Method for manufacturing amorphous alloy soft magnetic powder, amorphous alloy soft magnetic powder, powder magnetic core, magnetic device, and electronic apparatus

Abstract

To provide an amorphous alloy soft magnetic powder having a low variation in coercive force between particles with different particle diameter, a method for manufacturing an amorphous alloy soft magnetic powder with which such an amorphous alloy soft magnetic powder can be efficiently manufactured, a powder magnetic core including the amorphous alloy soft magnetic powder, a magnetic device including the powder magnetic core, and an electronic apparatus including the magnetic device.SOLUTION: A method for manufacturing an amorphous alloy soft magnetic powder includes: a step of manufacturing an amorphous alloy powder comprising a composition represented by the composition formula Fea(Si1-xBx)bCc [a, b, c, and x are 78.0≤a≤82.0, 15.0≤b≤21.0, 0<c≤5.0, and 0.5≤x≤0.9] and impurities; and a step of introducing the amorphous alloy powder into a continuous rotary kiln so that its space factor is maintained within a range of 9 volume% or more and 23 volume% or less, and heating it at a temperature of 390°C or more and 475°C or less to obtain an amorphous alloy soft magnetic powder.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing amorphous alloy soft magnetic powder, amorphous alloy soft magnetic powder, a compacted magnetic core, a magnetic element, and an electronic device.

Background Art

[0002] In Patent Document 1, the soft magnetic powder according to the application example of the present invention has a composition formula Fe , , , Cr a Si b B c C d Al e Ti f Co g [However, a, b, c, d, e, f, and g are numbers representing atomic percentages, satisfying 0 < a ≤ 3.0, 5.0 ≤ b ≤ 15.0, 7.0 ≤ c ≤ 15.0, 0.1 ≤ d ≤ 3.0, 0 < e ≤ 0.016, 0 < f ≤ 0.009, 0 ≤ g ≤ 0.025.] and contains amorphous metal particles having such a composition. According to such a configuration, soft magnetic powder having good magnetic properties due to the amorphous alloy and low coercive magnetization can be obtained.

[0003] Also, Patent Document 1 discloses performing heat treatment in the manufacture of soft magnetic powder. By performing heat treatment, various defects and anisotropies (stress-induced anisotropy) introduced when manufacturing the soft magnetic powder can be reduced. Thereby, low coercive magnetization can be achieved. Furthermore, Patent Document 1 discloses that the heating temperature in the heat treatment is set to a temperature lower than the crystallization temperature of the amorphous metal particles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, from the perspective of further reducing the coercive force, the method for producing soft magnetic powder described in Patent Document 1 still has room for improvement. Specifically, the problem is that there is a large variation in the coercive force between particles with different particle sizes.

[0006] Therefore, the problem is to realize a method that can efficiently produce amorphous alloy soft magnetic powder with little variation in the coercive force between particles with different particle sizes.

Means for Solving the Problems

[0007] The method for producing amorphous alloy soft magnetic powder according to an application example of the present invention is as follows. An amorphous alloy powder composed of a composition and impurities represented by a composition formula Fe a (Si 1-x B x ) b C c [However, a, b, c, and x are such that 78.0 ≤ a ≤ 82.0, 15.0 ≤ b ≤ 21.0, 0 < c ≤ 5.0, 0.5 ≤ x ≤ 0.9.] is produced by an atomization method in a powder production step, and The amorphous alloy powder is introduced into the continuous rotary kiln so that the occupancy rate in the continuous rotary kiln is maintained within the range of 9% by volume or more and 23% by volume or less, and heat treatment is performed by heating at a temperature of 390°C or more and 475°C or less, whereby an amorphous alloy soft magnetic powder having a coercive force of 95.5 [A / m] or less (1.2 [Oe] or less) and an average particle size D50 of 3.0 μm or more and 40.0 μm or less is obtained in a heat treatment step, and has.

[0008] The amorphous alloy soft magnetic powder according to an application example of the present invention is An amorphous alloy powder composed of a composition and impurities represented by a composition formula Fe a (Si 1-x B x ) b C c[However, a, b, c, and x satisfy 78.0 ≤ a ≤ 82.0, 15.0 ≤ b ≤ 21.0, 0 < c ≤ 5.0, 0.5 ≤ x ≤ 0.9.] It is composed of a composition and impurities, The average particle size D50 is 3.0 μm or more and 40.0 μm or less, The coercive force is 95.5 [A / m] or less (1.2 [Oe] or less), When classified with a first sieve having a mesh size of 150 μm, the classified product passing through the first sieve is defined as -150 particles, When the -150 particles are classified with a second sieve having a mesh size of 75 μm, the classified product remaining on the second sieve is defined as +75 particles, and the classified product passing through the second sieve is defined as -75 particles, When the -75 particles are classified with a third sieve having a mesh size of 53 μm, the classified product remaining on the third sieve is defined as +53 particles, and the classified product passing through the third sieve is defined as -53 particles, When the -53 particles are classified with a fourth sieve having a mesh size of 25 μm, the classified product remaining on the fourth sieve is defined as +25 particles, and the classified product passing through the fourth sieve is defined as -25 particles, Among the average particle sizes D(+75) of the +75 particles, the average particle sizes D(+53) of the +53 particles, the average particle sizes D(+25) of the +25 particles, and the average particle sizes D(-25) of the -25 particles, when the coercive force of the particles with an average particle size less than D50 is Hα and the coercive force of the particles with an average particle size greater than or equal to D50 is Hβ, Hα = γHβ (the coefficient γ is 0.9 or more and 1.1 or less) is satisfied.

[0009] The compacted powder core according to the application example of the present invention is composed of the amorphous alloy soft magnetic powder according to the application example of the present invention.

[0010] The magnetic element according to the application example of the present invention is equipped with the compacted powder core according to the application example of the present invention.

[0011] The electronic device according to the application example of the present invention is equipped with the magnetic element according to the application example of the present invention.

Brief Description of the Drawings

[0012] [Figure 1] 1 is a process diagram showing the configuration of a method for producing an amorphous alloy soft magnetic powder according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a continuous rotary kiln used in the heat treatment step S104 in FIG. [Figure 3] FIG. 1 is a plan view schematically showing a toroidal type coil component. [Figure 4] FIG. 1 is a transparent perspective view schematically showing a closed magnetic circuit type coil component. [Figure 5] FIG. 1 is a perspective view showing a mobile personal computer, which is an electronic device including a magnetic element according to an embodiment. [Figure 6] FIG. 1 is a plan view showing a smartphone as an electronic device including a magnetic element according to an embodiment. [Figure 7] FIG. 1 is a perspective view showing a digital still camera, which is an electronic device including a magnetic element according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] The method for producing an amorphous alloy soft magnetic powder, the amorphous alloy soft magnetic powder, the powder core, the magnetic element, and the electronic device of the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings.

