JP4903101B2 - High specific resistance and low loss composite soft magnetic material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a high specific resistance and low loss composite soft magnetic material used as a material for various electromagnetic circuit components such as a motor, an actuator, a reactor, a transformer, a choke core, and a magnetic sensor core, and a method for manufacturing the same.

  Conventionally, as magnetic core materials for motors, actuators, magnetic sensors, etc., iron powder, Fe-Al iron-based soft magnetic alloy powder, Fe-Ni iron-based soft magnetic alloy powder, Fe-Cr iron-based soft magnetic alloy powder Soft magnetic sintered material obtained by sintering Fe-Si based iron-based soft magnetic alloy powder, Fe-Si-Al based iron-based soft magnetic alloy powder (hereinafter collectively referred to as soft magnetic metal particles) It has been known. This type of soft magnetic sintered material has a high magnetic flux density but a low specific resistance, which has a problem of poor high frequency characteristics. Therefore, in order to increase the specific resistance and improve the high frequency characteristics, a dust soft magnetic material in which soft magnetic metal particles are bonded with water glass or low-melting glass has been proposed (see Patent Document 1 or Patent Document 2).

  However, the composite soft magnetic sintered material obtained by bonding the soft magnetic metal particles with water glass or low melting glass has poor adhesion between the soft magnetic metal particles and water glass or low melting glass. In order to secure strength by bonding with water glass or low melting glass, it must be mixed with a large amount of water glass or low melting glass to such an extent that soft magnetic metal particles are dispersed in water glass or low melting glass. The powder soft magnetic material obtained by using a large amount of water glass or low-melting glass in this way has a large specific resistance, but the magnetic flux density is extremely reduced, and various electronic devices such as motors, actuators, magnetic sensor magnetic cores, etc. There was a problem that it could not be used as a material for parts.

Therefore, for the purpose of achieving both high magnetic flux density and high specific resistance, a soft magnetic metal particle phase and a grain boundary phase surrounding the soft magnetic metal particle phase, the grain boundary phase has a hexagonal crystal structure, a ZnO type phase and a cubic crystal structure. A ZnO type phase having the hexagonal crystal structure is dispersed in contact with the soft magnetic metal particle phase, and the glass phase has the cubic crystal structure. A structure in which a mixed oxide phase of Fe and Zn is dispersed in contact with the ZnO-type phase, and the glass phase is sandwiched and dispersed in contact with the mixed oxide phase of Fe and Zn having the cubic structure A composite soft magnetic sintered material having the following is provided. (See Patent Document 3)
On the other hand, Mg-containing iron oxide coated iron powder coated with Mg-containing ferrite film by chemical method such as chemical plating or coating method is mixed with low melting point glass powder, then compacted, heat treated and powdered magnetic material A method of manufacturing is also known. (See Patent Document 4)
JP-A-5-258934 JP 63-158810 A JP 2004-253787 A JP 2004-297036 A

According to the composite soft magnetic sintered material described in Patent Document 3, there is a problem that the mixed oxide phase of Fe and Zn is decomposed when heated at a temperature exceeding 600 ° C. However, since the glass powder described in Patent Document 3 is not melted by firing at a temperature at which this decomposition does not occur, for example, firing at 600 ° C., the binding property between the soft magnetic metal particle phases is increased. It was difficult to obtain a high strength soft magnetic composite compacted fired material.
In addition, when glass powder is added to zinc oxide-coated soft magnetic metal particles and molded, friction between the glass powder and zinc oxide coating (insulating layer) occurs, and the zinc oxide coating is easily damaged. It was difficult to obtain a soft magnetic composite compacted fired material.

  On the other hand, in the soft magnetic composite compacted calcined material obtained by compacting the Mg-containing iron oxide-coated iron powder, the ferrite film is not formed because the surface of the soft magnetic metal particles is coated with the Mg-containing ferrite film by a chemical method. It becomes stable and changes in insulation, and the adhesion of the Mg-containing ferrite film to the surface of the soft magnetic metal particles is not sufficient, and the Mg-containing iron oxide film-coated powder is fired after being press-molded with a low-melting glass. However, there is a possibility that a soft magnetic composite compacted fired material having sufficient strength cannot be provided.

  The present invention was devised in view of the above problems, and its purpose is to provide a structure with an excellent MgO film that can be fired at 600 ° C. or higher, for example, 7000 ° C. While maintaining low coercive force by strain relief annealing at the above temperature, the interface connecting soft magnetic metal particles has high specific resistance between the silicone resin, low melting point glass or metal oxide component and Mg-containing oxide coating layer. An object of the present invention is to provide a high specific resistance, low loss composite soft magnetic material having an excellent low iron loss and mechanical strength by forming a component wustite compound layer of Mg-Fe-binder component-O and a method for producing the same.

The present inventors conducted research on Fe-based soft magnetic sintered materials and provided Mg-containing oxide-coated soft magnetic powder as an example of a technique that is less likely to break the insulating coating even during compaction molding. is doing.
That is, by heating an Fe-based soft magnetic powder in an oxidizing atmosphere in advance, an oxidized soft magnetic powder in which an iron oxide film is formed on the surface of the soft magnetic powder is produced, and Mg powder is added to the oxidized soft magnetic powder. Addition and heating the mixed powder obtained by mixing with a granulation rolling agitation and mixing device in an inert gas atmosphere or vacuum atmosphere, and further heating in an oxidizing atmosphere as necessary It is a soft magnetic powder obtained by the technology of applying. According to this technique, Mg—Fe—O ternary elements such as (Mg, Fe) O and (Mg, Fe) ₃ O ₄ represented by the generally known MgO—FeO—Fe ₂ O ₃ system. Among various oxides of the series, it is possible to obtain an Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O formed on the surface of the soft magnetic powder particles.

