CN112420309B - Dust core - Google Patents
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- CN112420309B CN112420309B CN202010829482.7A CN202010829482A CN112420309B CN 112420309 B CN112420309 B CN 112420309B CN 202010829482 A CN202010829482 A CN 202010829482A CN 112420309 B CN112420309 B CN 112420309B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F3/00—Cores, Yokes, or armatures
- H01F3/08—Cores, Yokes, or armatures made from powder
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F3/00—Cores, Yokes, or armatures
- H01F3/10—Composite arrangements of magnetic circuits
- H01F3/14—Constrictions; Gaps, e.g. air-gaps
Abstract
The present invention provides a powder magnetic core (100) which comprises: the magnetic core comprises a plurality of soft magnetic iron-based particles (10), coating layers (20) respectively arranged on the surfaces of the soft magnetic iron-based particles (10), an interlayer (40) arranged between the coating layers (20), and nano powder (30) arranged between the soft magnetic iron-based particles (10). The coating layer (20) is a layer containing a compound of Fe, Si, O, B and N, and the nano-powder (30) is a powder containing at least one element selected from the group consisting of Fe, Si, Zr, Co, Al, Mg, Mn and Ni, and a compound of O and N.
Description
Technical Field
The present invention relates to a dust core.
Background
As electronic components such as choke coils, reactors, motors, and inductors are downsized and lightened in electric devices, magnetic materials used for the electronic components are required to have low magnetic loss (core loss) and high magnetic permeability. Various kinds of powder magnetic cores have been developed with the aim of improving magnetic permeability and reducing magnetic loss.
For example, patent document 1 discloses a technique relating to a composite magnetic material comprising a metal magnetic material having a Vickers hardness (Hv) in a range of 230 Hv 1000 and a compressive strength of 10000kg/cm2(980.07MPa) or less.
Patent document 2 discloses a technique relating to a silica-based insulation-coated dust core having high resistance and high magnetic flux density, a method for producing the same, and an electromagnetic circuit component.
Documents of the prior art
Patent document
Patent documents: WO2010/082486 publication
Patent document 2: japanese laid-open patent publication No. 2017-188678
Disclosure of Invention
Problems to be solved by the invention
However, in the technique of patent document 1, when the insulating material is reduced in order to obtain a high molding density, the metal particles cannot be prevented from contacting each other, and it is difficult to reduce the magnetic loss. In the technique of patent document 2, it is difficult to uniformly form a thin grain boundary layer of 1 μm or less between metal particles, and it is difficult to obtain both high magnetic permeability and low core loss.
The present invention has been made in view of the above problems, and an object thereof is to provide a powder magnetic core having low magnetic loss and high magnetic permeability.
Means for solving the problems
The present invention provides a dust core, comprising: a plurality of soft magnetic iron-based particles; coating layers provided on the surfaces of the soft magnetic iron-based particles, respectively; an interlayer disposed between the cladding layers; and a nano powder disposed between the soft magnetic iron-based particles. The coating layer is a layer containing a compound of Fe, Si, O, B and N, and the nano-powder is a powder containing at least one element selected from the group consisting of Fe, Si, Zr, Co, Al, Mg, Mn and Ni, and a compound of O and N.
Here, the nano powder may be a powder containing compounds of Fe, Si, O and N.
The average particle diameter of the nano powder can be 10 to 200 nm.
In addition, the average thickness of the coating layer can be 1 to 100 nm.
The soft magnetic iron-based particles may have an average particle diameter of 1 to 100 μm.
In addition, the soft magnetic iron-based particles may be Fe-Si alloy particles, and the apparent density of the dust core may be 6.6g/cm3The above.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, a powder magnetic core having low magnetic loss and high magnetic permeability is provided.
Drawings
Fig. 1 is an enlarged sectional view of a dust core according to an embodiment of the present invention.
Description of the symbols
10 … soft magnetic iron-based particles, 20 … coating layer, 30 … nanopowder, 40 … sandwich layer, 100 … dust core.
Detailed Description
(dust core)
The powder magnetic core according to the embodiment of the present invention will be explained. Fig. 1 is an enlarged sectional view of a powder magnetic core according to an embodiment of the present invention.
A powder magnetic core (core) 100 according to an embodiment of the present invention includes: the magnetic core includes a plurality of soft magnetic iron-based particles 10, coating layers 20 provided on the surfaces of the soft magnetic iron-based particles 10, respectively, an intervening layer 40 provided between the coating layers 20, and a nano powder 30 disposed between the soft magnetic iron-based particles 10.