[0014] 1. Amorphous alloy soft magnetic powder First, the amorphous alloy soft magnetic powder according to the embodiment will be described.

[0015] The amorphous alloy soft magnetic powder can be used for any purpose, for example, to manufacture powder cores, which are manufactured by bonding particles of the amorphous alloy soft magnetic powder together and compacting them.

[0016] The amorphous alloy soft magnetic powder according to the embodiment has a composition formula expressed by the atomic ratio: Fe a (Si 1-x B x) b C c [However, a, b, c, and x are such that 78.0 ≤ a ≤ 82.0, 15.0 ≤ b ≤ 21.0, 0 < c ≤ 5.0, and 0.5 ≤ x ≤ 0.9.] It is composed of composition and impurities.

[0017] Moreover, the amorphous alloy soft magnetic powder according to the embodiment has an average particle diameter D50 of 3.0 μm or more and 40.0 μm or less.

[0018] Furthermore, the amorphous alloy soft magnetic powder according to the embodiment has a coercive force of 95.5 [A / m] or less (1.2 [Oe] or less).

[0019] Also, when the amorphous alloy soft magnetic powder according to the embodiment is sequentially classified using four sieves with different mesh sizes (the first sieve, the second sieve, the third sieve, and the fourth sieve), the coercive force of the obtained classified products is configured to satisfy predetermined conditions. In addition, for each sieve, the test sieve defined in JIS Z 8801-1:2019 is used. Also, the mesh size is the nominal mesh size defined in this JIS standard.

[0020] Specifically, the mesh size of the first sieve is 150 μm. And when the amorphous alloy soft magnetic powder according to the embodiment is subjected to classification using this first sieve, the classified product that has passed through the first sieve is referred to as "-150 particles".

[0021] Also, the mesh size of the second sieve is 75 μm. And when the amorphous alloy soft magnetic powder according to the embodiment is subjected to classification using this second sieve, the classified product remaining on the second sieve is referred to as "+75 particles", and the classified product that has passed through the second sieve is referred to as "-75 particles". <I D=

[0022] Furthermore, the mesh size of the third sieve is 53 μm. And when the amorphous alloy soft magnetic powder according to the embodiment is subjected to classification using this third sieve, the classified product that has passed through the third sieve is referred to as "+53 particles", and the classified product that has passed through the third sieve is referred to as "-53 particles".

[0023] The fourth sieve has a mesh size of 25 μm. When the amorphous alloy soft magnetic powder according to the embodiment is subjected to classification using this fourth sieve, the fraction remaining on the fourth sieve is referred to as "+25 particles," and the fraction passing through the fourth sieve is referred to as "-25 particles."

[0024] Here, the average particle size of the +75 particles is D(+75), the average particle size of the +53 particles is D(+53), the average particle size of the +25 particles is D(+25), and the average particle size of the -25 particles is D(-25).

[0025] Furthermore, among the average particle diameters D(+75), D(+53), D(+25), and D(-25), the coercive force of particles with an average particle diameter of less than D50 is defined as Hα. For example, if only the average particle diameter D(-25) is less than D50, the coercive force of the -25 particle should be defined as Hα.

[0026] Furthermore, among the average particle diameters D(+75), D(+53), D(+25), and D(-25), the coercive force of particles with an average particle diameter of D50 or more is defined as Hβ. For example, if the coercive force of particles with an average particle diameter D(-25) is Hα, then the coercive force of the particle group consisting of +75 particles, +53 particles, and +25 particles can be defined as Hβ.

[0027] The amorphous alloy soft magnetic powder according to the embodiment satisfies Hα=γHβ (coefficient γ is 0.9 or more and 1.1 or less).

[0028] This configuration makes it possible to obtain an amorphous alloy soft magnetic powder with little variation in coercivity between particles of different particle sizes, which allows, for example, when using the amorphous alloy soft magnetic powder to manufacture products such as dust cores, to produce products with stable characteristics.

[0029] The coefficient γ is preferably 0.9 or more and 1.0 or less, which makes it possible to realize an amorphous alloy soft magnetic powder that can be used to produce a green compact having an especially low coercive force when compacted.

[0030] If the coefficient γ is below the lower limit or above the upper limit, the difference between the coercive force Hα and the coercive force Hβ increases, resulting in a high coercive force when the amorphous alloy soft magnetic powder is compacted.

[0031] 1.1. Composition The composition of the amorphous alloy soft magnetic powder according to the embodiment will be described in detail below. As described above, the amorphous alloy soft magnetic powder according to the embodiment has a composition formula of Fe a (Si 1-x B x ) b C c This composition formula represents the ratio of the number of atoms in a composition consisting of four elements: Fe, Si, B, and C.

[0032] Fe (iron) has a significant effect on the basic magnetic properties and mechanical properties of the amorphous alloy soft magnetic powder according to the embodiment.

[0033] The content of Fe is not particularly limited, but is set so that Fe is the main component in the amorphous alloy soft magnetic powder, that is, so that the ratio of the number of atoms is the highest.

[0034] a represents the Fe content, and is 78.0≦a≦82.0, preferably 78.5≦a≦81.5, and more preferably 79.0≦a≦81.0. It corresponds to a=100−bc. If a is below the lower limit, the magnetic properties or corrosion resistance deteriorate. On the other hand, if a is above the upper limit, the amorphous alloy soft magnetic powder tends to crystallize during production. Furthermore, it becomes difficult to reduce the coercive force of the amorphous alloy soft magnetic powder.

[0035] When producing amorphous alloy soft magnetic powder from raw materials, Si (silicon) promotes amorphization and increases the magnetic permeability of the amorphous alloy soft magnetic powder, thereby achieving high magnetic permeability and low coercive force.

[0036] Boron (B) promotes amorphization when producing amorphous alloy soft magnetic powder from raw materials. In particular, by using Si and B together, the difference in atomic radii of the two elements synergistically promotes amorphization. This allows for sufficient achievement of high magnetic permeability and low coercive force.

[0037] x represents the ratio of the B content to the total Si content and B content, where the sum is 1. In the amorphous alloy soft magnetic powder according to this embodiment, 0.5≦x≦0.9, preferably 0.6≦x≦0.8. This allows the balance between the Si content and the B content to be optimized. Note that if x is below the lower limit or above the upper limit, the balance between the number of Si atoms and the number of B atoms is disrupted, making it difficult to achieve amorphization when, for example, increasing the Fe ratio to improve magnetic properties.

[0038] b represents the ratio of the total content of Si and B, and is 15.0≦b≦21.0, preferably 16.0≦b≦20.0, and more preferably 17.0≦b≦19.0. If b is below the lower limit or above the upper limit, the amorphous alloy soft magnetic powder is likely to crystallize during production.

[0039] The Si content is preferably 3.0 atomic % or more and 8.0 atomic % or less, and more preferably 4.5 atomic % or more and 6.0 atomic % or less.

