Producing method of amorphous alloy soft magnetic powder, amorphous alloy soft magnetic powder, powder magnetic core, magnetic element and electronic apparatus

Abstract

To provide amorphous alloy soft magnetic powder with low coercive force and a producing method of amorphous alloy soft magnetic powder capable of efficiently producing such amorphous alloy soft magnetic powder, a powder magnetic core and a magnetic element containing the amorphous alloy soft magnetic powder, and an electronic apparatus provided with the magnetic element.SOLUTION: A method for producing amorphous alloy soft magnetic powder, comprises a powder producing step of producing amorphous alloy powder having an average particle diameter of 3.0 μm or more and 40.0 μm or less, composed of a composition of Fe1-xCrx)a(Si1-yBy)100-a-bCb and impurities, and a heat treatment step of heating the amorphous alloy powder at a temperature of 400°C or higher and 540°C or lower, thereby producing amorphous alloy soft magnetic powder whose volume resistivity is 7.0×10-2 [Ω cm] or less when compacted under a pressure of 63.7 MPa.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 powder compact 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 100-a-b-c-d-e-f-g 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, and satisfy 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.] It contains amorphous metal particles having the composition represented by. 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 anisotropy (stress-induced anisotropy) introduced when manufacturing soft magnetic powder can be reduced. Thereby, low coercive magnetization can be achieved. Further, 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 viewpoint of further reducing the coercive force, there is still room for improvement in the manufacturing method of soft magnetic powder described in Patent Document 1. Therefore, there is a need to improve the manufacturing method so that the coercive force can be reliably reduced without impairing the manufacturing efficiency of the soft magnetic powder. [Means for solving the problem]

[0006] A method for producing an amorphous alloy soft magnetic powder according to an application example of the present invention includes the steps of: The composition formula expressed as the atomic ratio (Fe 1-x Cr x ) a (Si 1-y B y ) 100-a-b C b [x, y, a, b are 0 <x≦0.060、 0.30≦y≦0.70, 70.0≦a≦81.0, 0 <b≦3.0である。] a powder manufacturing process for manufacturing an amorphous alloy powder having an average particle size of 3.0 μm or more and 40.0 μm or less, the powder being composed of the above composition and impurities; By subjecting the amorphous alloy powder to a heat treatment at a temperature of 400°C or higher and 540°C or lower, the volume resistivity when compressed under a pressure of 63.7 MPa is reduced to 7.0 × 10 -2 a heat treatment process for producing amorphous alloy soft magnetic powder having a hardness of [Ω·cm] or less; It has.

[0007] The amorphous alloy soft magnetic powder according to the application example of the present invention has the following properties: The composition formula expressed as the atomic ratio (Fe 1-x Cr x ) a (Si 1-y B y ) 100-a-b C b [x, y, a, b are 0 <x≦0.060、 0.30≦y≦0.70, 70.0≦a≦81.0, 0 <b≦3.0である。] It is composed of the following composition and impurities: The average particle size is 3.0 μm or more and 40.0 μm or less, When compacted under a pressure of 63.7 MPa, the volume resistivity is 7.0 × 10 -2 [Ω·cm] or less.

[0008] A powder magnetic core according to an application example of the present invention includes: The present invention includes an amorphous alloy soft magnetic powder according to an application example thereof.

[0009] The magnetic element according to the application example of the present invention includes: The dust core according to the application example of the present invention is provided.

[0010] The electronic device according to the application example of the present invention includes: The magnetic element according to the application example of the present invention is provided. [Brief explanation of the drawings]

[0011] [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. 1 is a plan view schematically showing a toroidal type coil component. [Figure 3] FIG. 1 is a transparent perspective view schematically showing a closed magnetic circuit type coil component. [Figure 4] 1 is a perspective view showing a mobile personal computer as an electronic device according to an embodiment. [Figure 5] FIG. 1 is a plan view showing a smartphone as an electronic device according to an embodiment. [Figure 6] 1 is a perspective view showing a digital still camera as an electronic device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the manufacturing method of the amorphous alloy soft magnetic powder, the amorphous alloy soft magnetic powder, the compacted magnetic core, the magnetic element, and the electronic device of the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.

[0013] 1. Amorphous alloy soft magnetic powder First, the amorphous alloy soft magnetic powder according to the embodiment will be described.

[0014] The amorphous alloy soft magnetic powder can be applied to any use, and for example, it is used for the manufacture of a compacted magnetic core. The compacted magnetic core is manufactured by binding and molding the particles of the amorphous alloy soft magnetic powder.

[0015] The amorphous alloy soft magnetic powder according to the embodiment has a composition formula (Fe 1-x Cr x ) a (Si 1-y B y ) 100-a-b C b [where x, y, a, b satisfy 0 < x ≤ 0.060, 0.30 ≤ y ≤ 0.70, 70.0 ≤ a ≤ 81.0, 0 < b ≤ 3.0] and is composed of impurities.

