JP2006332524A - High-strength complex soft magnetic material having high strength, high magnetic flux density, high resistance and less iron loss, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a complex soft magnetic sintered material having high strength, high magnetic flux density and high resistance, and to provide a manufacturing method thereof. <P>SOLUTION: The high-strength complex soft magnetic material having high strength, high magnetic flux density, high resistance and less iron loss is configured in such a way that an Mg-containing iron oxide film covered iron powder having a sulfur concentrated layer containing sulfur of higher concentration than that of sulfur contained in the center of iron powder in an interface region between an Mg-Fe-O three dimensional system oxide deposit film containing at least (Mg, Fe)O and the iron powder is combined in a low melting glass phase. The Mg-Fe-O three dimensional system oxide deposit film containing at least (Mg, Fe)O has a minute crystalline structure of a crystal grain size of 200 nm or low, and has the uppermost surface substantially formed of MgO. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  According to the present invention, an Mg-containing iron oxide film-coated iron powder in which an Mg-Fe-O ternary oxide deposition film containing at least (Mg, Fe) O is coated on the surface of an iron powder is made into a phase with a low melting glass. The present invention relates to a high-strength composite soft magnetic material with low iron loss having high strength, high magnetic flux density and high resistance, and a method for producing the same, and the iron loss having high strength, high magnetic flux density and high resistance is low. Composite soft magnetic materials made of high-strength composite soft magnetic materials are used as materials for various electromagnetic circuit components that require low iron loss, such as motors, actuators, yokes, cores, reactors, etc. It is.

  In general, soft magnetic materials used in various electromagnetic circuit components are required to have low iron loss. Therefore, electrical resistance is increased to reduce eddy current loss, and coercive force is reduced to reduce hysteresis loss. It is generally known. Furthermore, in recent years, since the miniaturization and high response of the electromagnetic circuit have been demanded, higher magnetic flux density is also regarded as important.

As an example of a raw material powder for producing a soft magnetic material having such a high specific resistance, an iron powder coated with an Mg-containing iron oxide film in which the surface of the iron powder is coated with an Mg-containing ferrite film by a chemical method is known ( Patent Document 1), an iron powder coated with an Mg-containing iron oxide film coated with an Mg-containing ferrite film by this chemical method is mixed with a low melting point glass powder to produce a mixed powder, and the mixed powder is compression-molded and heat treated Thus, a method for producing a dust magnetic material or the like is also known (see Patent Document 2 or 3).
Japanese Patent Laid-Open No. 11-1702 JP 2004-253787 A JP 2004-297036 A

  However, the conventional iron powder coated with Mg-containing iron oxide film coated with Mg-containing ferrite film has a high-temperature strain-relief effect on press-molded green compacts to coat the Mg-containing ferrite film on the surface of the iron powder by a chemical method. In the composite soft magnetic material obtained by firing, the Mg-containing ferrite film becomes chemically unstable and changes to deteriorate the insulation, and the adhesion of the Mg-containing ferrite film to the surface of the iron powder is not sufficient. A composite soft magnetic material produced by press-molding and heat-treating a mixed powder obtained by mixing a Mg-containing iron oxide film-coated iron powder coated with a conventional Mg-containing ferrite film with a low-melting glass powder is under press molding. In addition, the Mg-containing ferrite film is peeled off or torn, so that a sufficient insulating effect cannot be exhibited, and therefore a sufficient high specific resistance cannot be obtained.

In order to solve such problems, the present inventors firstly
(A) Mg-containing iron oxide film-coated iron powder in which an Mg-Fe-O ternary oxide deposition film containing at least Mg wustite (hereinafter referred to as (Mg, Fe) O) is coated on the surface of the iron powder ,
(B) a Mg-containing iron oxide film-coated iron powder in which an Mg-Fe-O ternary oxide deposition film containing at least (Mg, Fe) O is coated on the surface of the iron powder, In the interface region with the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O, a sulfur enriched layer containing sulfur at a higher concentration than sulfur contained in the central portion of the iron powder. Mg-containing iron oxide film-coated iron powder having,
(C) The Mg-Fe-O ternary oxide deposited film containing at least (Mg, Fe) O has a fine crystal structure with a crystal grain size of 200 nm or less. The Mg according to (a) or (b) Containing iron oxide film coated iron powder,
(D) The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O has the outermost surface substantially composed of MgO, (a), (b) or ( c) The Mg-containing iron oxide film-coated iron powder described in the above was invented.