[0040] The content of B is preferably 10.0 atomic % or more and 15.5 atomic % or less, and more preferably 11.5 atomic % or more and 14.5 atomic % or less.

[0041] Carbon (C) reduces the viscosity of the melt when the raw materials for amorphous alloy soft magnetic powder are melted, facilitating amorphization and pulverization. This allows for the production of amorphous alloy soft magnetic powder with small diameter and high magnetic permeability. As a result, eddy current loss can be suppressed even in the high frequency range.

[0042] c represents the content of C, where 0 < c ≤ 5.0, preferably 1.0 ≤ c ≤ 4.0, and more preferably 1.5 ≤ c ≤ 3.5. When c is below the lower limit value, the viscosity of the melt does not decrease sufficiently, and the shape of the particles becomes irregular. For this reason, the filling property during powder pressing decreases, and the saturation magnetic flux density and magnetic permeability of the compacted powder cannot be increased sufficiently. On the other hand, when c exceeds the upper limit value, crystallization tends to occur during the production of the amorphous alloy soft magnetic powder.

[0043] The amorphous alloy soft magnetic powder according to the embodiment may contain impurities in addition to the above elements. The total content of impurities is preferably 1.0 mass% or less, more preferably 0.2 mass% or less, and even more preferably 0.1 mass% or less. Within this range, the effects exhibited by the embodiment are less likely to be inhibited by the impurities, so the inclusion is acceptable.

[0044] As described above, the composition of the amorphous alloy soft magnetic powder according to the embodiment has been described in detail. The above composition and impurities are specified by the following analysis methods.

[0045] Examples of the analysis methods include atomic absorption spectrometry for iron and steel specified in JIS G 1257:2000, ICP emission spectrometry for iron and steel specified in JIS G 1258:2007, spark discharge emission spectrometry for iron and steel specified in JIS G 1253:2002, fluorescent X-ray analysis for iron and steel specified in JIS G 1256:1997, and gravimetric, titrimetric, and absorptiometric methods specified in JIS G 1211~G 1237.

[0046] Specifically, for example, a solid emission spectrometry device manufactured by SPECTRO, particularly a spark discharge emission spectrometry device, model: SPECTROLAB, type: LAVMB08A, and an ICP device CIROS120 type manufactured by Rigaku Corporation can be mentioned.

[0047] In particular, when identifying carbon (C) and sulfur (S), the oxygen flow combustion (high-frequency induction heating furnace combustion)-infrared absorption method specified in JIS G 1211:2011 is also used. Specifically, the LECO CS-200 carbon / sulfur analyzer can be used.

[0048] Furthermore, when specifying N (nitrogen) and O (oxygen), the methods for determining nitrogen in iron and steel specified in JIS G 1228:1997 and the general method for determining oxygen in metallic materials specified in JIS Z 2613:2006 are also used. Specific examples include the LECO oxygen and nitrogen analyzer TC-300 / EF-300.

[0049] If necessary, an insulating film may be formed on the surface of each particle of the obtained amorphous alloy soft magnetic powder. The material of this insulating film is not particularly limited, but examples thereof include inorganic materials such as phosphates such as magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, and cadmium phosphate, and silicates such as sodium silicate.

[0050] 1.2.Powder characteristics The amorphous alloy soft magnetic powder according to the embodiment has an average particle size D50 of 3.0 μm or more and 40.0 μm or less, preferably 10.0 μm or more and 40.0 μm or less, and more preferably 20.0 μm or more and 40.0 μm or less. Such amorphous alloy soft magnetic powder is prevented from crystallizing by heat treatment and stress-strain is sufficiently alleviated. This makes it easier to achieve a low coercive force.

[0051] In particular, when the average particle size D50 is set to 20.0 μm or more and 40.0 μm or less, an amorphous alloy soft magnetic powder suitable for use in combination with other soft magnetic powders having smaller average particle sizes is obtained. In other words, when an amorphous alloy soft magnetic powder having an average particle size D50 within this range is mixed with other soft magnetic powders having smaller diameters and compacted, it contributes to a higher density of the powder core than when each powder is compacted alone. Moreover, because amorphous alloy soft magnetic powders having an average particle size D50 within this range have low coercivity even when they are large in diameter, they contribute to the realization of a powder core with low coercivity.

[0052] The average particle size D50 of the amorphous alloy soft magnetic powder is determined as the particle size at which the cumulative size from the smallest diameter side is 50% in the volume-based particle size distribution obtained by laser diffraction.

[0053] If the average particle size D50 of the amorphous alloy soft magnetic powder is below the lower limit, the particle size becomes too small, which may result in insufficient filling during powder compaction. Furthermore, there is a risk of crystallization due to heat treatment. On the other hand, if the average particle size D50 of the amorphous alloy soft magnetic powder exceeds the upper limit, the particle size becomes too large, which may result in insufficient amorphization. Furthermore, there is a risk that stress-strain relaxation due to heat treatment may be insufficient, making it difficult to achieve a low coercive force.

[0054] Furthermore, for amorphous alloy soft magnetic powders, when the volume-based particle size distribution obtained by laser diffraction is measured, the particle size at the 10% cumulative particle size from the smallest diameter side is defined as D10, and the particle size at the 90% cumulative particle size from the smallest diameter side is defined as D90. (D90-D10) / D50 is preferably 1.3 or more and 3.0 or less, and more preferably 1.8 or more and 2.5 or less. (D90-D10) / D50 is an index indicating the degree of broadness of the particle size distribution. By keeping this index within the above range, the packing property of the amorphous alloy soft magnetic powder is particularly good. This results in an amorphous alloy soft magnetic powder that can be used to manufacture magnetic elements with particularly high magnetic permeability.

[0055] 1.3.Magnetic Properties The coercive force of the amorphous alloy soft magnetic powder according to the embodiment is 95.5 [A / m] or less (1.2 [Oe] or less), preferably 23.9 [A / m] or more (0.3 [Oe] or more) and 95.5 [A / m] or less (1.2 [Oe] or less), more preferably 31.8 [A / m] or more (0.4 [Oe] or more) and 87.5 [A / m] or less (1.1 [Oe] or less), and even more preferably 39.8 [A / m] or more (0.5 [Oe] or more) and 79.6 [A / m] or less (1.0 [Oe] or less).

[0056] By using such amorphous alloy soft magnetic powder with particularly low coercive force, it is possible to realize a magnetic element that can sufficiently suppress hysteresis loss.

[0057] If the coercive force is below the lower limit, it becomes difficult to stably produce the amorphous alloy soft magnetic powder, and if the coercive force is too high, the magnetic permeability may be affected. On the other hand, if the coercive force exceeds the upper limit, the hysteresis loss increases, which may result in an increase in the iron loss of the magnetic element.

[0058] The coercive force of the amorphous alloy soft magnetic powder can be measured by a vibrating sample magnetometer such as TM-VSM1230-MHHL manufactured by Tamagawa Seisakusho Co., Ltd.