[0016] Also, the amorphous alloy soft magnetic powder according to the embodiment has an average particle size of 3.0 μm or more and 40.0 μm or less.

[0017] Furthermore, the amorphous alloy soft magnetic powder according to the embodiment has a volume resistivity of 7.0×10 -2 [Ω·cm] or less when compacted under a pressure of 63.7 MPa.

[0018] By configuring the volume resistivity of the compact to be within the above range, a soft magnetic alloy powder with low coercivity can be obtained. Furthermore, when the volume resistivity of the compact is within the above range, the variation in the coercivity of the soft magnetic alloy powder can be suppressed. In other words, when the soft magnetic alloy powder configured so that the volume resistivity of the compact is within the above range is divided into multiple particle groups and the coercivity of each group is measured, the soft magnetic alloy powder has a homogeneity that minimizes the variation in the measured values. In other words, such a soft magnetic alloy powder can be said to be a powder in which each particle stably receives the effects of heat treatment and achieves low coercivity. Therefore, by manufacturing products such as powder magnetic cores using such soft magnetic alloy powder, products with stable characteristics can be manufactured with little individual variation.

[0019] 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 (Fe 1-x Cr x ) a (Si 1-y B y ) 100-a-b C b This composition formula represents the ratio of the number of atoms in a composition consisting of five elements: Fe, Cr, Si, B, and C.

[0020] Fe (iron) has a significant effect on the basic magnetic and mechanical properties of amorphous alloy soft magnetic powder.

[0021] Cr (chromium) acts to improve the corrosion resistance of amorphous alloy soft magnetic powder. Improved corrosion resistance suppresses oxidation of the particles, which in turn suppresses the deterioration of magnetic properties that accompanies oxidation. Furthermore, the passive film enhances the insulating properties of the particles, contributing to suppressing eddy current loss in magnetic elements.

[0022] x represents the ratio of the Cr content to the total content of the Fe content and the Cr content when the total of the Fe content and the Cr content is taken as 1. In the amorphous alloy soft magnetic powder, 0 < x ≤ 0.060, preferably 0.010 ≤ x ≤ 0.050, and more preferably 0.020 ≤ x ≤ 0.040.

[0023] a represents the ratio of the total of the Fe content and the Cr content. In the amorphous alloy soft magnetic powder, 70.0 ≤ a ≤ 81.0, preferably 73.0 ≤ a ≤ 80.0, and more preferably 75.0 ≤ a ≤ 77.0.

[0024] Si (silicon) promotes amorphization and increases the magnetic permeability of the amorphous alloy soft magnetic powder when manufacturing the amorphous alloy soft magnetic powder from raw materials. Thereby, it is possible to achieve high magnetic permeability and low coercive force.

[0025] B (boron) promotes amorphization when manufacturing the amorphous alloy soft magnetic powder from raw materials. In particular, by using Si and B in combination, based on the difference in the atomic radii of the two, amorphization can be synergistically promoted. Thereby, high magnetic permeability and low coercive force can be sufficiently achieved.

[0026] y represents the ratio of the B content to the total content of the Si content and the B content when the total of the Si content and the B content is taken as 1. In the amorphous alloy soft magnetic powder, 0.30 ≤ y ≤ 0.70, preferably 0.40 ≤ y ≤ 0.60.

[0027] The Si content ratio is preferably 8.0 atomic % or more and 13.5 atomic % or less, and more preferably 10.5 atomic % or more and 12.0 atomic % or less.

[0028] The B content ratio is preferably 8.0 atomic % or more and 13.5 atomic % or less, and more preferably 10.5 atomic % or more and 12.0 atomic % or less.

[0029] When melting the raw material of the amorphous alloy soft magnetic powder, carbon (C) reduces the viscosity of the melt, facilitating amorphization and micronization. As a result, amorphous alloy soft magnetic powder with a small diameter and high magnetic permeability can be obtained. Consequently, eddy current loss can be suppressed even in the high-frequency range.

[0030] b represents the C content. In the amorphous alloy soft magnetic powder, preferably 0 < b ≤ 3.0, more preferably 1.0 ≤ b ≤ 2.8, and still more preferably 1.5 ≤ b ≤ 2.5.

[0031] The amorphous alloy soft magnetic powder according to the embodiment may contain impurities in addition to the above elements. The impurities include all elements other than the above, but the total impurity content is preferably 0.50 atomic% or less. Within this range, even if impurities are mixed in, it is difficult to inhibit the above effects, so the inclusion is allowed.

[0032] Also, the content of each element contained in the impurities is preferably 0.10 atomic% or less. Within this range, it is difficult for the impurities to inhibit the above effects, so the inclusion is allowed.

[0033] Among the impurities, the oxygen content is particularly preferably 1500 ppm or less, more preferably 800 ppm or less, in terms of mass ratio. If the oxygen content is within the above range, the formation of oxides that cause a decrease in the density of the compact can be particularly reduced.

[0034] The soft magnetic alloy powder according to the embodiment has been described above. The above composition and impurities are specified by the following analysis methods.