In the Mg-containing oxide-coated soft magnetic powder in which the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O is formed on the surface of the Fe-based soft magnetic powder, Since the adhesion of the oxide film to the soft magnetic powder is much better than the conventional material, the oxide film that is an insulating film is less likely to be destroyed during compaction molding, and the oxide film is composed of Fe-based soft magnetic powders. Therefore, even if high temperature strain relief firing is performed after compaction molding, the insulating properties of the oxide film are not lowered, and a high specific resistance can be maintained, resulting in low eddy current loss and further strain relief. Since the coercive force can be reduced after firing, the hysteresis loss can be kept low, and thus a low-loss soft magnetic composite compacted fired material can be obtained.
The inventors of the present invention paid attention to this technique and studied a compacting material obtained by compacting the above-mentioned Mg-containing oxide-coated soft magnetic powder, and reached the present invention.

(1) In order to achieve the above object, the high specific resistance and low loss composite soft magnetic material of the present invention comprises an Fe-based soft magnetic metal particle and a Mg film having a thickness of 20 to 200 nm coated on the surface of the soft magnetic metal particle. Mg-containing oxide-coated soft magnetic particles comprising an oxide-containing oxide film and heat-treated in a non-oxidizing atmosphere at 800 to 1000 ° C. are composed of a silicon compound, an Mg-containing oxide film, a low-melting glass, and an Mg-containing oxide. object film, or a grain boundary layer of a composite compound of any binder for the metal oxide and the Mg-containing oxide film, the soft by compaction firing of the said binder Mg-containing oxide-coated soft-magnetic particles A plurality of bonds are formed through a grain boundary layer including a wustite phase having Fe diffused from magnetic metal particles .
(2) In order to achieve the above object, the high resistivity low loss composite soft magnetic material of the present invention is such that the grain boundary layer described in (1) has a position near 36 degrees in the X-ray diffraction peak by the 2θ method. It is a grain boundary layer having a wustite phase having a peak at a position near 42 degrees and in which Fe is dispersed in an amount of 10 to 20 at% .
(3) In order to achieve the above object, in the high specific resistance, low loss composite soft magnetic material of the present invention, the binder is any one of a silicone resin, a low melting glass, and a metal oxide, and the grain boundary is formed by the firing. The layer includes at least a compound comprising a silicon compound, an Mg-containing oxide and Fe, a low melting glass, a compound comprising an Mg-containing oxide and Fe, or a compound comprising a metal oxide, an Mg-containing oxide and Fe, and a wustite phase. The grain boundary layer is included .

(4) In order to achieve the above object, in the high specific resistance, low loss composite soft magnetic material of the present invention, the Fe-based soft magnetic metal particles are Fe, and at least one of Si, Al, Ni, Cr, and V. It is characterized by adding more than seeds .
(5) In order to achieve the above object, the high resistivity and low loss composite soft magnetic material of the present invention is characterized in that the silicon compound is a Si—O—C compound .
(6) In order to achieve the above object, in the high resistivity low loss composite soft magnetic material of the present invention, the low melting point glass is Bi ₂ O ₃ —B ₂ O ₃ , SnO—P ₂ O ₅ , SiO ₂ —B. ₂ O ₃ —ZnO, SiO ₂ —B ₂ O ₃ —R ₂ O (R is an alkaline earth metal), or Li ₂ O—ZnO.
(7) In order to achieve the above object, the high resistivity low loss composite soft magnetic material of the present invention is such that the metal oxide is V ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , Sb ₂ O ₃ , MoO. It is any one of ₂ .
(8) In order to achieve the above object, the high resistivity low loss composite soft magnetic material of the present invention is characterized in that the non-oxidizing atmosphere is any one of a vacuum atmosphere, an argon gas atmosphere, and a hydrogen atmosphere. .

(9) In order to achieve the above object, the method for producing a high resistivity and low loss composite soft magnetic material of the present invention comprises Fe-based soft magnetic metal particles and a film thickness of 20 to 20 coated on the surface of the soft magnetic metal particles. After heat-treating Mg-containing oxide-coated soft magnetic particles comprising a 200-nm Mg-containing oxide film at 800 to 1100 ° C. in any non-oxidizing atmosphere of hydrogen atmosphere, vacuum atmosphere, and argon atmosphere, Heat-treated Mg-containing oxide-coated soft magnetic particles are mixed and consolidated by mixing at least one of silicone resin, low melting point glass, and metal oxide as a binder, vacuum atmosphere, argon atmosphere, air, nitrogen atmosphere And diffusing from the component of the binder, the component of the Mg-containing oxide film, and the soft magnetic metal particles by firing in any one of hydrogen atmospheres made of a composite compound with e, characterized by a plurality formed by bonding sintered body the Mg-containing oxide-coated soft-magnetic particles through the grain boundary layer having a wustite phase.

(10) In order to achieve the above object, the method for producing a high specific resistance, low loss composite soft magnetic material of the present invention uses a position near 36 degrees and 42 degrees in the X-ray diffraction peak by the 2θ method as the grain boundary layer. A grain boundary layer having a wustite phase having a peak at a position and Fe dispersed in an amount of 10 to 20 at% is characterized.
(11) In order to achieve the above object, in the method for producing a high specific resistance, low loss composite soft magnetic material of the present invention, the binder is mainly composed of any one of a silicone resin, a low melting glass, and a metal oxide. , The grain boundary layer by the firing is a compound comprising at least a silicon compound, an Mg-containing oxide and Fe, a low melting point glass, a compound comprising an Mg-containing oxide and Fe, a compound comprising a metal oxide, an Mg-containing oxide and Fe One of these is characterized by containing a wustite phase .
(12) In order to achieve the above object, the method for producing a high resistivity and low loss composite soft magnetic material of the present invention is characterized in that the binder is a Si-O-C compound .

(13) In order to achieve the above object, in the method for producing a high specific resistance, low loss composite soft magnetic material of the present invention, the low melting point glass is made of Bi ₂ O ₃ —B ₂ O ₃ , SnO—P ₂ O ₅ , SiO _2. It is characterized by being any one of _2- B ₂ O ₃ —ZnO, SiO ₂ —B ₂ O ₃ —R ₂ O (R is an alkaline earth metal), and Li ₂ O—ZnO .
(14) In order to achieve the above object, in the method for producing a high specific resistance, low loss composite soft magnetic material of the present invention, the metal oxide is changed to V ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , Sb ₂ O. _3, characterized by either of MoO _2.
(15) In order to achieve the above object, the high resistivity and low loss composite soft magnetic material manufacturing method of the present invention includes Fe, Si, Al, Ni, Cr, and V as Fe-based soft magnetic metal particles. Among them, a material obtained by adding at least one kind is used .

