 10d, H5 of the fifth projection 10e, and H6 of the sixth projection 10f is the same as the method for determining the height H1 of the first projection 10a shown in Figure 4. Each height H is the distance from the top 20 to the first virtual circle 6.

[0025] In this specification, the ratio P2 is calculated using the following formula. P2 = (N2 / N1) * 100 In this formula, N1 represents the number of particles 2 whose diameter D2 is 50 μm or larger. In this formula, N2 represents the number of particles 2 that satisfy all of the following conditions 1-3. Condition 1: The diameter D2 is 50 μm or larger. Condition 2: The number Np of protrusions 10 with a height H of 1.0 μm or more is 20 or more. Condition 3: The average height Hp of the protrusions 10, whose height H is 1.0 μm or more, is 10 μm or more.

[0026] In particle 2 shown in Figure 5, the heights H1 of the first protrusion 10a, H2 of the second protrusion 10b, H3 of the third protrusion 10c, H5 of the fifth protrusion 10e, and H6 of the sixth protrusion 10f are 1.0 μm or greater. Therefore, these protrusions 10 are included in the calculation of the "number of protrusions 10 Np" and the "average height Hp of the protrusions 10". On the other hand, the height H4 of the fourth protrusion 10d is less than 1.0 μm. Therefore, the fourth protrusion 10d is not included in the calculation of the "number of protrusions 10 Np" and the "average height Hp of the protrusions 10". Fine protrusions 10 that are included in this projection and whose height has not been measured but are clearly less than 1.0 μm are also not included in the calculation of the "number of protrusions 10 Np" and the "average height Hp of the protrusions 10". Furthermore, protrusions 10 that are attached to the core 8 but do not appear in this projection are also not included in the calculation of the "number of protrusions 10 Np" and the "average height Hp of the protrusions 10". In particle 2, the average height Hp of the protrusions 10 is calculated using the following formula. Hp = (H1 + H2 + H3 + H5 + H6) / 5

[0027] In particles 2 that satisfy conditions 1-3, the contour 4 is distorted due to the large number of protrusions 10 with a large height H and the large average height of the protrusions 10. When these particles 2 are subjected to the pressurization method, they damage the insulating coating 16 of adjacent particles 2, in conjunction with their large diameter D2. The compacted magnetic core obtained from particles 2 with damaged insulating coatings 16 has inferior magnetic properties. Core loss is likely to occur in these compacted magnetic cores. From the viewpoint of magnetic properties, it is preferable to have a small number of particles 2 that satisfy conditions 1-3. From the viewpoint of magnetic properties, the ratio P2 is preferably 50% or less, more preferably 47% or less, and particularly preferably 45% or less. The ideal ratio P2 is 0%.

[0028] In powders with a P2 ratio of 50% or less, damage to the insulating film 16 can be suppressed even if the insulating film 16 is thin. Powders with a thin insulating film 16 exhibit excellent packing properties. The density of a compacted magnetic core using this powder is high. This compacted magnetic core has a high saturation magnetization. This compacted magnetic core can meet the requirements for high current applications.

[0029] In calculating the ratio P2, the powder is classified using a sieve with a mesh size of 50 μm. Fifty particles 2 are randomly selected from the particles 2 remaining on the sieve and observed under a stereomicroscope. From the projection of each particle 2, the diameter D2 and the average size Sp of the protrusions 10 are measured, and numbers N1 and N2 are counted.

[0030] [Ratio P1] In this specification, the ratio P1 is calculated using the following formula. P1 = (N3 / N) * 100 In this formula, N represents the total number of particles 2, and N3 represents the number of particles 2 with a circularity Ro of 0.8 or higher. Even when particles 2 with a large circularity Ro are subjected to the pressurization method, they are less likely to damage the insulating coating 16 of adjacent particles 2. Compacted magnetic cores obtained from powder with a large ratio P1 of particles 2 with a circularity Ro of 0.8 or higher have excellent magnetic properties. From this viewpoint, a ratio P1 of 50% or higher is preferable, 55% or higher is more preferable, and 60% or higher is particularly preferable.

