JP2009188270A - Soft magnetic particle powder, manufacturing method thereof, and powder magnetic core containing the powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soft magnetic particle powder having an insulating layer excellent in thermal resistance, to provide a manufacturing method thereof capable of forming a uniform insulating layer excellent in adhesiveness to the soft magnetic metal particle surface, and to provide a powder magnetic core whose specific resistance hardly decreases even if the magnetic core containing the powder is sintered at a high temperature. <P>SOLUTION: The soft magnetic metal particle powder having the insulating layer, composed of one or two or more oxide microparticles selected from aluminum, silicon, magnesium, titanium, zirconium, yttrium and calcium oxides, on the particle surface is obtained by premixing the soft magnetic metal particle powder with the oxide microparticles, and thereafter, acting a mechanical energy composed of a compression/shearing force to form the insulation layer on the particle surface of the soft magnetic metal particle powder. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a soft magnetic particle powder having an insulating layer having excellent heat resistance, a method for producing a soft magnetic particle powder capable of forming a uniform insulating layer having excellent adhesion to the surface of soft magnetic metal particles, and the soft magnetic particle powder. Provided is a dust core in which specific resistance is less likely to decrease even when fired at a high temperature containing magnetic particle powder.

  In recent years, along with energy saving and miniaturization of home appliances and electronic devices, there is an increasing demand for miniaturization, high output, and high efficiency of power conversion efficiency for magnetic core materials used for these. Higher operating frequency is known to be effective in reducing the size of equipment, increasing output, and increasing power conversion efficiency. Even in the high frequency range, high magnetic flux density, magnetic permeability, and low iron loss. There is a strong need for magnetic core materials.

  Conventionally, as such a magnetic core material, a laminated magnetic core using a silicon steel plate or the like has been used. However, a laminated magnetic core has a disadvantage that eddy current loss generated inside the magnetic core increases as the operating frequency increases. have.

  For this reason, in recent years, a powder core in which a soft magnetic powder is coated with an insulating resin such as a phenol resin or an epoxy resin and is compression-molded has a low iron loss in a high frequency region as compared with a laminated magnetic core and has excellent moldability. However, it is widely used as a substitute for a laminated magnetic core.

  On the other hand, further miniaturization and higher performance, that is, higher magnetic flux density is desired for the powder magnetic core. For such higher magnetic flux density, the packing density of the soft magnetic powder is increased. Things have been done.

  However, it is known that since compression molding is performed at a high pressure in order to highly fill the soft magnetic powder, strain remains in the soft magnetic powder, leading to an increase in hysteresis loss. Therefore, in order to reduce the hysteresis loss due to strain, the molded product is usually annealed.

  By the way, in general, hysteresis loss and eddy current loss are known as main causes of iron loss of a dust core. As described above, it is known that the removal of strain due to annealing is effective as a method for reducing hysteresis loss. On the other hand, as a method for reducing eddy current loss, an insulating resin or the like is used between particles. It is done by insulating.

  However, annealing is generally effective at a temperature of 500 ° C. or higher, preferably 600 ° C. or higher. However, the bonding resin as a binder of the soft magnetic particle powder and the insulation between the particles are not effective. For this reason, when an insulating resin is used, annealing at a high temperature causes the resin to decompose and the molded body to become brittle, resulting in a decrease in insulation. It was difficult to reduce both loss and eddy current loss at the same time.

So far, after firmly fixing the iron oxide and insulating material formed on the surface of soft magnetic metal powder such as iron powder for the purpose of obtaining soft magnetic metal powder having insulating coating with excellent heat resistance Furthermore, a soft magnetic metal powder further coated with a silicone resin (Patent Document 1) is disclosed.

In addition, for the purpose of increasing the space factor of the soft magnetic powder and improving the magnetic flux density, soft magnetic powder particles in which an insulating layer made of an inorganic material containing no resin is formed on the surface of soft magnetic metal particles such as iron powder ( Patent Document 2) is disclosed.

In addition, for the purpose of preventing exfoliation of high-resistance substances coated on the surface of soft magnetic metal powder such as iron powder, a soft magnetic material in which a phosphate conversion coating is further formed on the surface of the high-resistance substance coated on the surface of soft magnetic metal particles Particles (Patent Document 3) are disclosed.