[0059] The saturation magnetic flux density of the amorphous alloy soft magnetic powder according to the embodiment is preferably 1.25 T or more and 1.85 T or less, and more preferably 1.45 T or more and 1.65 T or less. By using such amorphous alloy soft magnetic powder with a high saturation magnetic flux density, it is possible to reduce the size and increase the output of the magnetic element.

[0060] If the saturation magnetic flux density is below the lower limit, it may be difficult to miniaturize the magnetic element and increase its output, whereas if the saturation magnetic flux density is above the upper limit, it may be difficult to stably produce the amorphous alloy soft magnetic powder, and if the saturation magnetic flux density is too high, it may affect the coercivity.

[0061] The saturation magnetic flux density of the amorphous alloy soft magnetic powder is measured by the following method. First, the true specific gravity ρ of the soft magnetic powder is measured using a fully automatic gas replacement type densitometer, AccuPyc1330 manufactured by Micromeritics. Next, the maximum magnetization Mm of the soft magnetic powder is measured using a vibrating sample type magnetometer, VSM system TM-VSM1230-MHHL manufactured by Tamagawa Seisakusho Co., Ltd. Then, the saturation magnetic flux density Bs is calculated by the following formula. Bs = 4π / 10000 × ρ × Mm

[0062] 2. Method for manufacturing amorphous alloy soft magnetic powder Next, a method for manufacturing the amorphous alloy soft magnetic powder according to the embodiment will be described.

[0063] FIG. 1 is a process diagram showing the configuration of a method for manufacturing an amorphous alloy soft magnetic powder according to the embodiment.

[0064] The method for manufacturing the amorphous alloy soft magnetic powder shown in FIG. 1 includes a powder manufacturing step S102 and a heat treatment step S104.

[0065] 2.1. Powder manufacturing step In the powder manufacturing step S102, powder (amorphous alloy powder) before heat treatment is manufactured.

[0066] The amorphous alloy powder is a powder composed of an amorphous alloy having a composition represented by an atomic ratio composition formula Fe a (Si 1-x B x ) b C c [where a, b, c, and x satisfy 78.0 ≤ a ≤ 82.0, 15.0 ≤ b ≤ 21.0, 0 < c ≤ 5.0, and 0.5 ≤ x ≤ 0.9.] and impurities.

[0067] Such amorphous alloy powder may have stress distortion during the manufacturing process, etc. Therefore, by subjecting the amorphous alloy powder to a heat treatment as described below, the stress distortion is alleviated and the coercive force is reduced.

[0068] The amorphous alloy powder has a crystallinity of less than 50%, preferably 30% or less, in each particle. The crystallinity is calculated based on the following formula by obtaining an X-ray diffraction spectrum of the amorphous alloy powder. Crystallinity = {crystal-derived intensity / (crystal-derived intensity + amorphous-derived intensity)} x 100

[0069] Amorphous alloy powder is produced by atomization. Atomization is a method of producing powder by pulverizing and cooling molten raw materials by colliding them with a fluid such as a liquid or gas injected at high speed. Atomization methods include water atomization, gas atomization, and rotary water atomization, depending on the type of coolant and the configuration of the device. Of these, amorphous alloy powder is preferably produced by water atomization or rotary water atomization, and more preferably by rotary water atomization.

[0070] In this specification, the term "water atomization method" refers to a method for producing amorphous alloy powder by using water as a coolant, spraying it in an inverted cone shape that converges to one point, and then causing molten metal to flow down and collide with the converging point.

[0071] On the other hand, the "rotary water atomization method" in this specification is a method in which water is jetted and supplied along the inner circumferential surface of a cooling cylinder and swirled to form a water layer on the inner circumferential surface, and the scattered molten metal is brought into contact with this water layer. The finely powdered molten metal is taken into the water layer and is rapidly cooled and solidified.

[0072] In the rotary water jet atomization method, a very high cooling rate can be stably maintained by continuously supplying water, and therefore, even when producing amorphous alloy powder having a relatively large average particle size D50 of 20.0 μm or more and 40.0 μm or less, a sufficient cooling rate can be ensured, thereby obtaining amorphous alloy powder having a large particle size and a good degree of amorphization.

[0073] The amorphous alloy powder may be subjected to classification treatment as needed. Examples of classification treatment methods include dry classification such as sieving classification, inertial classification, centrifugal classification, and air classification, and wet classification such as sedimentation classification. In addition, classification treatment may be performed after the heat treatment step described below.

[0074] 2.2.Heat treatment process In the heat treatment step S104, the amorphous alloy powder is heat treated, which can relieve stress strain in the amorphous alloy powder and produce soft magnetic amorphous alloy powder with low coercive force. In this embodiment, the heat treatment is carried out in a continuous rotary kiln.

[0075] FIG. 2 is a cross-sectional view schematically showing the continuous rotary kiln 1 used in the heat treatment step S104 of FIG.

[0076] The continuous rotary kiln 1 shown in FIG. 2 includes a rotary drum 110, a raw material charging section 120, a treated product discharge section 130, a gas inlet section 140, and a gas discharge section 150.

[0077] The rotating drum 110 is a cylindrical heating furnace with one end connected to the raw material input section 120 and the other end connected to the processed product discharge section 130. The rotating drum 110 is driven to rotate about a rotation axis AX by a drive section (not shown). This allows the workpiece 200 (amorphous alloy powder) to be heated while being stirred. Furthermore, the workpiece 200 fed from the raw material input section 120 is transported to the processed product discharge section 130 by the rotational drive.

[0078] The raw material input section 120 inputs the object 200 to be heat-treated into the rotary drum 110 .

[0079] The treated object discharge section 130 discharges the heat-treated object 200 from the rotary drum 110 .

[0080] Gas inlet 140 introduces gas G into rotary drum 110. Examples of gas G include inert gases such as nitrogen and argon, oxidizing gases such as air, and reducing gases such as hydrogen. The gas discharge section 150 discharges the gas G from inside the rotary drum 110 .

[0081] In this embodiment, the operation of the raw material charging section 120 is controlled so that the material 200 is charged at a predetermined speed. Specifically, the material 200 is charged so that the space factor of the material 200 in the continuous rotary kiln 1 is maintained within a range of 9% by volume or more and 23% by volume or less.

[0082] By setting the space factor of the workpiece 200 within the above range, it is possible to apply a uniform amount of heat during the heat treatment, regardless of the particle size of the workpiece 200. This allows the progress of the heat treatment to be uniform. This allows the stress-strain of the amorphous alloy powder to be evenly alleviated, and defects such as crystallization caused by uneven heating to be suppressed. As a result, it is possible to efficiently produce amorphous alloy soft magnetic powder with little variation in coercivity between particles of different particle sizes.