[0031] The circularity Ro is calculated using the following formula. Ro = 4πS / L 2 In this formula, S is the projected area of ​​particle 2, and L is the contour length of particle 2. The area S and contour length L are measured by image analysis. As an example of an image analysis measuring instrument, the "PITA-04" product name of Seishin Corporation is given.

[0032] Regardless of the magnitude of ratio P1, a damage suppression effect can be obtained with a small ratio P2. In other words, in this embodiment, setting the value of ratio P1 is not essential.

[0033] Even with powders having a low ratio P1, damage to the insulating film 16 can be suppressed if the ratio P2 is sufficiently low. The production of powders with a low ratio P1 results in a high material yield. Therefore, powders with a low ratio P1 can be obtained at a low cost. From a cost standpoint, a ratio P1 of 80% or less is preferable, 75% or less is more preferable, and 70% or less is particularly preferable.

[0034] [Ratio P3] Figure 6 shows a magnified view of the void 18. Figure 6 also shows a third virtual circle 22. This third virtual circle 22 is the smallest circle that contains the outline 24 of the void 18 inside it. In other words, the third virtual circle 22 is the "smallest circumscribed circle" as defined by the "smallest circumscribed circle center method". In Figure 6, the symbol D3 represents the diameter of the third virtual circle 22. In this specification, this diameter D3 is referred to as the "diameter of the void 18".

[0035] In this specification, the ratio P3 is calculated using the following formula. P3 = (N4 / N1) * 100 In this formula, N1 represents the number of particles 2 whose diameter D2 is 50 μm or more. In this formula, N4 represents the number of particles 2 whose diameter D2 is 50 μm or more, and whose number of voids 18 Nv, each containing a diameter D3 of 0.1 μm or more in a single cross-section, is 2 or more.

[0036] The ratio P3 correlates with the permeability of the compacted magnetic core. From the viewpoint of the magnetic properties of the compacted magnetic core, a ratio P3 of 20% or more is preferable, 18% or less is more preferable, and 15% or less is particularly preferable. The ideal ratio P3 is 0%.

[0037] In calculating the ratio P3, the powder is classified using a sieve with a mesh size of 50 μm. The numerous particles 2 remaining on the sieve are embedded in resin and polished. From the cross-sections of the numerous particles 2 that appear on the polished surface, 50 cross-sections with a diameter of 50 μm or more are randomly selected. In each of the 50 cross-sections, the number of pores 18 with a diameter D3 of 0.1 μm or more is counted. The number of pores 18 with a diameter D3 of 0.1 μm or more in one cross-section is defined as the number Nv in that particle 2. Pores 18 that do not appear in this cross-section are not included in the number Nv.

[0038] [Material of the main part] As mentioned above, the main part 14 is made of an iron-based alloy. Iron-based alloys have excellent toughness. Therefore, this powder is suitable for the pressurization method. Various soft magnetic iron-based alloys can be used as powder.

[0039] Preferably, this iron-based alloy is Si: 2.0% by mass or more and 10.0% by mass or less, Cr: 0.0 mass% or more and 10.0 mass% or less, Al: 0.0 mass% or more and 10.0 mass% or less, and B: 0.0 mass% or more and 10.0 mass% or less It contains [the specified components]. Preferably, the remainder is Fe and unavoidable impurities.

[0040] [Material of insulating coating] The material of the coating 16 is an insulating substance. The conductivity of the coating 16 is lower than that of the main part. The coating 16 can be formed by oxidation of the surface of the main part 14. The material of the coating 16 may be an organic substance. An example of an organic substance is a polymer of a mixture of titanium alkoxides and silicon alkoxides. The coating 16 may have two or more layers.

[0041] [Manufacturing method] The production of this powder can be carried out by atomization, grinding, or other methods. Possible atomization methods include gas atomization, disc atomization, water atomization, and centrifugal atomization. Gas atomization and disc atomization are preferred from the viewpoint of suppressing the oxygen and nitrogen content in the powder.