[0035] Examples of analytical methods include iron and steel - atomic absorption spectrometry specified in JIS G 1257:2000, iron and steel - inductively coupled plasma (ICP) atomic emission spectrometry specified in JIS G 1258:2007, iron and steel - spark discharge atomic emission spectrometry specified in JIS G 1253:2002, iron and steel - X-ray fluorescence analysis specified in JIS G 1256:1997, and gravimetric / titration / absorptiometry specified in JIS G 1211 to G 1237.

[0036] Specific examples include a solid-state optical emission spectrometer manufactured by SPECTRO, in particular a spark discharge optical emission spectrometer, model: SPECTROLAB, type: LAVMB08A, and an ICP device, model CIROS120 manufactured by Rigaku Corporation.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 1.2.Powder characteristics The average particle size of the amorphous alloy soft magnetic powder is 3.0 μm or more and 40.0 μm or less, preferably 10.0 μm or more and 35.0 μm or less, and more preferably 20.0 μm or more and 30.0 μm or less. Such amorphous alloy soft magnetic powder is prevented from crystallizing by heat treatment and stress distortion is sufficiently alleviated. This makes it easier to achieve low coercive force. Furthermore, the relatively small average particle size contributes to the realization of magnetic elements with low eddy current loss.

[0041] Furthermore, when the average particle size is set to 20.0 μm or more, 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 within this range is mixed with other soft magnetic powders having smaller particle sizes 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 within this range have a high degree of amorphization even when they are large in diameter, they contribute to the realization of magnetic elements with high magnetic permeability and low coercivity.

[0042] The average particle size of the amorphous alloy soft magnetic powder is determined as the particle size D50 at which the cumulative 50% from the smallest diameter side is reached in the volume-based particle size distribution obtained by laser diffraction.

[0043] Furthermore, if the average particle size 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 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 the stress-strain relaxation due to heat treatment may be insufficient, making it difficult to achieve a low coercive force.

[0044] 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 1.5 or more and 2.5 or less. (D90-D10) / D50 is an index indicating the degree of spread of the particle size distribution, and when this index is 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.

[0045] 1.3.Magnetic Properties The coercive force of the amorphous alloy soft magnetic powder according to the embodiment is preferably 79.6 [A / m] or less (1.0 [Oe] or less), more preferably 15.9 [A / m] or more (0.2 [Oe] or more) and 71.6 [A / m] or less (0.9 [Oe] or less), and even more preferably 23.9 [A / m] or more (0.3 [Oe] or more) and 63.7 [A / m] or less (0.8 [Oe] or less).

[0046] By using such amorphous alloy soft magnetic powder with particularly low coercive force, it is possible to manufacture a magnetic element capable of sufficiently suppressing hysteresis loss.

[0047] If the coercive force is below the lower limit, it becomes difficult to stably produce such low-coercive 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, and the iron loss of the powder magnetic core may become large.

[0048] 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.

[0049] The amorphous alloy soft magnetic powder according to the embodiment preferably has a magnetic permeability of 18.0 or more, more preferably 20.0 or more, at a measurement frequency of 100 kHz. Such amorphous alloy soft magnetic powders are resistant to magnetic flux saturation even when subjected to a strong magnetic field, contributing to the realization of powder magnetic cores with high saturation magnetic flux densities and small powder magnetic cores. The upper limit of the magnetic permeability is not particularly limited, but is set to 50.0 or less, taking into consideration stable production.

[0050] The magnetic permeability of the amorphous alloy soft magnetic powder is measured on a toroidal green compact produced using the amorphous alloy soft magnetic powder. Specifically, the amorphous alloy soft magnetic powder is mixed with an epoxy resin in an amount equivalent to 2.0 mass % of the green compact, and the resulting mixture is subjected to a pressure of 294.2 MPa (3 t / cm). 2 ) to obtain a ring-shaped green compact with an outer diameter of 14 mm, an inner diameter of 8 mm, and a thickness of 3 mm. A conductor with a wire diameter of 0.6 mm is then wound around the green compact seven times, and the magnetic permeability is measured.

[0051] 2. Manufacturing method of amorphous alloy soft magnetic powder Next, a method for producing the amorphous alloy soft magnetic powder according to the embodiment will be described.

[0052] FIG. 1 is a process diagram showing the configuration of a method for producing an amorphous alloy soft magnetic powder according to an embodiment.

[0053] The method for producing the amorphous alloy soft magnetic powder shown in FIG. 1 includes a powder production step S102 and a heat treatment step S104.

[0054] 2.1. Powder manufacturing process In the powder production step S102, powder (amorphous alloy powder) before heat treatment is produced.

[0055] Amorphous alloy powder is a material with a composition formula expressed in atomic ratio (Fe 1-x Cr x ) a (Si 1-y By ) 100-a-b C b [x, y, a, and b are such that 0 < x ≤ 0.060, 0.30 ≤ y ≤ 0.70, 70.0 ≤ a ≤ 81.0, and 0 < b ≤ 3.0.] It is a powder composed of an amorphous alloy composed of composition and impurities. The average particle size of the amorphous alloy powder is 3.0 μm or more and 40.0 μm or less.