In the production method of the present invention, Fe-based soft magnetic metal particles and an Mg-containing oxide coating film coated on the surface of the soft magnetic metal particles can be formed with good adhesion, and further Mg-containing Fe-based soft magnetic metal particles provided with an oxide coating film are mixed in the grain boundary layer as described above as a binder, silicon compound, low melting point glass, metal oxide and Mg-containing oxidation Bonding is performed at the composite compound grain boundary layer formed by diffusion growth of the elements of the material coating film, and iron is also distributed and grown at the grain boundary of the joint part, so that the high specific resistance and the low specific resistance are low. A lossy composite soft magnetic material can be obtained.
Moreover, the Mg-containing oxide coating film can be reliably present around the Fe-based soft magnetic metal particles even after the compacting, so that a high specific resistance can be obtained and a high specific resistance with low eddy current loss. A low-loss composite soft magnetic material can be obtained.
Furthermore, the Mg-containing oxide-coated soft magnetic particles having the Mg-containing oxide film are heat-treated at 800 to 1100 ° C. in a non-oxidizing atmosphere, so that the Mg-containing oxide films that are not easily fixed can be bonded to each other. It adheres as a wustite phase containing ingredients.

  Since the high specific resistance and low loss composite soft magnetic material obtained by the manufacturing method of the present invention has high density, high specific resistance and high magnetic flux density, the soft magnetic composite compacted fired material of the present invention has high magnetic flux density and It is excellent because it has the characteristics of high-frequency and low iron loss, and can be used as a material for various electromagnetic circuit components that make use of these characteristics.

The electromagnetic circuit component can be used as, for example, a magnetic core, a motor core, a generator core, a solenoid core, an ignition core, a reactor core, a transformer core, a choke coil core, a magnetic sensor core, etc. It is possible to provide an electromagnetic circuit component that can exhibit the above.
Electric devices incorporating these electromagnetic circuit components include motors, generators, solenoids, injectors, electromagnetically driven valves, inverters, converters, transformers, relays, magnetic sensor systems, etc. There is an effect that performance and size and weight can be reduced.

In the present invention, first, Mg-containing oxide-coated soft magnetic particles (powder) in which a Mg—Fe—O ternary oxide deposition film containing (Mg, Fe) O is coated on the surface of soft magnetic metal particles are produced. To do.
In order to obtain the coated soft magnetic metal particles, the following various raw material powders may be used by selecting one of the methods described in (A) to (D) described later.
Fe-based soft magnetic metal particles as a raw material powder used in the method for producing Mg-containing oxide-coated soft magnetic metal particles of the present invention are conventionally known iron powder, insulated iron powder, Fe-Al based iron. -Based soft magnetic alloy powder, Fe-Ni-based iron-based soft magnetic alloy powder, Fe-Cr-based iron-based soft magnetic alloy powder, Fe-Si-based iron-based soft magnetic alloy powder, Fe-Si-Al-based iron-based soft magnetic alloy Preferably, it is a powder, Fe-Co iron-based soft magnetic alloy powder, Fe-Co-V iron-based soft magnetic alloy powder or Fe-P iron-based soft magnetic alloy powder.
More specifically, the iron powder is a pure iron powder, and the insulation-treated iron powder is a phosphate-coated iron powder or a wet solution such as a silica sol-gel solution (silicate) or an alumina sol-gel solution. This is a silicon oxide or aluminum oxide coated iron powder that is coated on the surface of the iron powder and then dried and fired. The Fe—Al-based iron-based soft magnetic alloy powder contains A1: 0.1 to 20%, and the balance is Fe. And an Fe—Al-based iron-based soft magnetic alloy powder (for example, an alpalm powder having a composition of Fe-15% Al) made of inevitable impurities.

Further, the Fe—Ni-based iron-based soft magnetic alloy powder contains Ni: 35 to 85%, and Mo: 5% or less, Cu: 5% or less, Cr: 2% or less, Mn: 0.5 if necessary. % Nickel-based soft magnetic alloy powder (for example, Fe-49% Ni powder) containing one or two or more of Fe and inevitable impurities, and Fe-Cr-based iron-based soft magnetism The alloy powder contains Cr: 1-20%, and if necessary, contains Al: 5% or less, Nil 5% or less, one or two of them, the balance being Fe-Cr based on Fe and inevitable impurities This is an iron-based soft magnetic alloy powder, and the Fe-Si-based iron-based soft magnetic alloy powder contains Si: 0.1 to 10%, and the balance is Fe-Si-based iron-based soft magnetic alloy composed of Fe and inevitable impurities. A powder is preferred.
The Fe-Si-Al-based iron-based soft magnetic alloy powder contains Si: 0.1 to 10%, Al: 0.1 to 20%, and the balance is Fe-Si-Al composed of Fe and inevitable impurities. Iron-based soft magnetic alloy powder, Fe-CV-based iron-based soft magnetic alloy powder contains C: 0.1-52%, V: 0.1-3%, the balance is Fe and inevitable Fe-Co-V iron-based soft magnetic alloy powder made of impurities, Fe-C iron-based soft magnetic alloy powder contains C: 0.1-52%, the balance consists of Fe and inevitable impurities Fe-Co-based iron-based soft magnetic alloy powder, Fe-P-based iron-based soft magnetic alloy powder contains P: 0.5 to 1%, the balance is Fe-P-based iron consisting of Fe and inevitable impurities It is preferably a base soft magnetic alloy powder (wherein% indicates mass%).

  These Fe-based soft magnetic metal particles are preferably soft magnetic metal particles having an average particle size in the range of 5 to 500 μm. The reason is that if the average particle size is less than 5 μm, the compressibility of the powder is lowered, and the volume ratio of the soft magnetic metal particles is lowered, so the value of the magnetic flux density is lowered. If it is larger than 500 μm, the eddy current inside the soft magnetic metal particles increases and the magnetic permeability at high frequency decreases.