(Soft magnetic iron-based particles)
Soft magnetic iron-based particles are particles that have soft magnetism, and the element that exhibits the largest atomic fraction among the elements in the particles is Fe. The atomic fraction of Fe may be 50 at% or more.
Examples of soft magnetic iron-based materials are pure iron, carbonyl iron (carbonyl iron), Fe-Si alloys, Fe-Al alloys, Fe-N compounds, Fe-Ni alloys, Fe-C compounds, Fe-B compounds, Fe-Co alloys, Fe-Al-Si alloys, Fe-Al-Cr alloys, Fe-Al-Mn alloys, Fe-Al-Ni alloys, Fe-Si-Cr alloys, Fe-Si-Mn alloys, Fe-Si-Ni alloys. The soft magnetic iron-based material may be a crystalline material, an amorphous material, or a nanocrystalline material.
The average particle diameter of the soft magnetic iron-based particles 10 is not particularly limited, and may be 1 to 100 μm. The lower limit of the average particle diameter may be 3 μm or 5 μm. The upper limit may be 50 μm or 30 μm.
Further, the average particle diameter of the soft magnetic iron-based particles 10 can be determined as follows: in an electron micrograph (for example, SEM) of the cross section of the powder magnetic core, 30 cross-sectional areas of the soft magnetic iron-based particles were obtained, and the equivalent circle diameters of the equal areas were calculated and arithmetically averaged.
In addition, the soft magnetic iron-based particles 10 may have one or more oxidized regions 10a inside thereof along the interface of the clad layer 20. For example, the oxidized region 10a may have a spherical shape and may be present in a region having a depth of 500nm from the interface. The diameter of the oxidized region 10a can be 1 to 20 nm. The diameter can be measured in the same manner as the diameter of the nano-powder described later. By including the oxidized region 10a in the soft magnetic iron-based particles 10, the resistivity becomes high, and the eddy current loss in the particles is reduced. When the diameter of the oxidized region 10a is less than 1nm, the effect of reducing the eddy current loss becomes low. When the diameter of the oxidized region exceeds 20nm, the magnetic permeability tends to decrease.
(coating layer)
The clad layer 20 covers the surface of the soft magnetic iron-based particles 10. The coating layer 20 preferably covers the entire surface of the soft magnetic iron-based particles 10.
The average thickness of the clad layer 20 can be 1nm or more, preferably 5nm or more, and more preferably 10nm or more. The average thickness of the clad layer 20 can be 100nm or less, preferably 70nm or less. When the coating layer 20 is too thick, the density after press molding tends to decrease, while when it is too thin, the soft magnetic iron-based particles 10 may come into contact with each other during press molding.
The average thickness of the clad layer 20 can be determined as follows. From the cross-sectional photographs, 10 soft magnetic iron-based particles were randomly selected. The thickness of each coating layer was measured at 10 points arranged at equal intervals along the interface between each soft magnetic iron-based particle and the coating layer in the sectional photograph, and the arithmetic mean a was obtained for each coating layer of each soft magnetic iron-based particle. The arithmetic mean a of the clad layers of 10 soft magnetic iron-based particles was further subjected to arithmetic mean.
The coating layer is an electrically insulating layer and contains at least compounds of Fe, Si, O, B and N. This increases the adhesion to the soft magnetic iron-based particles 10 and also increases the insulation properties.
(sandwiching layer)
The intermediate layer 40 is a layer filled between the clad layers 20, and bonds the soft magnetic iron-based particles 10 having the clad layers 20 to each other. Examples of the material of the interlayer 40 are epoxy resin, phenol resin, polyamide resin, and silicone resin. The interlayer may be a thermoplastic resin, preferably a thermosetting resin. At least a part or the whole of the interlayer may be a thermal decomposition product of the resin.
(Nano-powder)
The nano-powder 30 is disposed between the soft magnetic iron-based particles 10. That is, the nano-powder 30 may be disposed in the coating layer 20, may be disposed in the interlayer 40, or may be disposed at the interface between the coating layer 20 and the interlayer 40.
The average particle diameter of the nano-powder 30 is 200nm or less. The upper limit of the average particle diameter may be 200nm, or 150nm, preferably 100nm, and more preferably 80 nm. The lower limit of the average particle diameter is not particularly limited, and may be 1nm, preferably 5nm, and more preferably 10 nm. The particle diameter of the nano powder 30 is an equivalent diameter of an equivalent circle of an equal area in an electron micrograph (for example, TEM) of a cross section of the composite particle, and the average particle diameter can be an arithmetic average of particle diameters of about 30 nano particles.