[0083] Furthermore, in the continuous rotary kiln 1, the objects 200 to be treated can be continuously fed into the rotating drum 110, and the heat-treated objects 200 can be continuously discharged. By using the rotating drum 110, the objects 200 to be treated can be heat-treated while being stirred, which makes it possible to make the progress of the heat treatment particularly uniform.

[0084] The space factor is preferably 10% by volume or more and 21% by volume or less, and more preferably 12% by volume or more and 19% by volume or less. This space factor is calculated as the ratio of the volume of the object to be processed 200 to the internal volume of the rotating drum 110.

[0085] The heat treatment temperature is set to 390° C. or higher and 475° C. or lower, preferably 420° C. or higher and 470° C. or lower, and more preferably 430° C. or higher and 465° C. If the heat treatment temperature is within the above range, the stress strain can be sufficiently alleviated while suppressing crystallization of the amorphous alloy powder.

[0086] If the heat treatment temperature is below the lower limit, the stress strain cannot be sufficiently alleviated, resulting in an increased coercive force, whereas if the heat treatment temperature is above the upper limit, the amorphous alloy powder may crystallize.

[0087] The time for maintaining the above temperature during the heat treatment (heat treatment time) is preferably from 15 to 150 minutes, more preferably from 30 to 120 minutes, and even more preferably from 45 to 90 minutes. If the heat treatment time is within the above range, stress strain can be sufficiently alleviated while suppressing crystallization of the amorphous alloy powder.

[0088] If the heat treatment time is less than the lower limit, the stress strain may not be sufficiently alleviated, and the coercive force may increase, whereas if the heat treatment time is more than the upper limit, no further effect may be expected, and the energy efficiency of the heat treatment may decrease.

[0089] The pressure inside the continuous rotary kiln 1 during heat treatment is not particularly limited and may be either positive or negative, but is preferably 90 kPa or more and 110 kPa or less. A pressure in this range is atmospheric pressure or close to it, so unevenness in the heat treatment due to pressure fluctuations can be suppressed. Note that this pressure is the pressure inside the rotary drum 110.

[0090] Furthermore, it is preferable to introduce an inert gas, and more preferably nitrogen gas, into the rotating drum 110. This makes it possible to control the oxygen concentration inside the rotating drum 110 and suppress oxidation of the workpiece 200 during heat treatment.

[0091] The flow rate of the inert gas to be introduced is set appropriately depending on the volume of the rotary drum 110, the amount of the object 200 to be treated, and the like.

[0092] The oxygen volume concentration in the continuous rotary kiln 1 during heat treatment is not particularly limited, but is preferably 100 ppm to 1500 ppm, more preferably 100 ppm to 1000 ppm, and even more preferably 100 ppm to 700 ppm. If the oxygen volume concentration is within the above range, oxidation of the amorphous alloy powder during heat treatment can be more reliably suppressed. Furthermore, if an oxide film is formed, stress-strain relaxation may be hindered. Taking this into consideration, if the oxygen volume concentration is within the above range, the coercivity of the amorphous alloy soft magnetic powder can be more reliably reduced by heat treatment.

[0093] If the oxygen volume concentration is less than the lower limit, the continuous rotary kiln 1 is required to be highly airtight, which may reduce the efficiency of the heat treatment or hinder the continuity of the heat treatment.

[0094] 3. Powder cores and magnetic elements Next, the powder magnetic core and the magnetic element according to the embodiment will be described.

[0095] The magnetic element according to the embodiment can be applied to various magnetic elements having a magnetic core, such as a choke coil, an inductor, a noise filter, a reactor, a transformer, a motor, an actuator, a solenoid valve, a generator, etc. Furthermore, the powder magnetic core according to the embodiment can be applied to the magnetic cores provided in these magnetic elements.

[0096] Two types of coil components will be described below as representative examples of magnetic elements. 3.1.Toroidal type First, a toroidal type coil component, which is a magnetic element according to the embodiment, will be described.

[0097] Fig. 3 is a plan view schematically showing a toroidal-type coil component 10. The coil component 10 shown in Fig. 3 has a ring-shaped powder core 11 and a conductive wire 12 wound around this powder core 11.

[0098] The powder magnetic core 11 is obtained by mixing the aforementioned amorphous alloy soft magnetic powder with a binder and compacting the resulting mixture. The powder magnetic core 11 is a compact containing the amorphous alloy soft magnetic powder according to the embodiment, and therefore has low coercivity. A coil component 10 including such a powder magnetic core 11 has low iron loss and contributes to power saving in electronic devices.

[0099] Examples of constituent materials of the binder used to produce the powder magnetic core 11 include organic materials such as silicone resins, epoxy resins, phenolic resins, polyamide resins, polyimide resins, and polyphenylene sulfide resins, and inorganic materials such as phosphates such as magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, and cadmium phosphate, and silicates such as sodium silicate.

[0100] The conductive wire 12 may be made of a highly conductive material, such as a metal material containing Cu, Al, Ag, Au, Ni, etc. If necessary, an insulating film may be provided on the surface of the conductive wire 12.

[0101] The shape of the powder magnetic core 11 is not limited to the ring shape shown in FIG. 3, but may be, for example, a shape in which a part of the ring is missing, or a shape in which the longitudinal direction is linear.

[0102] Furthermore, the powder magnetic core 11 may contain soft magnetic powder other than the amorphous alloy soft magnetic powder according to the embodiment described above, or non-magnetic powder, as needed.

[0103] 3.2.Closed magnetic circuit type Next, a closed magnetic circuit type coil component, which is a magnetic element according to the embodiment, will be described. FIG. 4 is a see-through perspective view that schematically shows a coil component 20 of a closed magnetic circuit type.

[0104] The closed magnetic circuit type coil component 20 will be described below, but the following description will focus on the differences from the toroidal type coil component 10, and a description of similar points will be omitted.

[0105] 4 includes a chip-shaped powder core 21 and a coil-shaped conductive wire 22 embedded inside the powder core 21. The powder core 21 is a compact containing the amorphous alloy soft magnetic powder according to the embodiment, and therefore has low coercivity. The coil component 20 including such a powder core 21 has low iron loss and contributes to power saving in electronic devices.

[0106] The powder magnetic core 21 may contain soft magnetic powder other than the amorphous alloy soft magnetic powder according to the embodiment described above, or non-magnetic powder, as needed.

[0107] 4.Electronic equipment Next, an electronic device including the magnetic element according to the embodiment will be described with reference to FIGS.

[0108] 5 is a perspective view showing a mobile personal computer 1100, which is an electronic device including the magnetic element 1000 according to the embodiment. The personal computer 1100 shown in FIG. 5 includes a main body 1104 including a keyboard 1102, and a display unit 1106 including a display unit 100. The display unit 1106 is rotatably supported on the main body 1104 via a hinge structure. Such a personal computer 1100 includes a magnetic element 1000, such as a choke coil or inductor for a switching power supply, or a motor, built in.