(A) It is obtained by using any one of these various soft magnetic metal particles as a raw material powder and subjecting it to an oxidation treatment in which it is maintained at room temperature to 500 ° C. in an oxidizing atmosphere, and then adding and mixing Mg powder to this raw material powder. The mixed powder was heated in an inert gas atmosphere or a vacuum atmosphere at a temperature of 150 to 1100 ° C. and a pressure of 1 × 10 ⁻¹² to 1 × 10 ⁻¹ MPa, and further in an oxidizing atmosphere if necessary, a temperature of 50 When heated at ˜400 ° C., Mg-containing oxide-coated soft magnetic particles (powder) having an oxide insulating film containing Mg on the surface of the soft magnetic metal particles are obtained.
The Mg-containing oxide-coated soft magnetic particles have much better adhesion than the conventional Mg-containing oxide-coated soft magnetic particles formed with an Mg ferrite film. Even if the green compact is produced by press molding, the insulating coating is less likely to break and peel off, and the green compact of the Mg-containing oxide-coated soft magnetic particles is obtained by firing at a temperature of 400 to 1300 ° C. The resulting soft magnetic composite compacted fired material has a structure in which the Mg-containing oxide film is uniformly dispersed at the grain boundaries, and the Mg-containing oxide film is not concentrated and dispersed at the grain boundary triple points.

In the case of the above-mentioned production method, oxidized soft magnetic metal particles are used as raw material powder, and mixed powder obtained by adding and mixing Mg powder to this raw material powder is temperature: 150 to 1100 ° C., pressure: 1 × 10 ^{− In order} to heat in an inert gas atmosphere or a vacuum atmosphere of ¹² to 1 × 10 ⁻¹ MPa, it is preferable to heat the mixed powder while rolling.

  (B) After adding and mixing the silicon monoxide powder to the oxide-coated soft magnetic powder in which an oxide is formed on the surface of the soft magnetic powder by maintaining the soft magnetic metal particles in an oxidizing atmosphere at room temperature to 500 ° C. Alternatively, heating is performed in a vacuum atmosphere with mixing at a temperature of 600 to 1200 ° C., and further, after adding and mixing Mg powder or heating in a vacuum atmosphere with mixing at a temperature of 400 to 800 ° C. An Mg-Si-containing oxide-coated soft magnetic powder in which an Mg-Si-containing oxide film is formed on the surface of the soft magnetic powder is obtained, and is produced using the Mg-Si-containing oxide-coated soft magnetic powder produced by this method. The composite soft magnetic sintered material is higher in density and bending strength than the composite soft magnetic sintered material obtained by compression molding and sintering a mixture of a compound that generates SiO and MgCO or MgO. Resistivity and magnetic flux density is excellent.

(C) A silicon monoxide powder and an Mg powder in an oxide-coated soft magnetic powder in which an iron oxide film is formed on the surface of the soft magnetic metal particles by maintaining the soft magnetic metal particles in an oxidizing atmosphere at room temperature to 500 ° C. Are added and mixed at the same time, or when mixed and heated in a vacuum atmosphere at a temperature of 400 to 1200 ° C., Mg—Si-containing oxide film is formed on the surface of the soft magnetic metal particles. Si-containing oxide-coated soft magnetic powder is obtained. The composite soft magnetic sintered material produced using the Mg-Si-containing oxide-coated soft magnetic powder produced by this method is a compression molding of a conventional mixture of a compound that generates SiO ₂ and MgCO ₃ or MgO powder. The density, bending strength, specific resistance, and magnetic flux density can be made superior to the composite soft magnetic sintered material obtained by sintering.
(D) Mg powder was added to and mixed with the oxide-coated soft magnetic powder in which an iron oxide film was formed on the surface of the soft magnetic metal particles by maintaining the soft magnetic metal particles in an oxidizing atmosphere at room temperature to 500 ° C. When heated at a temperature of 400 to 800 ° C. in a vacuum atmosphere after or while mixing, an Mg-containing oxide-coated soft magnetic powder in which an Mg-containing oxide film is formed on the surface of the soft magnetic powder is obtained.
After adding silicon monoxide powder to the Mg-containing oxide-coated soft magnetic powder and mixing it or heating it in a vacuum atmosphere while mixing, the temperature is maintained at 600 to 1200 ° C., and the surface of the soft magnetic powder is coated with Mg. -A composite soft magnetic sintered material produced using an Mg-Si-containing oxide-coated soft magnetic powder obtained by this method, wherein an Mg-Si-containing oxide-coated soft magnetic powder having a Si-containing oxide film formed thereon is obtained If so, the density, bending strength, specific resistance and resistance are higher than those of a composite soft magnetic sintered material obtained by compression molding and sintering a mixture of a compound that generates SiO ₂ and MgCO ₃ or MgO powder. Magnetic flux density can be improved.
The addition amount of the silicon monoxide powder is preferably in the range of 0.01 to 1% by mass, and the addition amount of the Mg powder is preferably in the range of 0.05 to 1% by mass.
The vacuum atmosphere is preferably a vacuum atmosphere at a pressure of 1 × 10 ⁻¹² to 1 × 10 ⁻¹ MPa.

The silicon monoxide (SiO) powder used in the above production method is an oxide having the highest vapor pressure among silicon oxides. Therefore, it is easy to deposit a silicon oxide component on the surface of soft magnetic metal particles by heating. Even if silicon dioxide (SiO ₂ ) powder having a low pressure is mixed and heated, a silicon oxide film having a sufficient thickness may not be formed on the surface of the soft magnetic metal particles. After the silicon monoxide (SiO) powder is added to the oxide-coated soft magnetic powder and mixed, or in a vacuum atmosphere with mixing, the temperature is maintained at 600 to 1200 ° C., so that SiOx (however, x: 1-2) A silicon oxide film-coated soft magnetic powder having a film formed thereon was formed, and when Mg powder was further added to the silicon oxide film-coated soft magnetic powder and heated in a vacuum atmosphere while mixing, Mg-Si- An Mg—Si-containing oxide-coated soft magnetic powder in which an Mg—Si-containing oxide film made of Fe—O is coated on a soft magnetic powder is obtained.