The nano-powder 30 is a powder containing at least one element selected from Fe, Si, Zr, Co, Al, Mg, Mn, and Ni, and a compound of O (oxygen) and N (nitrogen). Such an oxynitride of the metal element and/or the semimetal element is preferable because electrical insulation and toughness are ensured. In particular, by containing N (nitrogen), toughness is improved as compared with an oxide, and contact between soft magnetic particles is easily suppressed even after pressurization.
The nanopowder can be a compound or a composite particle population. As an example, the compound can be SiON powder (e.g., Si)2N2O powder), AlON powder, SiAlON powder and ZrON powder.
The nano-powder 30 is preferably a powder containing compounds of Fe, Si, O and N. The nano-powder 30 is a compound containing Fe and Si, and can further exhibit magnetic properties, and thus magnetic properties such as magnetic permeability are further improved.
As an index relating to the dispersibility of the nanoparticles, the area ratio of the nanopowder in the TEM cross section of the dust core can be cited. The area ratio is preferably 10% to 50%, more preferably 10% to 40%, in the TEM cross-sectional photograph, of the ratio of the total area of the nanoparticles to the area between the soft magnetic iron-based particles (the area of the coating layer and the interposed layer) (the total area of the nanoparticles/the area between the soft magnetic iron-based particles). When the area ratio is 50% or less, the density of the dust core becomes high. In the area ofWhen the ratio is 10% or more, the insulation property of the powder magnetic core is good. The area between the soft magnetic iron-based particles in the TEM cross-section is preferably 0.01. mu.m2～0.1μm2The mode of (2) is set.
In the case where the soft magnetic iron-based particles are Fe — Si alloy particles, the apparent density of the dust core 100 can be 6.6g/cm3Above, it can be 6.7g/cm3The above. In the case where the soft magnetic iron-based particles are Fe-Ni-Si alloy particles, the apparent density of the dust core 100 is preferably 7.3g/cm3The above. When the soft magnetic iron-based material is a particle containing 99.5 mass% or more of Fe, such as carbonyl iron, the apparent density of the dust core 100 is preferably 6.9g/cm3The above. The filling ratio of the soft magnetic iron-based particles 10 contained in the dust core 100 is preferably 88% or more. The filling ratio of the dust core will be explained later.
The shape of the dust core is not particularly limited. For example, a toroidal (annular) core, a cut core (U core) such as a U-shape, a laminated core for a motor or an inductor, and the like are possible.
(Effect)
According to the dust core of the present embodiment, the electrical insulation between the soft magnetic iron-based particles 10 is increased by including Fe, Si, O, B, and N in the coating layer 20. Further, since the nano-powder 30 such as oxynitride of a specific metal is interposed between the soft magnetic iron-based particles 10, it has toughness as compared with the case where oxide particles are interposed, and it is easy to secure the gaps between the soft magnetic particles even after high-pressure pressing, and it is possible to suppress contact between the soft magnetic iron-based particles, improve electrical insulation, and reduce the gaps between the soft magnetic iron-based particles.
This can improve magnetic permeability and reduce magnetic loss.
(method of manufacturing dust core)
A first example of the method for producing a powder magnetic core (external addition of a nano-powder) will be described.
First, a mixed powder of soft magnetic iron-based particles, BN powder, and nano powder is prepared. Spherical soft magnetic iron-based particles are preferably used. By forming the spherical shape, the points of approach of the soft magnetic iron-based particles 10 to each other are reduced, and electrical insulation is easily ensured.
The average particle diameter of the BN powder is preferably sufficiently smaller than that of the soft magnetic iron-based particles, and can be, for example, 20nm to 4 μm. BN is preferably hexagonal (h-BN). The average particle diameters of the soft magnetic iron-based particles and the BN powder were D50 of the volume-based particle size distribution measured by a wet laser diffraction scattering method.
Then, the mixed powder is heat-treated in nitrogen at about 400 to 700 ℃. Thereby, the coating layer 20 including the nano powder 30 is formed on the surface of each soft magnetic iron-based particle, and the composite particle is obtained.
Next, the obtained composite particle group is mixed with a binder raw material to obtain a mixture. The solvent in the binder raw material is dried as necessary.