[0056] Such amorphous alloy powder may have stress strain during the manufacturing process or the like. Therefore, by subjecting the amorphous alloy powder to the heat treatment described below, the stress strain is relaxed to achieve low coercivity magnetization.

[0057] The crystallinity of each particle of the amorphous alloy powder is less than 50%, preferably 30% or less. The crystallinity is obtained by acquiring an X-ray diffraction spectrum for the amorphous alloy powder and calculated based on the following formula. Crystallinity = {Intensity derived from crystal / (Intensity derived from crystal + Intensity derived from amorphous)} × 100

[0058] The amorphous alloy powder may be manufactured by any manufacturing method. For example, in addition to atomization methods such as water atomization method, gas atomization method, and rotating water flow atomization method, it is manufactured by various powdering methods such as reduction method, carbonyl method, and pulverization method.

[0059] The atomization method is a method of producing powder by colliding molten raw material with a fluid such as a liquid or gas jetted at a high speed, thereby pulverizing and cooling it. Depending on the type of cooling medium and the difference in apparatus configuration, the atomization method includes the water atomization method, gas atomization method, rotating water flow atomization method, etc. Among these, the amorphous alloy powder is preferably manufactured by the water atomization method or the rotating water flow atomization method, and more preferably manufactured by the rotating water flow atomization method.

[0060] In this specification, the term "water atomization" refers to a method of producing metal powder by using a liquid such as water or oil 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 this convergence point.

[0061] On the other hand, the "rotary water jet atomization method" in this specification is a method in which a coolant is jetted and supplied along the inner circumferential surface of a cooling cylinder and rotated to form a coolant layer on the inner circumferential surface, and molten metal, formed by melting the raw material of amorphous alloy powder, is splashed and brought into contact with this coolant layer. The finely powdered molten metal is taken into the coolant layer and is rapidly cooled and solidified. This produces amorphous alloy powder.

[0062] In the rotary water jet atomization method, a continuous supply of cooling liquid allows an extremely high cooling rate to be stably maintained, which promotes the amorphization of the produced amorphous alloy powder even when the particle size is large.

[0063] 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.

[0064] The average particle size of the amorphous alloy powder is 3.0 μm or more and 40.0 μm or less, preferably 10.0 μm or more and 35.0 μm or less, and more preferably 20.0 μm or more and 30.0 μm or less. Such amorphous alloy powder is prevented from crystallizing by heat treatment and stress distortion is sufficiently alleviated. This makes it easier to achieve low coercive force. Furthermore, the relatively small average particle size contributes to the realization of magnetic elements with low eddy current loss.

[0065] In particular, when the average particle size of the amorphous alloy powder is 20.0 μm or more, the obtained amorphous alloy soft magnetic powder is suitable for use in combination with other soft magnetic powders having smaller average particle sizes.

[0066] 2.2.Heat treatment process In the heat treatment step S104, the amorphous alloy powder is subjected to a heat treatment at a temperature of 400° C. to 540° C. This can relieve the stress strain of the amorphous alloy powder, and an amorphous alloy soft magnetic powder with low coercive force can be obtained.

[0067] The heat treatment in this process is carried out so that the volume resistivity of the green compact made from the amorphous alloy soft magnetic powder becomes 7.0 × 10 -2 The temperature and other conditions are set so that the volume resistivity is below [Ω·cm]. This reduces variation in the coercivity of the manufactured amorphous alloy soft magnetic powder. The reason for this effect is thought to be that when the volume resistivity is within the above range, stress strain in the atomic arrangement is easily alleviated. In other words, when the volume resistivity of the amorphous alloy soft magnetic powder is within the above range, even if the temperature and time of the heat treatment vary from particle to particle, it is thought that this does not affect the progress of the heat treatment. This results in a more uniform heat treatment, resulting in a lower coercivity for the amorphous alloy soft magnetic powder as a whole. Furthermore, because defective particles due to insufficient or excessive heat are less likely to occur, amorphous alloy soft magnetic powder with a specified coercivity and consistent quality can be efficiently manufactured.

[0068] The volume resistivity of the green compact is preferably 3.0×10 -2 [Ω·cm] or less, and more preferably 2.5×10 -2 On the other hand, from the viewpoint of reducing the difficulty of manufacturing and increasing the manufacturing yield, the lower limit of the volume resistivity of the green compact is preferably 0.1 × 10 -2 [Ω·cm] or more, and more preferably 0.5×10 -2 [Ω·cm] or more.