  The above oxide-coated soft magnetic powder is produced by forming an iron oxide film on the surface of the soft magnetic powder by maintaining the soft magnetic metal particles in an oxidizing atmosphere (for example, in the air) at a temperature of room temperature to 500 ° C. can do. This iron oxide film has the effect of improving the coverage of SiO and / or Mg. When an oxide-coated soft magnetic powder is produced and heated above 500 ° C. in an oxidizing atmosphere, the soft magnetic metal particles agglomerate to form an aggregate of soft magnetic metal particles, which can be uniformly sintered. It is not preferable because the surface cannot be oxidized. Therefore, the heating temperature during the production of the oxide-coated soft magnetic powder was set to room temperature to 500 ° C. A more preferred range is from room temperature to 300 ° C. More preferably, the oxidizing atmosphere is a dry oxidizing atmosphere.

  In the Mg—Si-containing oxide-coated soft magnetic powder used in the present invention, the amount of SiO powder added to the oxide-coated soft magnetic powder is limited to 0.01 to 1% by mass. If it is less than 01% by mass, the thickness of the silicon oxide film formed on the surface of the oxide-coated soft magnetic powder is insufficient, so the amount of Si contained in the Mg-Si-containing oxide film is insufficient, and therefore the specific resistance is high. An Mg-Si-containing oxide film cannot be obtained, which is not preferable. On the other hand, if it exceeds 1% by mass, the thickness of the SiOx (x; 1-2) silicon oxide film to be formed becomes too thick. There is a possibility that the density of the soft magnetic composite compacted fired material obtained by compacting and firing the Mg-Si-containing oxide-coated soft magnetic metal particles may be lowered.

  Moreover, in the manufacturing method of Mg-Si containing oxide covering soft magnetic powder of this invention, the addition amount of Mg powder was limited to 0.05-1 mass%, the addition amount of Mg powder was 0.05 mass% Is less than the thickness of the Mg film formed on the surface of the oxide-coated soft magnetic powder, the amount of Mg contained in the Mg-Si-containing oxide film is insufficient. Since an oxide film cannot be obtained, it is not preferable. On the other hand, when it exceeds 1% by mass, the formed Mg film becomes too thick, and the obtained Mg-Si-containing oxide-coated soft magnetic powder is reduced. This is because the density of the soft magnetic composite compacted fired material obtained by compacting and firing becomes undesirably low.

In the method for producing an Mg-Si-containing oxide-coated soft magnetic powder used in the present invention, the conditions for adding and mixing SiO powder, Mg powder, or a mixed powder of SiO powder and Mg powder to the oxide-coated soft magnetic powder are set at a temperature of 600 to The reason why the vacuum atmosphere is 1200 ° C. is that a SiO film having a sufficient thickness or an Mg—Si-containing oxide film cannot be obtained even when heated below 600 ° C. because the vapor pressure of SiO is small. This is because mixing above 1200 ° C. is not preferable because the soft magnetic powder is sintered and the desired Mg—Si-containing oxide-coated soft magnetic powder cannot be obtained. Further, the heating atmosphere at that time is preferably in a vacuum atmosphere at a pressure of 1 × 10 ⁻¹² to 1 × 10 ⁻¹ MPa, and more preferably heated while rolling.

The soft magnetic metal particles used when producing the oxide-coated soft magnetic powder are preferably soft magnetic powders having an average particle size in the range of 5 to 500 μm. The reason is that if the average particle size is less than 5 μm, the compressibility of the powder is lowered, and the volume ratio of the soft magnetic powder is lowered, so the value of the magnetic flux density is lowered. If it is larger than 500 μm, the eddy current inside the soft magnetic powder increases and the magnetic permeability at high frequency decreases.
The oxidation treatment of the soft magnetic metal particles has an effect of improving the coverage of Mg, and is performed by maintaining the temperature at 50 to 100 ° C. in an oxidizing atmosphere at a temperature of 150 to 500 ° C. or distilled water or pure water. In this case, it is not efficient when the temperature is less than 50 ° C., and on the other hand, if the temperature exceeds 500 ° C. in an oxidizing atmosphere, sintering occurs, which is not preferable. More preferably, the oxidizing atmosphere is a dry oxidizing atmosphere.

  The term “deposited film” usually indicates a film in which atoms constituting a film deposited by vacuum evaporation or sputtering are deposited on a substrate, for example. The deposited film used in the present invention is an Fe-based soft magnetic film having an iron oxide film. A film in which powdered iron oxide (Fe—O) and Mg are deposited on the surface of the Fe-based soft magnetic metal particles with a reaction is shown. The film thickness of the Mg-Fe-O ternary oxide deposited film formed on the surface of the Fe-based soft magnetic metal particles is such that the high magnetic flux density and high specific resistance of the soft magnetic composite compacted fired material after compacting are reduced. In order to obtain it, it is preferable to exist in the range of 5 nm-500 nm. If the film thickness is less than 5 nm, the specific resistance of the compacted soft magnetic composite compacted fired material is not sufficient, and eddy current loss increases. Since the magnetic flux density of the powder-molded soft magnetic composite compacted fired material is lowered, it is not preferable. In such a range, a more preferable film thickness is in the range of 20 to 200 nm.

  The Mg-containing oxide-coated soft magnetic particles produced by the above-described method have an Mg-containing oxide film formed on the surface thereof, and this Mg-containing oxide film reacts with silicon oxide or aluminum oxide to form a composite oxide. In order to finally obtain a soft magnetic composite compacted fired material having a high specific resistance in which a composite oxide having a high resistance is interposed at the grain boundary of the soft magnetic powder and to be sintered through silicon oxide or aluminum oxide A soft magnetic composite compacted fired material having excellent mechanical strength can be produced. In this case, the coercive force can be kept small from being sintered mainly with silicon oxide or aluminum oxide, and thus a soft magnetic composite compacted fired material with less hysteresis loss can be produced. In an inert gas atmosphere or a non-oxidizing gas atmosphere, the temperature is preferably 400 to 1300 ° C.