[0042] Typical voids 18 are gas pores resulting from gas atomization. Gas pores are generated when the atomizing gas penetrates the droplet and solidifies. Helium, argon, and nitrogen are commonly used as inert gases for atomization. Since helium and argon are hardly absorbed by metals, gas pores are likely to occur in gas atomization using helium and argon gases. On the other hand, since nitrogen can be absorbed by metals, gas pores are less likely to occur in gas atomization using nitrogen gas. Furthermore, gas pores are also less likely to occur in disc atomization, where droplet formation by an inert gas is not performed. From the viewpoint of obtaining powder with a low ratio P3, gas atomization using nitrogen gas and disc atomization are preferred.

[0043] During atomization, the protrusions 10 may adhere to the core 8 before the molten metal has fully solidified. Therefore, the material of the protrusions 10 is generally the same as the material of the core 8. These protrusions 10 are integral to the core 8. Protrusions 10 may also form on the particles 2 due to other causes.

[0044] Preferably, the raw material powder obtained by atomization or the like is subjected to jet milling to obtain a powder. In jet milling, particles 2 collide with each other due to a high-speed jet stream. This collision pulverizes the protrusions 10. Therefore, a small ratio P2 can be achieved in the powder obtained by jet milling. An example of a suitable device for jet milling is the "MJM1" product name of M-Tech Chemical Co., Ltd. The protrusions 10 may also be pulverized by methods other than jet milling.

[0045] The powder after jet milling may be annealed. The strain caused in particle 2 by jet milling can be removed by annealing. Annealing is performed by holding the powder at a predetermined temperature (e.g., 600°C) for a predetermined time (e.g., 5 hours) in an atmosphere of inert gas (e.g., argon gas), and then furnace-cooling it.

[0046] When the powder is subjected to heat treatment, the surface of the powder oxidizes, and an insulating film 16 can be formed. From the viewpoint of efficiency, it is preferable that the aforementioned annealing is performed in conjunction with this heat treatment. In this case, the annealing atmosphere gas is the atmosphere (or partly the atmosphere).

[0047] [Magnetic material] One method for obtaining compacted magnetic cores from this powder is the pressurization method. In the pressurization method, the powder is placed in a mold and pressurized. This produces a molded body. Lubricants, binders, etc., may be used during pressurization. This molded body is heat-treated to obtain compacted magnetic cores. Other magnetic components besides compacted magnetic cores can also be obtained from this powder using the pressurization method.

[0048] This specification is also directed to a method for manufacturing magnetic materials. This manufacturing method is The iron-based soft magnetic powder is prepared by having a large number of particles 2, including particles 2 with a diameter of 50 μm or more, and having a ratio P2 of 50% or less calculated by the following formula. and Step of pressurizing the above powder Includes. P2 = (N2 / N1) * 100 In this formula, N1 represents the number of particles 2 with a diameter of 50 μm or more. In this formula, N2 represents the number of particles 2 with a diameter of 50 μm or more, which include a core 8 and 20 or more protrusions 10 attached to the surface of the core 8, each with a height of 1.0 μm or more, and whose average height of the protrusions is 10 μm or more. [Examples]

[0049] The effects of the soft magnetic powders described in the following examples will be clarified, but the scope disclosed herein should not be interpreted as limiting based on the description of these examples.