  In addition, for the purpose of forming a uniform insulating layer on the surface of the soft magnetic metal powder such as iron powder, an oxide sol is attached to the surface of the soft magnetic metal powder in an aqueous solution (Patent Document 4), or a metal alkoxide is added. Hydromagnetic metal powder that is hydrolyzed to adsorb hydroxide on the surface of the soft magnetic metal powder (Patent Document 5), or a compound such as silicon is directly deposited on the surface of the soft magnetic metal powder in an aqueous solution (Patent Document 6) ) Is disclosed.

  In addition, for the purpose of forming an insulating layer made of a fine inorganic compound on the surface of soft magnetic metal powder such as iron powder, the surface of soft magnetic metal powder is hydrolyzed with metal alkoxide in an organic solvent to form soft magnetic metal powder. A soft magnetic metal powder (Patent Document 7) having an inorganic compound attached to the surface is disclosed.

JP 2006-233295 A JP 2003-332116 A JP 2001-85211 A JP-A-9-180924 JP 2007-129154 A JP 2006-291260 A JP 2005-206880 A

  A soft magnetic particle powder having an insulating layer excellent in heat resistance is currently most demanded, but has not yet been obtained.

  That is, in Patent Document 1, it is described that the iron oxide formed on the surface of the soft magnetic metal powder and the insulating substance are firmly fixed and then further coated with a silicone resin. As a result, the specific gravity of the soft magnetic metal powder is reduced, and the green compact obtained using the powder also has a problem that the density is lowered, and as a result, a sufficient magnetic flux density cannot be obtained.

  Patent Document 2 describes that the surface of soft magnetic metal particles and oxide powder are mixed to form an insulating layer. The particle size of the oxide powder forming the insulating layer is 0.1 to 0.1. Since it is as large as 10 μm and a uniform insulating coating cannot be formed on the surface of the soft magnetic metal particles, it is difficult to obtain sufficient heat resistance.

  Patent Document 3 describes that the surface of a high-resistance substance coated on the surface of soft magnetic metal particles such as iron powder is further treated with a phosphoric acid chemical conversion treatment solution to form two insulating layers. However, since the phosphoric acid-based chemical conversion coating film changes in quality at a high temperature, there is a problem that heat treatment cannot be performed at a temperature of 600 ° C. or higher.

  Patent Documents 4 to 6 describe that the insulating layer is formed on the surface of the soft magnetic metal powder in an aqueous solution. However, the soft magnetic metal powder is easily oxidized and corroded by moisture, and the magnetic properties are deteriorated. At the same time, since the oxide film becomes thick, when the powder magnetic core is formed using the oxide film, the ratio of the soft magnetic metal powder in the powder magnetic core is reduced, so that it is difficult to increase the magnetic flux density.

  Patent Document 7 describes that an insulating layer is formed on the surface of a soft magnetic metal powder in an organic solvent, but the organic solvent contains about 0.5 to 5% of water. As described above, the soft magnetic metal powder is easily oxidized and corroded by moisture, and its magnetic properties are deteriorated and the oxide film becomes thick. Therefore, when the powder magnetic core is formed using this, the soft magnetic metal powder is soft in the powder magnetic core. Since the proportion of the magnetic metal powder decreases, it is difficult to increase the magnetic flux density.

  Therefore, the present invention has a technical problem to obtain a soft magnetic particle powder having an insulating layer excellent in heat resistance.

  As a result of intensive studies to solve the above problems, the inventors of the present invention are soft magnetic metal particle powders having an insulating layer on the particle surface, and the insulating layer has an average particle diameter of less than 100 nm, aluminum, The soft magnetic particle powder composed of one or more oxide fine particles selected from silicon, magnesium, titanium, zirconium, yttrium, and calcium has excellent heat resistance, and the soft magnetic particle powder is used as a dust core. It has been found that a powder magnetic core in which the specific resistance is hardly lowered even when baked at a high temperature can be obtained by using it as a soft magnetic material.

  That is, the present invention is a soft magnetic metal particle powder having an insulating layer on the particle surface, wherein the insulating layer is one or more selected from aluminum, silicon, magnesium, titanium, zirconium, yttrium, and calcium. A soft magnetic particle powder characterized by comprising fine oxide particles (Invention 1).

  Further, the present invention is the soft magnetic particle powder of the present invention 1 wherein the fine oxide particles forming the insulating layer have an average particle diameter of less than 100 nm (Invention 2).

  Further, the present invention is the soft magnetic particle powder according to any one of the present invention 1 or 2, wherein the specific resistance after heating at 600 ° C. for 1 hour is 80% or more with respect to the specific resistance before heating. (Invention 3).