[0069] The volume resistivity of the powder compact was measured as follows. First, 7.0 g of amorphous alloy soft magnetic powder was placed in the sample container of the powder resistivity measurement probe unit. The inner radius of the sample container was 10.0 mm. The electrodes attached to the sample container had a radius of 0.7 mm, an electrode spacing of 3.0 mm, and a four-point probe. Next, the sample was gradually pressurized using the hydraulic pump attached to the unit to produce a cylindrical green compact with a mass of 7.0 g. While applying a pressure of 63.7 MPa to the green compact, the volume resistivity of the green compact was measured using a resistivity meter connected to the unit. The powder resistivity measurement probe unit used was a powder resistance measurement system manufactured by Nitto Seiko Analytech Co., Ltd. The resistivity meter used was a low resistivity meter, Loresta GP, manufactured by Nitto Seiko Analytech Co., Ltd.

[0070] The heat treatment temperature is set to 400°C or higher and 540°C or lower, preferably 410°C or higher and 530°C or lower, and more preferably 420°C or higher and 520°C or lower. If the heat treatment temperature is within this range, the volume resistivity of the green compact can be set within the above range. This makes it possible to sufficiently alleviate stress strain while suppressing crystallization of the amorphous alloy powder.

[0071] If the heat treatment temperature is below the lower limit, the stress strain cannot be sufficiently alleviated during the heat treatment, resulting in an increased coercive force, whereas if the heat treatment temperature is above the upper limit, the amorphous alloy powder may crystallize.

[0072] The time for maintaining the above temperature during the heat treatment (heat treatment time) is preferably 5 minutes to 60 minutes, more preferably 7 minutes to 45 minutes, and even more preferably 10 minutes to 30 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.

[0073] 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.

[0074] The heat treatment is performed, for example, using a heat treatment furnace. The pressure inside the heat treatment furnace may be atmospheric pressure, negative pressure, or positive pressure. Of these, positive pressure is preferable. By performing heat treatment under positive pressure inside the heat treatment furnace, the thermal conductivity around the amorphous alloy powder can be increased within the heat treatment furnace. This allows the amorphous alloy powder to be heated evenly throughout, resulting in amorphous alloy soft magnetic powder with reduced volume resistivity when compacted. As a result, the coercivity of the amorphous alloy soft magnetic powder as a whole can be further reduced. Furthermore, when positive pressure is achieved by introducing gas, the internal atmosphere tends to be constant. As a result, for example, when positive pressure is achieved while introducing an inert gas, the concentration of the inert gas tends to be uniform, making it easier to suppress unintended oxidation of the amorphous alloy powder.

[0075] The pressure in the heat treatment furnace is preferably 5 Pa or more and 1000 Pa or less, more preferably 10 Pa or more and 700 Pa or less, and even more preferably 50 Pa or more and 500 Pa or less. If the pressure in the heat treatment furnace is within the above range, the coercivity of the amorphous alloy soft magnetic powder as a whole can be further reduced. In particular, gas exists in the narrow space between the particles of the amorphous alloy powder, and this mediates heat conduction while being affected by the interparticle distance. Therefore, it is believed that the thermal conductivity between particles is easily affected by pressure.

[0076] If the pressure in the heat treatment furnace is below the lower limit, the temperature and other parameters during the heat treatment tend to vary from particle to particle, potentially resulting in insufficient or excessive heat treatment in some areas. On the other hand, if the pressure in the heat treatment furnace exceeds the upper limit, no further effect can be expected, potentially resulting in a decrease in the energy efficiency of the heat treatment. Furthermore, the gas flow rate in the heat treatment furnace tends to increase locally, potentially resulting in an uneven temperature distribution.

[0077] For example, a positive pressure of 10 Pa is a pressure that is 10 Pa higher than atmospheric pressure, and if the atmospheric pressure is 101.3 kPa, for example, this refers to 101.31 kPa.

[0078] The atmosphere in the heat treatment furnace is not particularly limited, and may be an acidic atmosphere, a reducing atmosphere, or the like. However, an inert atmosphere is preferred, with an oxygen volume concentration of 1500 ppm or less being more preferred, an oxygen volume concentration of 200 ppm to 1000 ppm being even more preferred, and an oxygen volume concentration of 300 ppm to 700 ppm being particularly preferred. When the oxygen volume concentration of the inert atmosphere is within the above range, oxidation of the amorphous alloy powder can be more reliably suppressed. This prevents the formation of an oxide film on the particle surface and prevents the volume resistivity of the compact from increasing. Furthermore, the formation of an oxide film may make it difficult to relax stress-strain. Taking this into consideration, when the oxygen volume concentration is within the above range, the coercivity of the amorphous alloy powder can be effectively reduced by heat treatment.

[0079] Examples of the inert gas that constitutes the inert atmosphere include nitrogen gas and argon gas.

[0080] 3. Powder cores and magnetic elements Next, the powder magnetic core and the magnetic element according to the embodiment will be described.