"Production method of soft magnetic composite compacted fired material"
In order to produce a high resistivity and low loss composite soft magnetic material using the Mg-containing oxide-coated soft magnetic particles prepared as described above by the method described above, first, the Mg-containing oxide coating prepared by the method described above is used. The soft magnetic particles are heated in a non-oxidizing atmosphere, preferably in a hydrogen atmosphere at 800 to 1000 ° C., and then mixed with a silicone resin, a low-melting glass or a metal oxide as a binder material. A high resistivity and low loss composite soft magnetic material can be obtained by compacting by a normal method and then firing at 500 to 1000 ° C. in an argon atmosphere, a nitrogen atmosphere, a hydrogen atmosphere or the air.

The low melting point glass is Bi ₂ O ₃ —B ₂ O ₃ , SnO—P ₂ O ₅ , SiO ₂ —B ₂ O ₃ —ZnO, SiO ₂ —B ₂ O ₃ —R ₂ O (R is an alkaline earth metal) ), Li ₂ O—ZnO can be used. These addition amounts can be in the range of 0.2 to 1.5 mass%.
Alternatively, one or more metal oxides of aluminum oxide, boron oxide, vanadium oxide, bismuth oxide, antimony oxide, and molybdenum oxide are added to Mg-containing oxide-coated soft magnetic particles with B ₂ O ₃ , V _{2. O 5, Bi 2 O 3,} Sb 2 O 3, mixed with MoO ₃ in the range of 0.05 to 1 mass% in terms of dust after mixing, molding, temperature 500 to the resulting powder compact A high specific resistance and low loss composite soft magnetic material can be produced by firing at 1000 ° C. in vacuum, argon atmosphere, nitrogen atmosphere, hydrogen atmosphere, or air. The firing atmosphere is desirably a nitrogen atmosphere or a hydrogen atmosphere, and a hydrogen atmosphere is particularly preferable.
The low-melting glass and metal oxide to be mixed as the binder may be in a powder state, and a precursor solution such as a sol-gel solution or a metal organic substance can also be used.

As described above, in the present invention, the surface portion of the Mg-containing oxide-coated soft magnetic particles is activated by heat-treating the Mg-containing oxide-coated soft magnetic particles at a temperature of 800 to 1000 ° C. in a hydrogen atmosphere. This can promote the formation of a compound with the binder component during firing.
For the Mg-containing oxide-coated soft magnetic particles (powder) in which the oxide-deposited film containing (Mg, Fe) O is formed on the surface of the soft magnetic metal particles, the oxide-deposited film containing (Mg, Fe) O is Although it is a deposited film mainly composed of a wustite phase, when heated at 800 to 1000 ° C. in a non-oxidizing atmosphere, the outermost surface portion of the deposited film becomes a clear wustite phase containing (Mg, Fe) O, and is more active. From this, it diffuses into the binder layer during firing to form a grain boundary layer mainly composed of a wustite phase composed of Mg, Fe, a binder component, and O. For example, when the binder is a silicone resin, the grain boundary layer can form a grain boundary compound mainly composed of a wustite phase composed of Mg, Si, O, Fe, and C to increase the specific resistance.

  The high specific resistance and low loss composite soft magnetic material obtained by the above-described method is such that the bond through the grain boundary layer of the plurality of Mg-containing oxide-coated soft magnetic particles is the soft magnetic metal particles and the soft magnetic metal particles. A bond obtained by a mixed compaction heat treatment of Mg-containing oxide-coated soft magnetic particles comprising a Mg-containing oxide film coated on the surface of the binder and a binder component such as the low-melting glass or metal oxide described above. Yes, the iron oxide present in the grain boundary layer between the Mg-containing oxide-coated soft magnetic particles, the Fe component is precipitated from the soft magnetic metal particles to the grain boundary and is oxide-dispersed and grown. The Mg-containing oxide film adjacent to the grain boundary layer is obtained from the Mg-containing oxide film provided in the Mg-containing oxide-coated soft magnetic particles before the mixed consolidation firing process.

The high specific resistance and low loss composite soft magnetic material obtained by the above manufacturing method has high density, high strength, high specific resistance and high magnetic flux density. Since it has the characteristics of high frequency and low iron loss in terms of density, it can be used as a material for various electromagnetic circuit components that take advantage of this characteristic.
Further, in the high resistivity and low loss composite soft magnetic material obtained by the above manufacturing method, it exists at the interface between the Mg—Fe—O ternary oxide deposited film containing (Mg, Fe) O and its interface. Since it has a grain boundary layer in which a binder component such as low-melting glass or metal oxide is diffused, the Mg-containing oxide-coated soft magnetic particles are particularly well-bonded and have high specific resistance and eddy currents. It is possible to obtain a high resistivity and low loss composite soft magnetic material with low loss and excellent soft magnetic properties with low iron loss.

A soft magnetic powder (pure iron powder) having a particle size of 100 μm was subjected to heat treatment at 220 ° C. in the atmosphere for 10 to 60 minutes. Here, the Mg-containing oxide film is proportional to the oxide film thickness generated by the heat treatment in the air at 220 ° C. in the previous stage. Next, the addition amount of Mg may be the minimum necessary, and 0.1 to 0.3% by mass of Mg powder is blended with respect to the iron powder, and this blended powder is granulated, tumbled and stirred in a vacuum atmosphere. To produce Mg-containing oxide-coated soft magnetic particles (hereinafter abbreviated as MgO film in Table 1).
Mg-Fe-O ternary oxide deposited film containing (Mg, Fe) O formed on the outer peripheral surface of the Mg-containing oxide-coated soft magnetic particle (hereinafter abbreviated as MgO film in Table 1) The results of measuring the film thickness are shown in Table 1. Since the film thickness is proportional to the oxide film thickness generated by the above-described heat treatment in the atmosphere, the MgO film thickness is preferably in the range of 20 to 200 nm, and more preferably in the range of MgO film thickness of 20 to 100 μm.