  Further, the present invention forms an insulating layer on the particle surface of the soft magnetic metal particle powder by premixing the soft magnetic metal particle powder and the oxide fine particle and then applying mechanical energy consisting of compression and shear force. (Invention 4).

  In addition, the present invention is a powder magnetic core obtained by compression-molding the soft magnetic material particle powder according to any one of the first to third aspects (Invention 5).

  Since the soft magnetic particle powder according to the present invention has an insulating layer excellent in heat resistance, it is suitable as a soft magnetic material for a dust core.

  The method for producing a soft magnetic particle powder according to the present invention is a method that is industrially advantageous without using a solution such as an organic solvent, and has a uniform insulation with excellent adhesion to the surface of the soft magnetic metal particle. Since a layer can be formed, it is suitable as a method for producing a soft magnetic material for a dust core.

  The powder magnetic core according to the present invention is suitable as a high-performance powder magnetic core because the use of the soft magnetic particle powder prevents specific resistance from being lowered even when fired at a high temperature.

  The configuration of the present invention will be described in more detail as follows.

  First, the soft magnetic particle powder according to the present invention will be described.

  The soft magnetic particle powder according to the present invention is a soft magnetic metal particle powder having an insulating layer on the particle surface, and the insulating layer is one selected from aluminum, silicon, magnesium, titanium, zirconium, yttrium, and calcium, or It consists of two or more kinds of oxide fine particles.

  The oxide fine particles forming the insulating layer of the soft magnetic particle powder according to the present invention are composed of one or two selected from alumina, silica, magnesia, titania, zirconia, yttria, and calcia. In view of heat resistance, alumina, silica and yttria are particularly preferable.

  The average particle diameter of the oxide fine particles forming the insulating layer of the soft magnetic particle powder according to the present invention is less than 100 nm, preferably 1 to 80 nm, more preferably 3 to 50 nm. When the average particle diameter of the oxide fine particles is 100 nm or more, it becomes difficult to uniformly treat the surface of the soft magnetic metal particles in the insulating layer made of the oxide fine particles.

  In the soft magnetic particle powder according to the present invention, the ratio of the average particle diameter of the soft magnetic metal particles to the oxide fine particles forming the insulating layer is 1000 or more, preferably 2000 or more, more preferably 3000 or more. When the ratio of the average particle diameter of the soft magnetic metal particle powder to the oxide fine particles forming the insulating layer is less than 1000, it is difficult to uniformly treat the surface of the insulating layer made of oxide fine particles on the soft magnetic metal particle surface. .

  The coating amount of the insulating layer made of oxide fine particles of the soft magnetic particle powder according to the present invention depends on the specific surface area of the soft magnetic metal particle powder as the particles to be treated, but is 0.005 in terms of element of each oxide fine particle. -5.0 wt% is preferred. By forming the insulating layer in the range of 0.005 to 5.0% by weight, a soft magnetic particle powder having excellent heat resistance can be obtained. When the content exceeds 5.0% by weight, the fine oxide particles that do not participate in magnetism increase, and the volume ratio of the soft magnetic metal powder in the dust core decreases, so that the magnetic properties deteriorate. Considering the magnetic properties of the obtained soft magnetic particle powder material, 0.075 to 4.0% by weight is more preferable, and still more preferably 0.01 to 3.0% by weight.

  The average particle size of the soft magnetic particle powder according to the present invention may be selected according to the use and characteristics, but is preferably in the range of 1.0 to 500.0 μm. When the average particle diameter exceeds 500.0 μm, the particle diameter is too large, and when used for a dust core, the packing density is lowered, which is not preferable. An average particle size of less than 1.0 μm is not preferable because the particle size is too small and fluidity and compression moldability are reduced. More preferably, it is 2.0-400.0 micrometers, More preferably, it is 3.0-300.0 micrometers.

  The heat resistance of the soft magnetic particle powder according to the present invention is preferably such that the specific resistance after heating at 600 ° C. for 1 hour is 80% or more with respect to the specific resistance before heating. When the heat resistance is less than 80%, the heat resistance of the insulating layer cannot be said to be sufficient, and annealing at a high temperature to release the strain applied to the soft magnetic metal particle powder after compression molding cannot be performed. . For this reason, the powder magnetic core produced using the soft magnetic metal particle powder thus obtained cannot reduce the hysteresis loss, and thus it is difficult to reduce the iron loss. More preferably, it is 90% or more, and still more preferably 95% or more.