[0050] [Experiment 1] [Example 1] A raw material, alloy 3 as shown in Table 1 below, was prepared. 30 kg of the raw material was gas atomized with argon gas to obtain a raw material powder. This raw material powder was classified using a sieve specified in "JIS Z 8801-1" so that the particle size was between 20 μm and 150 μm. This powder was then subjected to jet milling using a jet milling apparatus (the aforementioned "MJM1") from M-Tech Chemical Co., Ltd. Compressed air pressure: 0.7 MPa Compressed air volume: 21 m³ 3 / hour(350L / min) Furthermore, this powder was annealed under the following conditions to obtain the soft magnetic powder of Example 1. Annealing removed the strain generated by the jet milling process and also formed an insulating film. The material of this film was an iron-based oxide. The annealing conditions were as follows. Atmosphere: Part of the atmosphere is replaced with argon gas (oxygen concentration: 500 ppm) Temperature at which heating begins: Room temperature (25°C) Heating rate: 0.16℃ / s Achieved temperature: 600℃ Retention time: 5 hours Cooling: Furnace cooled to room temperature

[0051] [Examples 2-8] The powder of Example 2-8 was obtained in the same manner as in Example 1, except that the materials and atomizing gas were as shown in Table 2 below.

[0052] [Examples 9-11] The materials were as shown in Table 2 below, and the powders of Examples 9-11 were obtained in the same manner as in Example 1, except that disc atomization was performed instead of gas atomization and jet milling was omitted.

[0053] [Comparative Examples 1-4] The materials and atomizing gases were as shown in Table 2 below, and the powders of Comparative Examples 1-4 were obtained in the same manner as in Example 1, except that jet milling was not performed.

[0054] [evaluation] The powder was placed in a mold and a pressure of 1520 MPa was applied to obtain a toroidal molded body. The dimensions of this molded body were as follows: Outer diameter: 28mm Inner diameter: 15mm Height: 3mm

[0055] This molded body was subjected to stress-relieving annealing to obtain a compacted magnetic core. The annealing conditions were as follows: Atmosphere: Argon gas (oxygen concentration: less than 1 ppm) Temperature at which heating begins: Room temperature (25°C) Heating rate: 0.16℃ / s Achieved temperature: 800℃ Holding time: 1 hour Cooling: Furnace cooled to room temperature The electrical resistance values ​​of the compacted magnetic cores obtained from the powders of Examples 1-11 and Comparative Examples 1-4 are 1 × 10⁻⁶. 7 Ω·cm 3 In conclusion, its insulating properties were sufficient.

[0056] The density and permeability μ' of these compacted magnetic cores were measured. Compacted magnetic cores with a high permeability μ' are less prone to core loss. Furthermore, they were graded according to the following criteria. The results are shown in Table 2 below. S: Permeability is 30 or higher. A: The magnetic permeability is between 20 and 30. B: The magnetic permeability is between 15 and 20. F: Permeability is less than 15.

[0057] [Experiment 2] [Examples 12-21] The powders of Example 12-21 were obtained in the same manner as in Example 1, except that the materials and atomizing gas were as shown in Table 3 below.

[0058] [Examples 22-26] The materials were as shown in Table 3 below, and the powders of Examples 22-26 were obtained in the same manner as in Example 1, except that disc atomization was performed instead of gas atomization and jet milling was omitted.

[0059] [Comparative Example 5-9] The materials and atomizing gases were as shown in Table 3 below, and the powders of Comparative Examples 5-9 were obtained in the same manner as in Example 1, except that jet milling was not performed.

[0060] [evaluation] A compacted magnetic core was obtained using the same method as in Experiment 1. The electrical resistance values ​​of the compacted magnetic cores obtained from the powders of Examples 12-26 and Comparative Examples 5-9 were 1 × 10⁻⁶. 7 Ω·cm 3 In conclusion, its insulating properties were sufficient.

[0061] The density and permeability μ' of this compacted magnetic core were measured. Furthermore, it was graded according to the following criteria. The results are shown in Table 3 below. S: Permeability is 25 or higher. A: The magnetic permeability is between 15 and 25. B: The magnetic permeability is between 10 and 15. F: Permeability is less than 10.

[0062] [Experiment 3] [Examples 27-35] Powders for Examples 27-35 were obtained in the same manner as in Example 1, except that the materials and atomizing gas were as shown in Table 4 below.

[0063] [Examples 36-38] The materials were as shown in Table 4 below, and the powders of Examples 36-38 were obtained in the same manner as in Example 1, except that disc atomization was performed instead of gas atomization and jet milling was omitted.