The Mg-containing oxide-coated soft magnetic particles provided with the MgO films having the respective film thicknesses were heat-treated at 800 to 1000 ° C. for 60 to 180 minutes in any one of a hydrogen atmosphere, a vacuum atmosphere, and an argon atmosphere.
In addition, as a conventional example, a sample not subjected to the above-described heat treatment at 800 to 1000 ° C. was prepared, and as a comparative example, a sample based on conditions deviating from the range desired in the present invention was also manufactured.
The used iron powder particle size (μm), Mg addition amount (% by mass), MgO film thickness (nm), and heat treatment conditions for the Mg-containing oxide-coated soft magnetic particles are shown in Table 1 below.

As shown in the following Table 2, 0.3 to 1.5% by mass of the silicone resin with respect to the Mg-containing oxide-coated soft magnetic particles produced under the conditions shown in Table 1 and the low-melting glass and the metal oxide in terms of oxides, respectively. Each was added in the range of 0.3 to 1.5% by mass, pressurized based on the molding pressure and firing conditions shown in Table 2, and fired to obtain a high resistivity and low loss composite soft magnetic material.
Table 2 shows the specific resistance, density, magnetic flux density, and iron loss at 1 T (Tesla) 400 Hz of the high specific resistance, low loss composite soft magnetic material thus manufactured.

As shown in Table 2, it is clear that the samples of Invention Examples 1 to 11 produced by satisfying the conditions specified in the present invention have excellent high specific resistance and excellent magnetic flux density, and have low iron loss. is there. These samples were also found to have high mechanical strength.
As is apparent from the results shown in Table 2, the specific resistance of the sample formed by compacting without heat treatment in the state of Mg-containing oxide-coated soft magnetic particles as in Conventional Examples 1, 2, and 3 is greatly reduced. Iron loss also increased. In addition, the specific resistance of the sample of Comparative Example 1 in which the temperature was too low at 700 ° C., the sample of Comparative Example 2 in which the temperature was too high at 1200 ° C., and the sample of Comparative Example 3 with a thin MgO film thickness was significantly low. Iron loss also increased. The sample of Comparative Example 4 was a sample in which the MgO film thickness was too large, but the iron loss increased although the specific resistance was slightly lower than that of the inventive example.

As a result of Auger spectroscopic analysis of the sample of Invention Example 1 for the grain boundary layer portion of the high resistivity and low loss composite soft magnetic material obtained using the silicone resin as a binder in the sample of the present invention, as an element constituting the grain boundary layer, mainly , Mg, O, Si were observed. Fe is often observed in the soft magnetic particle portion which is the main phase, Fe is also observed in the grain boundary layer portion, and it can be seen that Mg and O are widely dispersed in the grain boundary layer. It was found that there were many on the club side.
Results of Auger spectroscopic analysis of the sample of Invention Example 7 for the grain boundary layer portion of the high resistivity and low loss composite soft magnetic material obtained using Bi ₂ O ₃ —B ₂ O ₃ low melting point glass as a binder in the sample of the present invention As the elements constituting the grain boundary layer, Mg, O, B, and Bi were mainly observed. Fe is often observed in the soft magnetic particle portion which is the main phase, and is also observed in the grain boundary layer portion. It can be seen that Mg and O are widely dispersed in the grain boundary layer, and BiO and BO are in the grain boundary layer. It was found to be widely dispersed.

FIG. 1 shows the results of analyzing the grain boundary layer by an X-ray analysis apparatus in the samples of Invention Example 1 shown in Tables 1 and 2, and FIG. 1 shows the X-ray diffraction by the 2θ method measured before polishing the sample. FIG. 2 shows the measurement result of the X-ray diffraction peak by the 2θ method after sample polishing.
As shown in FIG. 1, small wustite peaks A and B are observed in the vicinity of 42 degrees between 2θ = 36 to 38 degrees and 2θ = 42 to 44 degrees, in addition to the four sharp large peaks of Fe. However, these peaks deviate from the original peak position of the wustite phase.
As shown in FIG. 2, the original peaks C and D of the wustite phase can be detected at a position near 2θ = 36 degrees and a position before 2θ = 42, in addition to the four sharp large peaks of Fe. From this measurement result, it was found that the grain boundary layer on the inner side of the sample was almost in the wustite phase.

FIG. 3 shows the result of line analysis performed on the grain boundary layer using an Auger electron spectrometer in the same sample, and FIG. 4 shows the result of converting the result shown in FIG. 3 into atomic concentration (at%).
It was found that in the grain boundary layer, the diffusion layer of Fe, which appears to have diffused Fe in the Mg-containing oxide-coated soft magnetic particles, was widely dispersed in the grain boundary layer at a low concentration of 10 to 20 at%. In addition, it can be said that there is a high-concentration layer of Mg having a predetermined thickness on the surface side of the Mg-containing oxide-coated soft magnetic particles, and that the Mg-containing oxide coating covers the periphery of the soft magnetic particles. It was found that a large amount is present in the central portion of the boundary layer, and that the content rapidly decreases as it approaches the soft magnetic particles.
From these facts, the grain boundary layer is a layer in which Mg, Si, O, and Fe exist, and a small amount of Fe and Si is diffused around the MgO-containing soft magnetic particles centering on MgO. It is considered that the Fe and Mg concentrations are low on the central side of the grain boundary layer, and the layer structure has a high Si and O concentration.

From the comparison of the X-ray analysis results and the line analysis results, the wustite phase on the sample surface becomes a wustite phase containing a binder component under the influence of heat treatment at 800 to 1100 ° C., compared to the wustite phase formed on the inner side of the sample. It can be presumed that the composition has been modified, for example, a wustite compound layer having a composition system of Mg-Fe- (binder component) -O is generated, and this improves the fixing strength in the grain boundary layer. As a result, it can be estimated that the overall mechanical strength of the high resistivity and low loss composite soft magnetic material has been improved.
Therefore, it was found that the sample according to the present invention is an excellent composite soft magnetic material that exhibits excellent low iron loss, extremely high specific resistance, excellent soft magnetic properties, and high mechanical strength.

The soft magnetic material according to the present invention can be used as an electromagnetic circuit component, for example, as a magnetic core, a motor core, a generator core, a solenoid core, an ignition core, a reactor core, a transformer core, a choke coil core, or a magnetic sensor core. In any case, the present invention can be applied to an electromagnetic circuit component that can exhibit excellent characteristics.
Electric devices incorporating these electromagnetic circuit components include motors, generators, solenoids, injectors, electromagnetically driven valves, inverters, converters, transformers, relays, magnetic sensor systems, etc. Increase performance and reduce size and weight.