Next, a lubricant may be mixed into the mixture as needed. An example of a lubricant is zinc stearate.
Next, the above mixture is filled into a metal mold having a void corresponding to the shape of the powder magnetic core, and pressure molding is performed to obtain a powder magnetic core having a desired shape. The inner surface of the metal mold is preferably coated with a lubricant in advance.
The pressure during the press molding is not particularly limited, and may be 981 to 1570 MPa.
After or during the press molding, the binder material may be cured and/or the soft magnetic iron-based particles may be annealed by heating as necessary.
Next, a second example (nano-powder internal synthesis) of the method for producing a powder magnetic core will be described.
In the present embodiment, a mixture of soft magnetic iron-based particles and BN powder is heat-treated in nitrogen at 800 to 1100 ℃, preferably at about 900 to 1000 ℃, to obtain composite particles having the soft magnetic iron-based particles, a coating layer 20 provided on the surface of the soft magnetic iron-based particles, and a nano powder 30 disposed in the coating layer 20. The nano-powder 30 can be formed from soft magnetic iron-based particles, and therefore, does not need to be added from the outside.
The subsequent steps are the same as in the first method.
Examples
(example 1)
A gas atomized Fe-Si (4.5 mass%) alloy powder having an average particle size of 5 μm, a BN powder having an average particle size of 4 μm and a SiON powder having an average particle size of 180nm were prepared. Mixing Fe-Si alloy powder, BN powder and SiON powder in a weight ratio of 50: 10: 1 to obtain a powder mixture.
Next, the powder mixture was charged into a crucible, and heat treatment was performed at 500 ℃ for 30 minutes in a nitrogen atmosphere to obtain composite particles of a nanopowder having a coating layer containing a compound of B, O, N, Fe, and Si on the surface of the Fe — Si alloy powder and SiON disposed in the coating layer.
Unreacted BN powder and free SiON powder remaining in the composite particles were removed by alcohol.
To the obtained composite particle group, 1 wt% of a silicone resin was added, mixed and dried. To the dry matter was added 0.1 wt% of a lubricating material (zinc stearate) and further mixed. 5g of the final mixture was filled into a metal mold previously coated with zinc stearate and pressed with a forming pressure of 1570 MPa. Then, annealing was performed at 900 ℃ for 30 minutes in a nitrogen atmosphere to obtain a toroidal core as a dust core. The filling ratio, apparent density, magnetic loss and specific permeability of the toroidal core were measured as follows.
The filling ratio (a) is calculated based on the ratio (a ═ C/B x 100) of the apparent density (C) of the toroidal core to the true density (B) calculated from the composition of the metal and semimetal elements contained in the toroidal core.
The true density (B) is calculated from the sum of the products of the mass ratio of the metal and semimetal elements contained in the toroidal core and the density of each element. For example, the soft magnetic iron-based particles of examples 1, 6, and 7 were calculated as follows.
In the case of the Fe — Si (4.5 mass%) alloy particles of examples 1 to 5 and comparative examples 1 and 2, (7.87 × (100.0 to 4.5) +2.33 × 4.5)/100 ═ 7.62g/cm3。
The Fe (52.0 mass%) -Ni (47.0 mass%) -Si (1.0 mass%) alloy particles of example 6 and comparative examples 3 and 4In the case of (7.87 × (100.0-47.0-1.0) +8.90 × 47.0+2.33 × 1.0)/100 ═ 8.30g/cm3。
In the case of the Fe (99.5 mass%) particles of example 7 and comparative examples 5 and 6, the amount was 7.87 × 0.995 — 7.83g/cm3。
The apparent density was calculated by measuring the size and weight of the toroidal core.
The magnetic permeability was measured as follows. Inductance of the dust core at a frequency of 20kHz was measured by an LCR meter (4284A, manufactured by Agilent Technologies) and a DC bias power supply (42841A, manufactured by Agilent Technologies), and magnetic permeability of the dust core at room temperature was calculated from the inductance. The DC superimposed magnetic field was measured at 8000A/m.
The magnetic loss was measured as follows. A sine wave AC magnetic field of 50mT at maximum was applied using a BH analyzer (SY8258) manufactured by Kawasaki communications, Inc., and the loss at 500kHz at room temperature was measured.
The magnetic loss is preferably 1200kW/m3Hereinafter, the specific magnetic permeability is preferably 45 or more.