[0064] [Comparative Example 10-13] The materials and atomizing gases were as shown in Table 4 below, and the powders of Comparative Examples 10-13 were obtained in the same manner as in Example 1, except that jet milling was not performed.

[0065] [evaluation] A compacted magnetic core was obtained using the same method as in Experiment 1. The electrical resistance values ​​of the compacted magnetic cores obtained from the powders of Examples 27-35 and Comparative Examples 10-13 were 1 × 10⁻⁶. 7 Ω·cm 3 In conclusion, its insulating properties were sufficient.

[0066] The density and permeability μ' of this compacted magnetic core were measured. Furthermore, it was graded according to the following criteria. The results are shown in Table 4 below. S: Permeability is 20 or higher. A: The magnetic permeability is between 10 and 20. B: The magnetic permeability is between 5 and 10. F: Permeability is less than 5.

[0067] [Table 1]

[0068] [Table 2]

[0069] [Table 3]

[0070] [Table 4]

[0071] As shown in Table 2-4, molded articles with excellent magnetic properties can be obtained from the powders of each example. The advantages of the present invention are clear from these evaluation results. [Industrial applicability]

[0072] The powders described above are suitable for various magnetic materials. [Explanation of Symbols]

[0073] 2...particles 4. First Virtual Yen 6. Contour (of a particle) 8 cores 10...protrusion 12...Second Virtual Yen 14... Main part 16. Coating 18...Vacancies 20...Top 22...Third Virtual Yen 24... (Outline of a void)

Claims

1. It consists of many particles, These particles include particles with a diameter of 50 μm or more. An iron-based soft magnetic powder in which the ratio P2 calculated by the following formula is 50% or less. P2 = (N2 / N1) * 100 (In this formula, N1 represents the number of particles with a diameter of 50 μm or more.) (In this formula, N2 represents the number of particles that have a diameter of 50 μm or more, and that include a core and 20 or more protrusions attached to the surface of the core, each with a height of 1.0 μm or more, and whose average height of the protrusions with a height of 1.0 μm or more is 10 μm or more.)

2. The soft magnetic powder according to claim 1, wherein the ratio P1 calculated by the following formula is 50% or more. P1 = (N3 / N) * 100 (In this formula, N represents the total number of particles, and N3 represents the number of particles with a circularity of 0.8 or higher.)

3. The soft magnetic powder according to claim 2, wherein the above ratio P1 is 80% or less.

4. The soft magnetic powder according to claim 1 or 2, wherein the ratio P3 calculated by the following formula is 20% or less. P3 = (N4 / N1) * 100 (In this formula, N1 represents the number of particles with a diameter of 50 μm or more.) (In this formula, N4 represents the number of particles with a diameter of 50 μm or more, and in which the number of pores with a diameter of 0.1 μm or more in a single cross-section is 2 or more.)

5. The soft magnetic powder according to claim 1 or 2, wherein the ratio P4 calculated by the following formula is 50% or more. P4 = (N1 / N) * 100 (In this formula, N represents the total number of particles, and N1 represents the number of particles with a diameter of 50 μm or more.)

6. Each particle has a main part and an insulating film that covers all or part of the surface of this main part. The soft magnetic powder according to claim 1 or 2, wherein the material of the main part is an iron-based alloy.

7. The step of preparing an iron-based soft magnetic powder consisting of numerous particles, including particles with a diameter of 50 μm or more, and having a ratio P2 calculated by the following formula of 50% or less, and Step of pressurizing the above powder A method for manufacturing a magnetic member, comprising the features described above. P2 = (N2 / N1) * 100 (In this formula, N1 represents the number of particles with a diameter of 50 μm or more.) (In this formula, N2 represents the number of particles that have a diameter of 50 μm or more, and that include a core and 20 or more protrusions attached to the surface of the core, each with a height of 1.0 μm or more, and whose average height of the protrusions with a height of 1.0 μm or more is 10 μm or more.)

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