  Next, a method for producing the soft magnetic particle powder according to the present invention will be described.

  The soft magnetic particle powder according to the present invention is obtained by premixing the soft magnetic metal particle powder and the oxide fine particle, and then applying mechanical energy consisting of compression and shear force to act on the surface of the soft magnetic metal particle powder. Can be obtained.

  As a device for premixing soft magnetic metal particle powder and oxide fine particles, a container rotating type is preferable, and a mill or a mixer of a type in which an outer container rotates or rolls (for example, a gravity mixer such as a concrete mixer). It is preferable to use a blender. If a mill or mixer with a fixed external container is used for premixing, there is a difference in specific gravity between the soft magnetic metal particle powder and the oxide fine particle. The oxide fine particles having a low particle size are separated upward and cannot be mixed uniformly.

  In practicing the present invention, it is important to premix the soft magnetic metal particle powder and the oxide fine particle, and without applying premix, the soft magnetic metal particle powder and the oxide fine particle are directly compressed and sheared. When the treatment is performed in an apparatus capable of processing, the treatment is biased due to the difference in specific gravity between the soft magnetic metal particle powder and the oxide fine particle, so that a uniform insulating layer is formed on the particle surface of the soft magnetic metal particle powder. It is difficult to form.

  It is preferable to confirm that the soft magnetic metal particle powder and the oxide fine particle are uniformly mixed by premixing. As a method for this, sampling is performed from several places of the obtained mixed particle powder, and fluorescence is obtained. This is done by confirming the content with X-rays.

  The mixed particle powder of soft magnetic metal particle powder and oxide fine particle obtained by premixing is then subjected to mechanical energy consisting of compression and shear force to form an insulating layer on the surface of the soft magnetic metal particle powder. To do. As an apparatus capable of applying a compressive / shearing force to the powder layer, for example, a wheel-type kneader, a high-speed shear mill, a ball-type kneader, a blade-type kneader, a roll-type kneader, or a planetary mill can be used. . In carrying out the present invention, a wheel-type kneader, a high-speed shear mill, and a ball-type kneader can be used more effectively.

  Specific examples of the wheel-type kneader include edge runners (synonymous with “mix muller”, “Simpson mill”, “sand mill”), multi-mal, stotz mill, wet pan mill, conner mill, ring muller, and the like. , Preferably an edge runner, multi-mal, Stots mill, wet pan mill, and ring muller, and more preferably an edge runner. Examples of the high-speed shear mill include a hybridizer (manufactured by Nara Machinery Co., Ltd.) and nobilta (manufactured by Hosokawa Micron). Examples of the ball kneader include an attritor and a vibration mill. Examples of the blade-type kneader include a Henschel mixer, a planetary mixer, and a nauter mixer. Examples of the roll-type kneader include an extruder.

  As the soft magnetic metal particle powder in the present invention, iron powder by various production methods such as atomized iron powder, reduced iron powder, carbonyl iron powder, silicon steel powder, sendust powder, permalloy powder, permender powder and the like can be used. Considering the permeability and magnetic flux density of the obtained dust core, iron powder is preferred. The average particle diameter of the soft magnetic metal particle powder is preferably 1.0 to 500.0 μm, more preferably 2.0 to 400.0 μm, and still more preferably 3.0 to 300.0 μm.

  Next, the dust core according to the present invention will be described.

  The powder magnetic core according to the present invention is obtained by mixing the soft magnetic particle powder according to the present invention with an additive such as a lubricant such as zinc stearate and a binder resin, if necessary, and compressing the mixed particle powder. It can be obtained by heat treatment.

  As the binder resin, an epoxy resin, an imide resin, a phenol resin, a silicone resin, or the like can be used alone or in combination.

  The compression molding can be performed by a compression molding method using a mold that is usually performed. In addition, what is necessary is just to select a shaping | molding pressure suitably according to a use.

  The annealing temperature for strain relief after compression molding is preferably a high temperature at which the magnetic particles themselves do not cause particle growth due to thermal diffusion. Preferably it is 500-1200 degreeC, More preferably, it is 600-1000 degreeC. The annealing atmosphere is desirably performed in an inert gas atmosphere such as nitrogen or Ar gas, in a reducing atmosphere such as hydrogen, or in a non-oxidizing atmosphere such as vacuum.

  In the dust core according to the present invention, the specific resistance after annealing at high temperatures (600 ° C. and 700 ° C.) is higher than the specific resistance of the dust core obtained by using the untreated soft magnetic metal particle powder. have.