[0109] Fig. 6 is a plan view showing a smartphone 1200, which is an electronic device including the magnetic element 1000 according to the embodiment. The smartphone 1200 shown in Fig. 6 includes a plurality of operation buttons 1202, an earpiece 1204, and a mouthpiece 1206. A display unit 100 is disposed between the operation buttons 1202 and the earpiece 1204. Such a smartphone 1200 includes a magnetic element 1000, such as an inductor, a noise filter, or a motor, built in.

[0110] 7 is a perspective view showing a digital still camera 1300, which is an electronic device including the magnetic element 1000 according to the embodiment. The digital still camera 1300 photoelectrically converts an optical image of a subject using an imaging element such as a CCD (Charge Coupled Device) to generate an imaging signal.

[0111] 7 includes a display unit 100 provided on the back of a case 1302. The display unit 100 functions as a viewfinder that displays an object as an electronic image. A light receiving unit 1304 including an optical lens, a CCD, etc. is provided on the front side of the case 1302, i.e., the back side in the figure.

[0112] When the photographer checks the subject image displayed on the display unit 100 and presses the shutter button 1306, the image signal from the CCD at that time is transferred to and stored in memory 1308. This digital still camera 1300 also incorporates magnetic elements 1000 such as inductors and noise filters.

[0113] Examples of electronic devices according to the embodiments include the personal computer of FIG. 5, the smartphone of FIG. 6, and the digital still camera of FIG. 7, as well as mobile phones, tablet terminals, watches, inkjet ejection devices such as inkjet printers, laptop personal computers, televisions, video cameras, video tape recorders, car navigation devices, pagers, electronic organizers, electronic dictionaries, calculators, electronic game devices, word processors, workstations, videophones, security television monitors, electronic binoculars, POS terminals, medical devices such as electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasound diagnostic devices, and electronic endoscopes, fish finders, various measuring devices, instruments for vehicles, aircraft, and ships, mobile object control devices such as automobile control devices, aircraft control devices, railway vehicle control devices, and ship control devices, and flight simulators.

[0114] Such electronic devices include the magnetic element according to the embodiment, thereby enjoying the effect of the magnetic element, namely low iron loss, and achieving power saving in the electronic devices.

[0115] 5. Effects of the embodiment As described above, the method for producing the amorphous alloy soft magnetic powder according to the embodiment includes the powder production step S102 and the heat treatment step S104. In the powder production step S102, a composition formula Fe a (Si 1-x B x ) b C c[However, a, b, c, and x satisfy 78.0 ≤ a ≤ 82.0, 15.0 ≤ b ≤ 21.0, 0 < c ≤ 5.0, and 0.5 ≤ x ≤ 0.9.] An amorphous alloy powder composed of the composition and impurities is produced by an atomization method. In the heat treatment step S104, the amorphous alloy powder (the object to be treated 200) is introduced into the continuous rotary kiln 1 so that the occupancy rate in the continuous rotary kiln 1 is maintained within the range of 9% by volume or more and 23% by volume or less, and heat treatment is performed by heating at a temperature of 390°C or more and 475°C or less, thereby obtaining an amorphous alloy soft magnetic powder having a coercive force of 95.5 [A / m] or less (1.2 [Oe] or less) and an average particle size D50 of 3.0 μm or more and 40.0 μm or less.

[0116] According to such a configuration, the stress strain of the amorphous alloy powder can be sufficiently relaxed, and an amorphous alloy soft magnetic powder with little variation in coercive force between particles with different particle sizes can be efficiently produced.

[0117] In the method for producing an amorphous alloy soft magnetic powder according to the above embodiment, the heat treatment time is 15 minutes or more and 150 minutes or less.

[0118] According to such a configuration, while suppressing the crystallization of the amorphous alloy powder, the stress strain can be sufficiently relaxed.

[0119] In the method for producing an amorphous alloy soft magnetic powder according to the above embodiment, the coercive force of the amorphous alloy soft magnetic powder is 39.8 [A / m] or more (0.5 [Oe] or more) and 79.6 [A / m] or less (1.0 [Oe] or less).

[0120] According to such a configuration, an amorphous alloy soft magnetic powder capable of producing a magnetic element capable of sufficiently suppressing hysteresis loss can be obtained.

[0121] In the method for producing an amorphous alloy soft magnetic powder according to the above embodiment, the amorphous alloy powder is a powder produced by a rotating water flow atomization method. Also, the average particle size D50 of the amorphous alloy soft magnetic powder is 20.0 μm or more and 40.0 μm or less.

[0122] According to this configuration, an extremely high cooling rate can be stably maintained, and therefore, even when producing amorphous alloy powder having a relatively large average particle size D50 of 20.0 μm or more and 40.0 μm or less, a sufficient cooling rate can be ensured, thereby obtaining amorphous alloy powder having a large particle size and a good degree of amorphization.

[0123] In the manufacturing method of the amorphous alloy soft magnetic powder according to the embodiment, the pressure inside the continuous rotary kiln 1 during the heat treatment is 90 kPa or more and 110 kPa or less, and the oxygen volume concentration inside the continuous rotary kiln 1 during the heat treatment is 100 ppm or more and 1500 ppm or less.

[0124] With this configuration, the pressure inside the continuous rotary kiln 1 is atmospheric pressure or close to it, which prevents unevenness in the heat treatment due to pressure fluctuations. Furthermore, if the oxygen volume concentration is within the above range, oxidation of the amorphous alloy powder during the heat treatment can be more reliably prevented. This allows the amorphous alloy soft magnetic powder to have a lower coercive force through the heat treatment more reliably.

[0125] The amorphous alloy soft magnetic powder according to the embodiment has a composition formula expressed by the atomic ratio: Fe a (Si 1-x B x ) b C c[However, a, b, c, and x satisfy 78.0 ≤ a ≤ 82.0, 15.0 ≤ b ≤ 21.0, 0 < c ≤ 5.0, and 0.5 ≤ x ≤ 0.9.] It is composed of composition and impurities. Also, the amorphous alloy soft magnetic powder according to the embodiment has an average particle size D50 of 3.0 μm or more and 40.0 μm or less, and a coercive force of 95.5 [A / m] or less (1.2 [Oe] or less). Further, when the amorphous alloy soft magnetic powder according to the embodiment is classified with a first sieve having a mesh size of 150 μm, the classified product passing through the first sieve is defined as -150 particles. When the -150 particles are classified with a second sieve having a mesh size of 75 μm, the classified product remaining on the second sieve is defined as +75 particles, the classified product passing through the second sieve is defined as -75 particles. When the -75 particles are classified with a third sieve having a mesh size of 53 μm, the classified product remaining on the third sieve is defined as +53 particles, the classified product passing through the third sieve is defined as -53 particles. When the -53 particles are classified with a fourth sieve having a mesh size of 25 μm, the classified product remaining on the fourth sieve is defined as +25 particles, and the classified product passing through the fourth sieve is defined as -25 particles.