The area ratio of the nanopowder (the total area of the nanoparticles/the area between the soft magnetic iron-based particles) in the cross section of the dust core was measured. A dust core was cut with an FIB (Nova200i) manufactured by FEI of Japan to prepare a chip sample, which was observed with a STEM-EDS (JEM2100FCS) manufactured by JEOL. The STEM images observed by STEM were measured for the area between the soft magnetic iron-based particles and the area of the nanopowder using image analysis software (Pixs2000Pro (ver2.2.2)) manufactured by Innotech. 5 TEM photographs of different sites taken on the cross section of one dust core were prepared, and the area ratios of the two were measured to obtain the arithmetic mean.
Comparative example 1
A toroidal core of comparative example 1 was obtained in the same manner as in example 1 except that the weight ratio of the Fe-Si alloy powder to the BN powder was set to 1: 1 and that the SiON powder was not used.
Comparative example 2
An alcohol solution containing 2 wt% of SiON powder and 1 wt% of phosphoric acid based on the weight of Fe — Si powder was supplied to a gas atomized Fe — Si (4.5 mass%) alloy powder having an average particle size of 5 μm, and the alcohol was dried to form an iron phosphate coating layer containing a nano powder on the surface of the Fe — Si alloy powder. Thereafter, a toroidal core of comparative example 2 was obtained in the same manner as in example 1.
(example 2)
A gas atomized Fe-Si (4.5 mass%) alloy powder having an average particle size of 5 μm and a BN powder having an average particle size of 4 μm were prepared. Mixing Fe-Si alloy powder and BN powder according to the weight ratio of 5: 1 to obtain a powder mixture.
Next, the powder mixture was charged into a crucible, and heat treatment was performed at 900 ℃ for 30 minutes in a nitrogen atmosphere to form a coating layer containing compounds of B, O, N, Fe, and Si and a nano-powder containing compounds of O, N, Si, and Fe disposed in the coating layer on the surface of the Fe — Si alloy powder, thereby obtaining composite particles. Thereafter, a toroidal core of example 2 was obtained in the same manner as in example 1 except that the SiON powder was not added.
(example 3)
A toroidal core of example 3 was obtained in the same manner as in example 2, except that Fe — Si (4.5 mass%) powder was atomized using a gas having an average particle size of 10 μm.
(example 4)
A toroidal core of example 4 was obtained in the same manner as in example 2, except that the weight ratio of the Fe-Si alloy powder to the BN powder was set to 1: 1.
(example 5)
A toroidal core of example 5 was obtained in the same manner as in example 2, except that the weight ratio of the Fe-Si alloy powder to the BN powder was set to 100: 1.
(example 6)
A gas atomized Fe-Ni (47.0 mass%) -Si (1.0 mass%) alloy powder having an average particle size of 5 μm and a BN powder having an average particle size of 4 μm were prepared. Mixing Fe-Ni-Si alloy powder and BN powder in a weight ratio of 5: 1 to obtain a powder mixture.
Next, the powder mixture was charged into a crucible, and heat treatment was performed at 1100 ℃ for 60 minutes in a nitrogen atmosphere to form a coating layer containing compounds of B, O, N, Fe, and Si and a nano-powder containing compounds of O, N, Si, and Fe disposed in the coating layer on the surface of the Fe — Ni — Si alloy powder, thereby obtaining composite particles.
The unreacted BN powder remaining in the composite particles was removed by alcohol.
To the obtained composite particle group, 1 wt% of a silicone resin was added, mixed and dried. To the dry matter was added 0.1 wt% of a lubricating material (zinc stearate) and further mixed. 5g of the final mixture was filled in a metal mold previously coated with zinc stearate and pressed at a molding pressure of 1570 MPa. Then, annealing was performed at 600 ℃ for 30 minutes in a nitrogen atmosphere to obtain a toroidal core as a dust core.
Comparative example 3
Composite particles were produced in the same manner as in example 1, except that the soft magnetic iron-based particles were the Fe-Ni-Si alloy powder of example 6, the weight ratio of the Fe-Ni-Si alloy powder to the BN powder was 1: 1, and the SiON powder was not used. Then, a toroidal core of comparative example 3 was obtained in the same manner as in example 1, except that the annealing conditions were 600 ℃ for 30 minutes.