[0081] Two types of coil components will be described below as representative examples of the magnetic element according to the embodiment. 3.1.Toroidal type FIG. 2 is a plan view schematically showing a toroidal-type coil component 10. The coil component 10 shown in FIG. 2 has a ring-shaped powder magnetic core 11 and a conductive wire 12 wound around this powder magnetic core 11. The powder magnetic core 11 (the powder magnetic core according to the embodiment) contains the amorphous alloy soft magnetic powder described above. This results in a powder magnetic core 11 with low coercivity. As a result, a coil component 10 with low iron loss is obtained. Such a coil component 10 contributes to power saving in electronic devices.

[0082] The shape of the powder magnetic core 11 is not limited to the ring shape shown in FIG. 2, but may be, for example, a shape in which a part of the ring is missing, a shape in which the longitudinal direction is linear, a sheet shape, a film shape, or the like.

[0083] 3.2.Closed magnetic circuit type FIG. 3 is a see-through perspective view that schematically shows a coil component 20 of a closed magnetic circuit type.

[0084] The closed magnetic circuit type coil component 20 will be described below, but the following description will focus on the differences from the coil component 10, and a description of similar points will be omitted.

[0085] The coil component 20 shown in FIG. 3 is formed by embedding a conductor wire 22 formed into a coil shape inside a powder magnetic core 21. The powder magnetic core 21 (the powder magnetic core according to the embodiment) contains the amorphous alloy soft magnetic powder described above. This results in a powder magnetic core 21 with low coercivity. As a result, a coil component 20 with low iron loss is obtained. Such a coil component 20 contributes to power saving in electronic devices.

[0086] The shape of the powder magnetic core 21 is not limited to the shape shown in FIG. 3, but may be a sheet, a film, or the like.

[0087] Furthermore, the magnetic element is not limited to the above-mentioned coil component, but may be, for example, a choke coil, an inductor, a noise filter, a reactor, a transformer, a motor, an actuator, a solenoid valve, a generator, or the like.

[0088] 4.Electronic equipment Next, an electronic device including the magnetic element according to the embodiment will be described with reference to FIGS.

[0089] Fig. 4 is a perspective view showing a mobile personal computer 1100, which is an electronic device according to an embodiment. The personal computer 1100 shown in Fig. 4 includes a main body 1104 having a keyboard 1102, and a display unit 1106 having 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.

[0090] Fig. 5 is a plan view showing a smartphone 1200, which is an electronic device according to an embodiment. The smartphone 1200 shown in Fig. 5 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 built-in magnetic element 1000, such as an inductor, a noise filter, or a motor.

[0091] 6 is a perspective view showing a digital still camera 1300, which is an electronic device according to an 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.

[0092] 6 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., on the back side in the figure.

[0093] 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.

[0094] The above-described powder magnetic core 11 or powder magnetic core 21 is used in these magnetic elements 1000. This contributes to power saving of electronic devices.

[0095] Examples of electronic devices according to the embodiments include the personal computer 1100 of FIG. 4, the smartphone 1200 of FIG. 5, and the digital still camera 1300 of FIG. 6, 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.

[0096] 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 1-x Cr x ) a (Si 1-y B y ) 100-a-b C b[x, y, a, and b satisfy 0 < x ≤ 0.060, 0.30 ≤ y ≤ 0.70, 70.0 ≤ a ≤ 81.0, and 0 < b ≤ 3.0.] Produce an amorphous alloy powder composed of such a composition and impurities, with an average particle size of 3.0 μm or more and 40.0 μm or less. In the heat treatment step S104, perform a heat treatment by heating the amorphous alloy powder at a temperature of 400°C or more and 540°C or less, thereby obtaining an amorphous alloy soft magnetic powder with a volume resistivity of 7.0×10 -2 [Ω·cm] or less when compacted under a pressure of 63.7 MPa.

[0097] 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 a low coercive force can be efficiently produced. Further, an amorphous alloy soft magnetic powder with little variation in coercive force and stable quality can be obtained.

[0098] In the method for producing an amorphous alloy soft magnetic powder according to the above embodiment, the heat treatment time is 5 minutes or more and 60 minutes or less.

[0099] According to such a configuration, while suppressing the crystallization of the amorphous alloy powder, the stress strain can be sufficiently relaxed.

[0100] 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 79.6 [A / m] or less (1.0 [Oe] or less).

[0101] According to such a configuration, an amorphous alloy soft magnetic powder can be obtained that has a particularly low coercive force and can be used to manufacture a magnetic element with sufficiently suppressed hysteresis loss.

[0102] In the method for producing an amorphous alloy soft magnetic powder according to the above embodiment, the heat treatment is performed under a positive pressure of 5 Pa or more and 1000 Pa or less.

[0103] This configuration allows the amorphous alloy soft magnetic powder to have a lower overall coercivity. Furthermore, during heat treatment, gas exists in the narrow spaces between the particles of the amorphous alloy powder, and this gas mediates heat conduction while being affected by the interparticle distance. Therefore, it is believed that the thermal conductivity between particles is easily affected by pressure. Therefore, by performing heat treatment under the above pressure, temperature variations during heat treatment can be suppressed.