[0126] Then, among the average particle sizes D(+75) of the +75 particles, D(+53) of the +53 particles, D(+25) of the +25 particles, and D(-25) of the -25 particles, the coercive force of the particles with an average particle size less than D50 is defined as Hα, and the coercive force of the particles with an average particle size greater than or equal to D50 is defined as Hβ. At this time, the amorphous alloy soft magnetic powder according to the embodiment satisfies Hα = γHβ (the coefficient γ is 0.9 or more and 1.1 or less).

[0127] According to such a configuration, an amorphous alloy soft magnetic powder with less variation in coercive force between particles with different particle sizes can be obtained.

[0128] In the amorphous alloy soft magnetic powder according to the embodiment, when the maximum magnetization measured using a vibrating sample magnetometer is Mm [emu / g] and the true density is ρ [g / cm 3 , the saturation magnetic flux density Bs [T] obtained by 4π / 10000 × ρ × Mm = Bs is 1.25 [T] or more and 1.85 [T] or less.

[0129] According to this configuration, an amorphous alloy soft magnetic powder can be obtained that allows for miniaturization and high output of magnetic elements.

[0130] The powder magnetic core according to the embodiment contains the amorphous alloy soft magnetic powder according to the embodiment.

[0131] This configuration makes it possible to obtain a powder magnetic core with low coercivity, thereby realizing a magnetic element with low core loss.

[0132] The magnetic element according to the embodiment includes the powder magnetic core according to the embodiment. With this configuration, a magnetic element with low iron loss can be obtained, which can contribute to power saving in electronic devices.

[0133] The electronic device according to the embodiment includes the magnetic element according to the embodiment. With this configuration, it is possible to take advantage of the low iron loss effect of the magnetic element and to achieve power saving in electronic devices.

[0134] The method for producing an amorphous alloy soft magnetic powder, the amorphous alloy soft magnetic powder, the powder magnetic core, the magnetic element, and the electronic device of the present invention have been described above based on preferred embodiments, but the present invention is not limited thereto. For example, the powder magnetic core and the magnetic element of the present invention may be configured such that each part of the above-described embodiments is replaced with any component having the same function, or any component may be added to the above-described embodiments.

[0135] In the above embodiment, a dust core has been described as an example of an application of the amorphous alloy soft magnetic powder of the present invention, but the application is not limited to this and may be, for example, a magnetic fluid, a magnetic shielding sheet, a magnetic head, or other magnetic device. The shapes of the dust core and the magnetic element are also not limited to those shown in the drawings and may be any shape.

[0136] Furthermore, the method for producing the amorphous alloy soft magnetic powder of the present invention may be such that any step for any purpose is added to the above-described embodiment. [Example]

[0137] Next, specific examples of the present invention will be described. 6. Preparation of amorphous alloy soft magnetic powder 6.1. Sample No. 1 First, the raw materials were melted in a high-frequency induction furnace and pulverized by a rotary water jet atomization method to obtain amorphous alloy powder. The obtained amorphous alloy powder had the composition formula Fe a (Si 1-x B x ) b C c The powder was composed of the following composition and impurities: [a=80.0, b=18.0, c=2.0, x=0.7].

[0138] Next, the obtained amorphous alloy powder was subjected to heat treatment using a continuous rotary kiln under the conditions shown in Table 1. In this way, an amorphous alloy soft magnetic powder was obtained.

[0139] Next, the particle size distribution of the obtained amorphous alloy soft magnetic powder was obtained. The obtained results are shown in Table 1. The particle size distribution was obtained using a laser diffraction particle size distribution measuring device, Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd.

[0140] 6.2. Samples No. 2 to 16 Amorphous alloy soft magnetic powder was obtained in the same manner as Sample No. 1, except that the heat treatment conditions were changed as shown in Table 1 or Table 2. The inverted conical water flow shown in Table 2 refers to the aforementioned "water atomization method."

[0141] 6.3. Sample No. 17 First, the raw materials were melted in a high-frequency induction furnace and then pulverized by a rotary water jet atomization method to obtain amorphous alloy powder. The obtained amorphous alloy powder had the composition and impurities shown in Table 3. The composition was determined using a SPECTRO solid-state optical emission spectrometer, model: SPECTROLAB, type: LAVMB08A.

[0142] Next, the obtained amorphous alloy powder was subjected to heat treatment using a continuous rotary kiln under the conditions shown in Table 3. In this way, an amorphous alloy soft magnetic powder was obtained.

[0143] 6.4. Samples No. 18-25 Amorphous alloy soft magnetic powder was obtained in the same manner as in Sample No. 17, except that the composition of the amorphous alloy powder was changed as shown in Table 3.

[0144] In Tables 1 to 3, among the amorphous alloy soft magnetic powders of each sample number, those whose manufacturing method corresponds to the present invention are indicated as "Examples," and those that do not correspond to the present invention are indicated as "Comparative Examples."

[0145] 7. Evaluation of amorphous alloy soft magnetic powder 7.1.Coercive force The coercive force of the amorphous alloy soft magnetic powder obtained in each example and comparative example was measured. The measurement results are shown in Tables 1 to 3.

[0146] 7.2. Variation in coercive force The amorphous alloy soft magnetic powders obtained in each Example and Comparative Example were sieved through a first sieve, a second sieve, a third sieve, and a fourth sieve to obtain classified samples. Next, the coercive force Hα and the coercive force Hβ were calculated using the method described above, and the coefficient γ was calculated. The coefficient γ was then evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 1 to 3.

[0147] A: The variation in coercive force is particularly small (coefficient γ is 0.9 or more and 1.0 or less) B: Coercive force variation is relatively small (coefficient γ is greater than 1.0 and less than 1.1) C: Large variation in coercive force (less than 0.9 or more than 1.1)

[0148] 7.3.Saturation magnetic flux density The saturation magnetic flux density of the amorphous alloy soft magnetic powder obtained in each example and comparative example was measured. The measurement results were evaluated in accordance with the following evaluation criteria. The evaluation results are shown in Tables 1 to 3.

[0149] A: The saturation magnetic flux density is between 1.45T and 1.85T. B: Saturation magnetic flux density is 1.25T or more and less than 1.45T C: Saturation magnetic flux density is less than 1.25T

[0150] [Table 1]

[0151] [Table 2]

[0152] [Table 3]

[0153] As shown in Tables 1 to 3, the amorphous alloy soft magnetic powders obtained in each example were found to have lower coercive force and less variation in coercive force than the amorphous alloy soft magnetic powders obtained in each comparative example.

[0154] 8. Preparation of amorphous alloy soft magnetic powder 8.1. Comparative example A First, the raw materials were melted in a high-frequency induction furnace and pulverized by a rotary water jet atomization method to obtain amorphous alloy powder. The obtained amorphous alloy powder had the composition formula Fe a (Si 1-x B x ) bC c The powder was composed of the following composition and impurities: [a=80.0, b=18.0, c=2.0, x=0.7].