<Action>
The most important point in the present invention is a soft magnetic metal particle powder having an insulating layer on the particle surface, and the insulating layer has an average particle diameter of less than 100 nm, such as aluminum, silicon, magnesium, titanium, zirconium, yttrium, The fact is that the soft magnetic particle powder composed of one or more oxide fine particles selected from calcium has an insulating layer excellent in heat resistance.

  As the reason why the heat resistance of the soft magnetic particle powder according to the present invention is excellent, the present inventor limited the particle size of the oxide powder forming the insulating layer to a fine particle powder of less than 100 nm and the premix. This is considered to be because a uniform insulating coating could be formed on the surface of the soft magnetic metal particles.

  Hereinafter, the present invention will be described in detail with reference to examples.

  The average particle diameter of each particle powder was measured by measuring the particle diameters of 50 to 350 particles shown in the electron micrographs, and indicated by the average value.

  The average particle size of each particle measured from the above-mentioned electron micrograph was used as the ratio of the average particle size of the soft magnetic metal particle powder and the oxide fine particle.

  To check the uniformity of the mixed particle powder after premixing the soft magnetic metal particle powder and the oxide fine particle, randomly sample 5 points and select "X-ray fluorescence analyzer 3063M type" (manufactured by Rigaku Corporation) The content of the oxide fine particles in the mixed particle powder was judged to be almost the same as the blending ratio of the soft magnetic metal particle powder and the oxide fine particles at the time of preparation.

  The coating amount of the insulating layer made of oxide fine particles formed on the surface of the soft magnetic particle powder is “X-ray fluorescence analyzer 3063M type” (manufactured by Rigaku Denki Kogyo Co., Ltd.). Measurement was performed according to the "General Rules for Optical X-ray Analysis"

  The uniformity of the insulating layer made of oxide fine particles formed on the surface of the soft magnetic metal particle is confirmed visually using “Scanning Electron Microscope S-4800” (manufactured by Hitachi, Ltd.) and “EDX”. Genesis ”(manufactured by EDAX) was used to perform mapping of the oxide fine particles used for forming the insulating layer with metal atoms and confirm the existence state on the surface of the soft magnetic metal particles.

  The heat resistance of the soft magnetic particle powder was determined by measuring the specific resistance (ρ1) of the unheated soft magnetic particle powder and the specific resistance (ρ2) of the soft magnetic particle powder after heating at 600 ° C. for 1 hour, respectively, Each value was inserted into and the obtained value was shown as heat resistance (rate of change in specific resistance before and after heating) (%).

<Equation 1>
Heat resistance (%) = (ρ2 / ρ1) × 100

The specific resistance was measured by a four-terminal method while setting a sample powder on a sample stage and applying a load from 0 to 40 MPa, and the specific resistance at 40 MPa was used.

  The specific resistance of the powder magnetic core is as follows. First, 6.0 g of soft magnetic particle powder is measured and subjected to pressure molding at a molding pressure of 686 MPa with a 10-ton press using a ring molding die having an outer diameter of 20 mm and an inner diameter of 10 mm. A plurality of ring molded bodies were produced, and the press surface of the ring molded body was measured by applying a voltage of 10 V with a 1 mm pitch 4-terminal electrical resistance measuring device (Loresta GP / MCP-T600, manufactured by Mitsubishi Kasei).

  The specific resistance after annealing of the powder magnetic core is the same as the measurement of the specific resistance described above, after the ring molded body prepared above was heated at 600 ° C. and 700 ° C. for 1 hour in a nitrogen atmosphere. Asked.

<Example 1-1: Production of soft magnetic particle powder>
Soft magnetic metal particle powder A (type: iron powder, particle shape: granular, average particle diameter: 115.0 μm, specific resistance: 116.2 mΩ · cm) 5 kg and oxide fine particles A (type: alumina, average particle diameter: 13 gm) was premixed with a gravitational mixer to obtain mixed particle powder. The obtained mixed particle powder was randomly sampled at five points, and the content of the oxide fine particles A in the mixed particle powder was measured by fluorescent X-rays at all five points. It was confirmed that the blending ratio with the fine particles A was almost the same.

  Next, 1010 g of the obtained mixed particle powder was put into a high-speed shearing mill, and subjected to high-speed shearing treatment at a rotational speed of 2000 rpm for 10 minutes to obtain soft magnetic particle powder.