[0104] In the method for producing the amorphous alloy soft magnetic powder according to the embodiment, the heat treatment is carried out in an inert atmosphere with an oxygen volume concentration of 1500 ppm or less.

[0105] This configuration can more reliably suppress oxidation of the amorphous alloy powder, and also suppress the formation of oxide films on the particle surfaces, thereby suppressing the stress-strain relaxation from becoming difficult.

[0106] In the method for producing amorphous alloy soft magnetic powder according to the embodiment, the powder production step S102 includes an operation of producing amorphous alloy powder having an average particle size of 20 μm or more and 40 μm or less by a rotary water jet atomization method, and the heat treatment step S104 is performed under a positive pressure of 10 Pa or more and 700 Pa or less.

[0107] This configuration provides an amorphous alloy soft magnetic powder suitable for use in combination with other soft magnetic powders, which contributes to further increasing the density of the powder core and further reducing the coercive force of the amorphous alloy soft magnetic powder as a whole.

[0108] The amorphous alloy soft magnetic powder according to the embodiment has a composition formula (Fe 1-x Cr x ) a (Si 1-y B y ) 100-a-b C b[x, y, a, and b satisfy 0 < x ≤ 0.060, 0.30 ≤ y ≤ 0.70, 70.0 ≤ a ≤ 81.0, and 0 < b ≤ 3.0.] It is composed of composition and impurities and has an average particle size of 3.0 μm or more and 40.0 μm or less. And the amorphous alloy soft magnetic powder according to the above embodiment has a volume resistivity of 7.0×10 -2 [Ω·cm] or less when compacted under a pressure of 63.7 MPa. According to such a configuration, an amorphous alloy soft magnetic powder with a low coercive force can be obtained.

[0109] In the amorphous alloy soft magnetic powder according to the above embodiment, the coercive force is 79.6 [A / m] or less (1.0 [Oe] or less).

[0110] According to such a configuration, an amorphous alloy soft magnetic powder capable of manufacturing a magnetic element that can sufficiently suppress hysteresis loss can be obtained.

[0111] The compacted magnetic core according to the above embodiment contains the amorphous alloy soft magnetic powder according to the above embodiment. <000047�>According to such a configuration, a compacted magnetic core with a low coercive force and low iron loss can be obtained.

[0112] The magnetic element according to the above embodiment includes the compacted magnetic core according to the above embodiment. ​​​​​​​​​​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.

[0115] 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.

[0116] 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]

[0117] Next, specific examples of the present invention will be described. 6. Manufacturing of powder magnetic cores 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, which was then classified using a sieve classifier.

[0118] Next, the classified amorphous alloy powder was subjected to heat treatment under the conditions shown in Table 1. As a result, an amorphous alloy soft magnetic powder was obtained. The composition of the obtained amorphous alloy soft magnetic powder is shown in Table 1. The composition was determined using a solid-state optical emission spectrometer manufactured by SPECTRO, model: SPECTROLAB, type: LAVMB08A.

[0119] 6.2. Samples No. 2 to 22 An amorphous alloy soft magnetic powder was obtained in the same manner as Sample No. 1, except that the raw materials were changed to obtain the composition shown in Table 1 or Table 2, and the powder manufacturing method and heat treatment conditions shown in Table 1 or Table 2 were adopted.

[0120] 7. Characteristics of amorphous alloy soft magnetic powder 7.1.Representative particle size The amorphous alloy soft magnetic powder of each sample number was subjected to particle size distribution measurement to obtain the representative particle size. This measurement was performed using a laser diffraction particle size distribution measuring device, Microtrac HRA9320-X100 manufactured by Nikkiso Co., Ltd. Then, D10, D50, D90, and (D90-D10) / D50 were calculated. The calculation results are shown in Tables 3 and 4.

[0121] 7.2.Volume Resistivity of Powder Compacts The volume resistivity of the green compact was measured for each amorphous alloy soft magnetic powder sample No. The measurement results are shown in Tables 3 and 4.

[0122] In Tables 1 to 4, the amorphous alloy soft magnetic powders and their manufacturing methods for each sample number that correspond to the present invention are indicated as "Examples," and those that do not correspond to the present invention are indicated as "Comparative Examples."

[0123] [Table 1]

[0124] [Table 2]

[0125] 8. Evaluation of amorphous alloy soft magnetic powder 8.1. Coercive force of amorphous alloy soft magnetic powder The coercive force of the amorphous alloy soft magnetic powders of each example and comparative example was measured, and the measurement results are shown in Tables 3 and 4.

[0126] 8.2. Variation in coercive force of amorphous alloy soft magnetic powder The amorphous alloy soft magnetic powders of each example and comparative example were evaluated for variation in coercive force by the following method. The evaluation results are shown in Tables 3 and 4.

[0127] First, 5 g of amorphous alloy soft magnetic powder was prepared and divided into 10 equal parts. Next, the coercive force of each of the equal parts was measured, and the range of the measured values ​​(the difference between the maximum and minimum values) was calculated. The calculated results were then evaluated in accordance with the following evaluation criteria.