FIG. 1 is an X-ray diffraction chart of a surface portion of a high specific resistance, low loss soft magnetic composite compacted fired material sample according to the present invention obtained in Examples. FIG. 2 is an X-ray diffraction chart showing the internal structure of the high resistivity, low loss soft magnetic composite compacted fired material sample according to the present invention obtained in the examples. FIG. 3 is a graph showing the results of X-ray line analysis of elements in the boundary layer of the high resistivity low loss composite soft magnetic material. FIG. 4 is a graph showing an element concentration distribution according to an X-ray line analysis result of elements in the boundary layer of the high resistivity low loss composite soft magnetic material.

Claims (15)

Fe-based soft magnetic metal particles and an Mg-containing oxide film with a thickness of 20 to 200 nm coated on the surface of the soft magnetic metal particles were provided, and heat treatment was performed in a non-oxidizing atmosphere at 800 to 1000 ° C. Mg-containing oxide-coated soft-magnetic particles, silicon compound and Mg-containing oxide film, a low-melting glass and Mg-containing oxide film, or a composite compound of any binder for the metal oxide and the Mg-containing oxide film A plurality of grain boundary layers bonded through a grain boundary layer including a wustite phase having Fe diffused from the soft magnetic metal particles by consolidation firing of the binder and the Mg-containing oxide-coated soft magnetic particles . A high resistivity, low loss composite soft magnetic material characterized by the above. The grain boundary layer is a grain boundary layer having a wustite phase having peaks at a position near 36 degrees and a position near 42 degrees in an X-ray diffraction peak by the 2θ method, and in which Fe is dispersed by 10 to 20 at%. The high specific resistance and low loss composite soft magnetic material according to claim 1. The binder is any one of a silicone resin, a low-melting glass, and a metal oxide, and the grain boundary layer is formed of at least a silicon compound, an Mg-containing oxide, and Fe by firing, and a low-melting glass and an Mg-containing oxide. 3. The high ratio according to claim 1, wherein a grain boundary layer containing a wustite phase is included in any one of a compound made of Fe and Fe, a metal oxide, an Mg-containing oxide, and a compound made of Fe. Low loss composite soft magnetic material. The Fe-based soft magnetic metal particles are obtained by adding at least one of Si, Al, Ni, Cr, and V to Fe. High resistivity low loss composite soft magnetic material. The high resistivity and low loss composite soft magnetic material according to claim 1, wherein the silicon compound is a Si—O—C compound . The low melting point glass is Bi ₂ O ₃ —B ₂ O ₃ , SnO—P ₂ O ₅ , SiO ₂ —B ₂ O ₃ —ZnO, SiO ₂ —B ₂ O ₃ —R ₂ O (R is an alkaline earth metal) ) Or Li ₂ O—ZnO . 5. The high specific resistance and low loss composite soft magnetic material according to claim 1. According to claim 1, wherein the metal oxide is either _{V 2 O 5, Al 2 O} 3, B 2 O 3, Sb 2 O 3, MoO 2 High resistivity low loss composite soft magnetic material.   The high specific resistance and low loss composite soft magnetic material according to any one of claims 1 to 7, wherein the non-oxidizing atmosphere is any one of a vacuum atmosphere, an argon gas atmosphere, and a hydrogen atmosphere. An Mg-containing oxide-coated soft magnetic particle comprising an Fe-based soft magnetic metal particle and an Mg-containing oxide film having a thickness of 20 to 200 nm coated on the surface of the soft magnetic metal particle is a hydrogen atmosphere, a vacuum atmosphere, After heat treatment at 800 to 1100 ° C. in any non-oxidizing atmosphere of the argon atmosphere , the heat-treated Mg-containing oxide-coated soft magnetic particles are converted into silicone resin, low-melting glass, and metal oxide, By mixing and compacting at least one kind as a binder, firing in any one of a vacuum atmosphere, an argon atmosphere, the air, a nitrogen atmosphere, and a hydrogen atmosphere,
The Mg-containing oxide-coated soft magnetic particles comprising a composite compound of the binder component, the Mg-containing oxide film component, and Fe diffused from the soft magnetic metal particles through a grain boundary layer having a wustite phase A method for producing a high specific resistance, low loss composite soft magnetic material, characterized in that a sintered body is formed by combining a plurality of. In the X-ray diffraction peak by the 2θ method, the grain boundary layer has a wustite phase having peaks at a position near 36 degrees and a position near 42 degrees, and is a grain boundary layer in which Fe is dispersed at 10 to 20 at%. The method for producing a high specific resistance, low loss composite soft magnetic material according to claim 9. The binder is mainly composed of any one of a silicone resin, a low-melting glass, and a metal oxide, and the grain boundary layer is formed of at least a silicon compound, a Mg-containing oxide, and Fe by the firing, and a low-melting glass. Mg-containing oxide and consisting of Fe compound, a high ratio of claim 9 or 10 characterized in that it contains wustite phase to one of the metal oxide and Mg-containing oxide and the compound of Fe resistance low A method for producing a lossy composite soft magnetic material.   The method for producing a high resistivity, low loss composite soft magnetic material according to claim 9 or 10, wherein the binder is an Si-O-C compound. The low melting point glass is made of Bi ₂ O ₃ —B ₂ O ₃ , SnO—P ₂ O ₅ , SiO ₂ —B ₂ O ₃ —ZnO, SiO ₂ —B ₂ O ₃ —R ₂ O (R is an alkaline earth metal) Or Li ₂ O—ZnO. 11. The method for producing a high resistivity, low loss composite soft magnetic material according to claim 9 or 10. 11. The high specific resistance and low loss composite according to claim 9, wherein the metal oxide is any one of V ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , Sb ₂ O ₃ , and MoO _2. A method for producing a soft magnetic material.   15. The Fe-based soft magnetic metal particle used is one obtained by adding at least one of Si, Al, Ni, Cr, and V to Fe. A method for producing a high resistivity and low loss composite soft magnetic material according to item 2.

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