Comparative example 4
An alcohol solution containing 2 wt% of SiON powder and 1 wt% of phosphoric acid based on the weight of the Fe-Ni-Si powder was supplied to the Fe-Ni-Si alloy powder of example 6, and then the alcohol was dried to form an iron phosphate coating layer containing a nano powder on the surface of the Fe-Ni-Si powder. Thereafter, a toroidal core of comparative example 4 was obtained in the same manner as in example 6.
(example 7)
Carbonyl iron powder (Fe99.5 mass%) having a particle size of 4 μm, BN powder having a particle size of 4 μm, and TEOS (SiO (C)2H5)4). Mixing carbonyl powder, BN powder and TEOS at a weight ratio of 5: 1: 0.01 to obtain a powder mixture.
Next, the powder mixture was charged into a crucible, and heat treatment was performed at 750 ℃ for 30 minutes in a nitrogen atmosphere, thereby forming a coating layer containing compounds of B, O, N, Fe, and Si and a nano-powder containing compounds of O, N, Si, and Fe disposed in the coating layer on the surface of the carbonyl iron powder, and obtaining composite particles.
The unreacted BN powder remaining in the composite particles was removed by alcohol.
To the obtained composite particle group, 1 wt% of a silicone resin was added, mixed and dried. To the dry matter was added 0.1 wt% of a lubricating material (zinc stearate) and further mixed. 5g of the final mixture was filled in a metal mold coated with zinc stearate in advance, and pressed at a molding pressure of 980 MPa. Then, annealing was performed at 750 ℃ for 30 minutes in a nitrogen atmosphere to obtain a toroidal core as a dust core.
Comparative example 5
Composite particles were produced in the same manner as in example 1, except that the soft magnetic iron-based particles were the carbonyl iron powder of example 7, the weight ratio of the carbonyl iron powder to the BN powder was 1: 1, and the SiON powder was not used. A toroidal core of comparative example 5 was obtained in the same manner as in example 1, except that the molding pressure was set to 980MPa, and the annealing conditions were set to 750 ℃ for 30 minutes.
Comparative example 6
An alcohol solution containing 2 wt% of SiON powder and 1 wt% of phosphoric acid based on the weight of carbonyl iron powder was supplied to the carbonyl iron powder of example 7, and the alcohol was dried to form an iron phosphate coating layer containing a nano powder on the surface of the carbonyl iron powder. Thereafter, a toroidal core of comparative example 6 was obtained in the same manner as in example 7.
The conditions and results are shown in tables 1 and 2. The compositions of the compound of the coating layer and the nanopowder were confirmed by line analysis and point analysis performed by STEM-EDS. A thin chip sample was prepared from the powder core by FIB (Nova200i) manufactured by FEI of Japan and observed by STEM-EDS (JEM2100FCS) manufactured by JEOL. For the thickness of the coating layer, 10 points of 10 particles were measured, and the average value was determined.
With respect to the particle diameter of the nanoparticles, a TEM image of a cross section of the dust core was analyzed by QMP (ver.2.0.1) as free software, and measured as a diameter of a circle equal to the area of the particle, and an average value of 30 particles was obtained.
[ TABLE 1 ]
[ TABLE 2 ]
In examples 1 to 7, toroidal cores capable of achieving both high specific permeability and low magnetic loss were obtained. On the other hand, in comparative examples 1 to 7, the specific magnetic permeability was not sufficiently high.
Claims (6)
1. A powder magnetic core, comprising:
a plurality of soft magnetic iron-based particles;
coating layers provided on the surfaces of the soft magnetic iron-based particles, respectively;
a sandwiched layer disposed between the cladding layers; and
a nano-powder disposed between the soft magnetic iron-based particles,
the clad layer is a layer containing a compound of Fe, Si, O, B and N,
the nano powder is powder containing at least one element selected from Fe, Si, Zr, Co, Al, Mg, Mn and Ni, and a compound of O and N.
2. The powder magnetic core of claim 1, wherein:
the nano powder is powder containing compounds of Fe, Si, O and N.
3. The powder magnetic core according to claim 1 or 2, wherein:
the average particle size of the nano powder is 10-200 nm.
4. The powder magnetic core according to claim 1 or 2, wherein:
the average thickness of the coating layer is 1-100 nm.
5. The powder magnetic core according to claim 1 or 2, wherein:
the average particle diameter of the soft magnetic iron-based particles is 1 to 100 [ mu ] m.
6. The powder magnetic core according to claim 1 or 2, wherein:
the soft magnetic iron-based particles are Fe-Si alloy particles, and the apparent density of the dust core is 6.6g/cm3The above.
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