[0128] A: The measurement range is particularly small B: The range of measured values ​​is somewhat large, but this does not pose a practical problem. C: The range of measured values ​​is large, which hinders practical use.

[0129] 9. Evaluation of magnetic elements The amorphous alloy soft magnetic powder of each example and comparative example was mixed with an epoxy resin binder and toluene as an organic solvent to obtain a mixture. The amount of epoxy resin added was 2 parts by mass per 100 parts by mass of the amorphous alloy soft magnetic powder.

[0130] The resulting mixture was then stirred and dried for a short time to obtain a dried mass. The dried mass was then sieved through a 400 μm mesh sieve and pulverized to obtain a granulated powder. The resulting granulated powder was dried at 50° C. for 1 hour.

[0131] Next, the obtained granulated powder was filled into a molding die, and a dust core was obtained based on the following molding conditions.

[0132] Molding method: Press molding Shape of molding: Ring-shaped - Dimensions of the molded body: outer diameter 14mm, inner diameter 8mm, thickness 3mm Molding pressure: 0.5t / cm 2 (49MPa) ·Molding temperature: 70℃

[0133] Next, a magnetic element was produced using the obtained powder magnetic core under the following production conditions.

[0134] Conductor material: Cu Conductor diameter: 0.16mm Number of turns: 18 turns on the primary side, 18 turns on the secondary side

[0135] Next, the iron loss of the fabricated magnetic element was measured under the following measurement conditions.

[0136] Measurement equipment: Iwasaki Electric Co., Ltd., BH analyzer SY-8218 Measurement frequency: 1MHz Maximum magnetic flux density: 20mT

[0137] The measured iron loss was then evaluated based on the following evaluation criteria. The evaluation results are shown in Tables 3 and 4.

[0138] A: Low iron loss (iron loss is 800kW / m 3 (The following is true: B: Iron loss is slightly small (iron loss is 800kW / m 3 Super 1000kW / m 3 (The following is true: C: Large iron loss (iron loss is 1000kW / m 3 (less than or equal to)

[0139] [Table 3]

[0140] [Table 4]

[0141] As shown in Tables 3 and 4, the amorphous alloy soft magnetic powders obtained in each Example were found to have lower coercive force than the amorphous alloy soft magnetic powders obtained in each Comparative Example. In addition, the variation in coercive force was also kept small. [Explanation of symbols]

[0142] 10...coil component, 11...powder magnetic core, 12...conductor, 20...coil component, 21...powder magnetic core, 22...conductor, 100...display unit, 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, S102...powder manufacturing process, S104...heat treatment process

Claims

1. Composition formula expressed by atomic ratio (Fe １－ｘ Cr ｘ ) ａ (Si １－ｙ B ｙ ) １００－ａ－ｂ C ｂ [x, y, a, b are 0<x≦0.060, 0.30≦y≦0.70, 70.0≦a≦81.0, 0<b≦3.0.] a powder production process for producing an amorphous alloy powder having an average particle size of 3.0 μm or more and 40.0 μm or less, the powder being composed of the above composition and impurities; The amorphous alloy powder is subjected to a heat treatment at a temperature of 400° C. or higher and 540° C. or lower, and when compacted under a pressure of 63.7 MPa, the volume resistivity is 7.0×10 －２ a heat treatment step for producing an amorphous alloy soft magnetic powder having a hardness of [Ω cm] or less; 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 5 minutes to 60 minutes.

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

4. 3. The method for producing an amorphous alloy soft magnetic powder according to claim 1, wherein the heat treatment is carried out under a positive pressure of 5 Pa or more and 1000 Pa or less.

5. 3. The method for producing amorphous alloy soft magnetic powder according to claim 1, wherein the heat treatment is carried out in an inert atmosphere having an oxygen volume concentration of 1500 ppm or less.

6. the powder production step includes an operation of producing the amorphous alloy powder having an average particle size of 20 μm or more and 40 μm or less by a rotary water jet atomization method, 3. The method for producing an amorphous alloy soft magnetic powder according to claim 1, wherein the heat treatment step is performed under a positive pressure of 10 Pa or more and 700 Pa or less.

7. Composition formula expressed by atomic ratio (Fe １－ｘ Cr ｘ ) ａ (Si １－ｙ B ｙ ) １００－ａ－ｂ C ｂ [x, y, a, b are 0<x≦0.060, 0.30≦y≦0.70, 70.0≦a≦81.0, 0<b≦3.0.] It is composed of the following composition and impurities: The average particle size is 3.0 μm or more and 40.0 μm or less, The volume resistivity when compressed at a pressure of 63.7 MPa is 7.0 × 10 －２ The amorphous alloy soft magnetic powder has a resistivity of Ω·cm or less.

8. 8. The amorphous alloy soft magnetic powder according to claim 7, which has a coercive force of 79.6 [A / m] or less (1.0 [Oe] or less).

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

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

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

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