[0155] Next, the obtained amorphous alloy powder was subjected to heat treatment using a batch-type heat treatment furnace under the conditions shown in Table 4. In this way, amorphous alloy soft magnetic powder was obtained.

[0156] Next, the average particle size D50 and coercive force of the obtained amorphous alloy soft magnetic powder were measured. The results are shown in Table 4.

[0157] 8.2. Comparative Examples B and C and Examples A to C Amorphous alloy soft magnetic powder was obtained in the same manner as in Comparative Example A, except that the heat treatment conditions were as shown in Table 4.

[0158] Next, the average particle size D50 and coercive force of the obtained amorphous alloy soft magnetic powder were measured. The results are shown in Table 4.

[0159] 9. Evaluation of amorphous alloy soft magnetic powder 9.1. Obtaining the characteristics of the fraction The amorphous alloy soft magnetic powders of Comparative Examples A to C and Examples A to C were classified using the first, second, third, and fourth sieves by the method described above.

[0160] Next, the average particle diameters D(+75), D(+53), D(+25), and D(-25) of the classified particles and the coercive force of each particle were obtained. The results are shown in Table 4.

[0161] 9.2.Evaluation of coercive force variation The coercive force Hα, coercive force Hβ, and coefficient γ were calculated from the obtained coercive force of each classified material. The calculated coefficient γ was then evaluated in accordance with the following evaluation criteria. The evaluation results are shown in Table 4.

[0162] A: The variation in coercive force is particularly small (coefficient γ is 0.9 or more and 1.0 or less) B: Coercive force variation is relatively small (coefficient γ is greater than 1.0 and less than 1.1) C: Large variation in coercive force (less than 0.9 or more than 1.1)

[0163] [Table 4]

[0164] As shown in Table 4, the amorphous alloy soft magnetic powders obtained in each example had an index (coefficient γ) representing the variation in coercivity determined from each classification within a predetermined range, and it was found that the variation was smaller than that of the amorphous alloy soft magnetic powders obtained in each comparative example. It was also found that the coercivity of each classification was kept low in the amorphous alloy soft magnetic powders obtained in each example. [Explanation of symbols]

[0165] 1...continuous rotary kiln, 10...coil component, 11...powder magnetic core, 12...conductor, 20...coil component, 21...powder magnetic core, 22...conductor, 100...display unit, 110...rotating drum, 120...raw material input unit, 130...processed product discharge unit, 140...gas inlet unit, 150...gas outlet unit, 200...processed object, 1000...magnetic element, 1100...personal computer, 1102...keyboard, 1104...main body, 1106...display unit, 1200...smartphone, 1202...operation button, 1204...earpiece, 1206...mouthpiece, 1300...digital still camera, 1302...case, 1304...light receiving unit, 1306...shutter button, 1308...memory, AX...rotating shaft, G...gas, S102...powder manufacturing process, S104...heat treatment process

Claims

1. Composition formula expressed in atomic ratio: Fe ａ (Si １－ｘ B ｘ ) ｂ C ｃ [wherein a, b, c, and x are 78.0≦a≦82.0, 15.0≦b≦21.0, 0<c≦5.0, and 0.5≦x≦0.9] and containing impurities; a heat treatment step of charging the amorphous alloy powder into a continuous rotary kiln and heating at a temperature of 390°C or higher and 475°C or lower so that the space factor in the continuous rotary kiln is maintained within a range of 9% by volume or higher and 23% by volume or lower, thereby obtaining an amorphous alloy soft magnetic powder having a coercive force of 95.5 [A / m] or lower (1.2 [Oe] or lower) and an average particle size D50 of 3.0 μm or higher and 40.0 μm or lower; A method for producing an amorphous alloy soft magnetic powder, comprising:

2. 2. The method for producing an amorphous alloy soft magnetic powder according to claim 1, wherein the heat treatment time is from 15 minutes to 150 minutes.

3. 3. The method for producing an amorphous alloy soft magnetic powder according to claim 1, wherein the coercive force of the amorphous alloy soft magnetic powder is 39.8 [A / m] or more (0.5 [Oe] or more) and 79.6 [A / m] or less (1.0 [Oe] or less).

4. The amorphous alloy powder is a powder produced by a rotary water jet atomization method, 3. The method for producing an amorphous alloy soft magnetic powder according to claim 1, wherein the amorphous alloy soft magnetic powder has an average particle size D50 of 20.0 μm or more and 40.0 μm or less.

5. The pressure in the continuous rotary kiln during the heat treatment is 90 kPa or more and 110 kPa or less, 3. The method for producing an amorphous alloy soft magnetic powder according to claim 1, wherein the oxygen volume concentration in the continuous rotary kiln during the heat treatment is 100 ppm or more and 1500 ppm or less.

6. Composition formula expressed in atomic ratio: Fe ａ (Si １－ｘ B ｘ ) ｂ C ｃ [wherein a, b, c, and x are 78.0≦a≦82.0, 15.0≦b≦21.0, 0<c≦5.0, and 0.5≦x≦0.9] and impurities, The average particle size D50 is 3.0 μm or more and 40.0 μm or less, The coercive force is 95.5 [A / m] or less (1.2 [Oe] or less), When classified using a first sieve with a mesh size of 150 μm, the fraction that passes through the first sieve is designated as −150 particles, When the −150 particles are classified using a second sieve with a mesh size of 75 μm, the particles remaining on the second sieve are designated as +75 particles, and the particles passing through the second sieve are designated as −75 particles. When the −75 particles are classified using a third sieve having a mesh size of 53 μm, the particles remaining on the third sieve are designated as +53 particles, and the particles passing through the third sieve are designated as −53 particles. When the −53 particles are classified using a fourth sieve having a mesh size of 25 μm, the particles remaining on the fourth sieve are designated as +25 particles, and the particles passing through the fourth sieve are designated as −25 particles. Among the +75 particles having an average particle size D(+75), the +53 particles having an average particle size D(+53), the +25 particles having an average particle size D(+25), and the −25 particles having an average particle size D(−25), when the coercive force of the particles having an average particle size less than D50 is Hα and the coercive force of the particles having an average particle size of D50 or more is Hβ, Hα=γHβ (coefficient γ is 0.9 or more and 1.1 or less) The amorphous alloy soft magnetic powder satisfies the above requirements.

7. The maximum magnetization measured using a vibrating sample magnetometer is defined as Mm [emu / g]. True density is ρ [g / cm ３ ], 7. The amorphous alloy soft magnetic powder according to claim 6, wherein the saturation magnetic flux density Bs [T] calculated by 4π / 10000×ρ×Mm=Bs is 1.25 [T] or more and 1.85 [T] or less.

8. A dust core comprising the amorphous alloy soft magnetic powder according to claim 6 or 7.

9. A magnetic element comprising the powder magnetic core according to claim 8.

10. An electronic device comprising the magnetic element according to claim 9.

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