  The obtained soft magnetic particle powder was a granular particle having an average particle diameter of 115.3 μm, a specific resistance of 2376 mΩ · cm, and a heat resistance of 606%. The oxide fine particles constituting the insulating layer was 0.53% by weight in terms of Al, and the particle size ratio of the soft magnetic metal particles to the oxide fine particles was 8846.

As a result of observation by an electron microscope, the oxide fine particles A used for forming the insulating layer are formed almost uniformly on the particle surface of the soft magnetic metal particle powder A, and aluminum is soft magnetic metal particles by EDX mapping. It was confirmed that the powder A was present evenly on the particle surface.

<Example 2-1: Production of dust core>
6.0 g of the soft magnetic particle powder was weighed and compression molded into a ring shape (φ20 × φ10 mm) at a molding pressure of 686 MPa using a die coated with zinc stearate to obtain a dust core (ring compact). .

  The specific resistance (600 ° C.) after annealing at 600 ° C. for 1 hour of the obtained powder magnetic core was 160 mΩ · cm, and the specific resistance (700 ° C.) after annealing at 700 ° C. for 1 hour was 68 mΩ · cm.

  Soft magnetic particle powders and dust cores were prepared according to Examples 1-1 and 2-1. Various characteristics of each production condition and the obtained soft magnetic particle powder and dust core are shown.

Soft magnetic metal particles A to E:
A soft magnetic metal particle powder having the characteristics shown in Table 1 was prepared as a particle to be treated.

Oxide fine particles A to E:
Oxide fine particles having the characteristics shown in Table 2 were prepared as oxide fine particles constituting the insulating layer.

Examples 1-2 to 1-5, Comparative Examples 1-1 to 1-3:
A soft magnetic particle powder was obtained in the same manner as in Example 1-1 except that the type of soft magnetic metal particle powder, the type of oxide fine particles, and the amount added were variously changed.

  The production conditions at this time are shown in Table 3, and various properties of the obtained soft magnetic particle powder are shown in Table 4.

  In Comparative Example 1-1, 1 kg of soft magnetic metal particle powder A and 10 g of oxide fine particles A were put in a high-speed shearing mill without premixing, and subjected to high-speed shearing treatment for 10 minutes at a rotational speed of 2000 rpm. The soft magnetic particle powder of Example 1-1 was obtained.

  Further, in Comparative Example 1-2, 5 kg of soft magnetic metal particle powder A and 50 g of oxide fine particles A were used as an edge runner “MPUV-2 type” (product name, manufactured by Matsumoto Casting Co., Ltd.) (an external container was fixed). Was mixed for 20 minutes at a line load of 588 N / cm to obtain mixed particle powder. The obtained mixed particle powder was randomly sampled at five points, and the content of oxide fine particles A in the mixed particle powder was examined using fluorescent X-rays. And the amount of oxide fine particles A were not consistent, and the variation was large. Next, 1010 g of the obtained mixed particle powder was put in a high-speed shearing mill, and subjected to high-speed shearing treatment at a rotation speed of 2000 rpm for 10 minutes to obtain a soft magnetic particle powder of Comparative Example 1-2.

Examples 2-2 to 2-5, comparative examples 2-1 to 2-8:
A dust core was obtained in the same manner as in Example 2-1, except that various types of soft magnetic particle powder were used.

  Table 5 shows various characteristics of the obtained dust core.

  Since the soft magnetic material according to the present invention has an insulating layer having excellent heat resistance, it is suitable as a soft magnetic material for a dust core.

The powder magnetic core according to the present invention is suitable as a high-performance powder magnetic core because the use of the soft magnetic particle powder prevents specific resistance from being lowered even when fired at a high temperature.

Claims (5)

Soft magnetic metal particle powder having an insulating layer on the particle surface, wherein the insulating layer is made of one or more oxide fine particles selected from aluminum, silicon, magnesium, titanium, zirconium, yttrium, and calcium. Soft magnetic particle powder characterized by The soft magnetic particle powder according to claim 1, wherein the oxide fine particles forming the insulating layer have an average particle diameter of less than 100 nm. 3. The soft magnetic particle powder according to claim 1, wherein a specific resistance after heating at 600 ° C. for 1 hour is 80% or more with respect to a specific resistance before heating. Soft magnetism characterized in that after premixing soft magnetic metal particle powder and oxide fine particles, mechanical energy consisting of compression and shear force is applied to form an insulating layer on the surface of soft magnetic metal particle powder Production method of particle powder. A dust core obtained by compression-molding the soft magnetic material particle powder according to any one of claims 1 to 3.