The Mg-containing iron oxide film-coated iron powder described in (a), (b), (c) or (d) previously invented is subjected to oxidation treatment by heating the iron powder in an oxidizing atmosphere in advance. As a result, an iron powder having an iron oxide film formed on the surface of the iron powder (hereinafter referred to as “oxidized iron powder”) was prepared, and the mixed powder obtained by adding and mixing Mg powder into this oxidized iron powder was inert. After being heated in a gas atmosphere or vacuum atmosphere, etc., it is obtained by performing an oxidation treatment in which it is further heated in an oxidizing atmosphere, and the Mg-containing iron oxide film-coated iron powder previously invented is
(A) Various oxides of Mg-Fe-O ternary system such as (Mg, Fe) O, (Mg, Fe) ₃ O _{4 and the} like represented by the generally known MgO-FeO-Fe ₂ O ₃ system Among them, a Mg—Fe—O ternary oxide deposition film containing at least (Mg, Fe) O is formed on the surface of the iron powder, and this Mg—Fe—O ternary containing at least (Mg, Fe) O. Mg-containing iron oxide film-coated iron powder coated with an oxide-based oxide film on the surface of iron powder is more Mg than iron powder coated with Mg-containing iron oxide film in which an Mg-containing ferrite film is formed on the surface of conventional iron powder. Since the adhesion of the iron oxide film to the iron powder is remarkably superior, the iron oxide film, which is an insulating film, is less likely to break during press molding and the iron powder does not come into contact with each other. Even if it goes, the insulating property of the Mg-containing iron oxide film decreases The eddy current loss is low because it can maintain a very high resistance, and the hysteresis loss can be kept low because the coercive force can be further reduced when the strain relief firing is performed. A composite soft magnetic material having
(B) In the interface region between the iron powder and the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O, sulfur contained as an inevitable impurity in the center of the iron powder A sulfur-enriched layer containing a high concentration of sulfur is formed,
(C) The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O formed on the surface of the iron powder has a fine crystal structure with a crystal grain size of 200 nm or less;
(D) The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O formed on the surface of the iron powder is preferably as the amount of MgO contained in the outermost surface is larger. The outermost surface is made based on the knowledge that it is most preferable that the outermost surface is substantially composed of MgO.

The production method of the Mg-containing iron oxide film-coated iron powders (a) to (c) previously invented will be described more specifically. First, the iron powder is preliminarily set in an oxidizing atmosphere at a temperature of 50 to 500 ° C. Oxidation-treated iron powder in which an iron oxide film is formed on the surface of the iron powder by heating and oxidation treatment is produced, and the mixed powder obtained by adding and mixing Mg powder to these powders is temperature: 150 to 1100 C., pressure: 1 × 10 ⁻¹² to 1 × 10 ⁻¹ MPa in an inert gas atmosphere or vacuum atmosphere, and if necessary, further heated in an oxidizing atmosphere at a temperature of 50 ° C. to 350 ° C. and then oxidized. It is produced by applying.

In addition, the Mg—Fe— in which the outermost surface of the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O described in the above (d) is substantially composed of MgO. O ternary oxide deposited film is prepared by oxidizing iron powder by heating it in an oxidizing atmosphere at a temperature of 50-500 ° C in advance to form an iron oxide film on the surface of the iron powder. Then, the mixed powder obtained by adding and mixing more Mg powder to these powders is an inert gas atmosphere or vacuum at a temperature of 150 to 1100 ° C. and a pressure of 1 × 10 ⁻¹² to 1 × 10 ⁻¹ MPa. After heating in an atmosphere, it is obtained by further heating in an oxidizing atmosphere for a longer time and then performing an oxidation treatment.

The Mg-containing iron oxide film-coated iron powders (a) to (d) previously invented will be described in more detail. The Mg-Fe-O ternary oxide deposited film formed on the surface of the Mg-containing iron oxide film-coated iron powders (a) to (d) is generally known as Mg wustite ((Mg, Fe ) O) and Mg-Fe-O-based oxides such as (Mg, Fe) ₃ O ₄ are preferable to contain Mg wustite (Mg, Fe) O oxide, so at least (Mg, Fe) O. An Mg—Fe—O ternary oxide deposited film containing is preferable, and the outermost surface of the deposited film containing at least (Mg, Fe) O is most preferably composed of MgO. This Mg wustite is not limited to (Mg, Fe): O = 1: 1, but O may have a solid solution width.
The term “deposited film” usually refers to a film in which atoms constituting the film formed by vacuum evaporation or sputtering are deposited on a substrate, for example, and includes at least (Mg, Fe) O formed on the surface of the iron powder. The Mg—Fe—O ternary oxide deposition film indicates a film in which iron oxide (Fe—O) and Mg on the iron powder surface having an iron oxide film are deposited on the iron powder surface with a reaction. The film thickness of the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O formed on the surface of the iron powder is equal to the high magnetic flux density of the compacted composite soft magnetic material. In order to obtain a high specific resistance, it is preferably in the range of 5 nm to 500 nm. If the film thickness is less than 5 nm, the specific resistance of the powder-molded composite soft magnetic material is not sufficient and the eddy current loss increases. On the other hand, if the film thickness is thicker than 500 nm, it is not preferable. This is because the magnetic flux density is lowered, which is not preferable. A more preferable film thickness is in the range of 5 nm to 200 nm.

The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O formed on the surface of the iron powder coated with the Mg-containing iron oxide film of the above-described inventions (a) to (d), , Sulfur containing a higher concentration of sulfur than the sulfur contained in the center of the iron powder in the interface region between the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O and the iron powder Has a thickened layer. Having this sulfur-concentrated layer can be confirmed from the fact that the sulfur concentration is measured by Auger electron spectroscopy, and this is shown in a graph, indicating a sulfur concentration peak. By having such a sulfur-concentrated layer in the interface region, the adhesion of the Mg-Fe-O ternary oxide deposited film containing at least (Mg, Fe) O to the iron powder surface becomes even better. The deposited film can follow the deformation of the powder at the time of compacting to prevent the coating from being torn, the contact bonding between the iron powders can be prevented even during firing, and high resistance can be maintained, Therefore, eddy current loss is reduced. The sulfur in the sulfur-concentrated layer is considered to be supplied from sulfur contained in the surface portion of the iron powder because the iron powder contains sulfur as an unavoidable impurity.
The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O formed on the surface of the Mg-containing iron oxide film-coated iron powders (a) to (d) has crystal grains. Is preferably as fine as possible, and preferably has a fine crystal structure with a crystal grain size of 200 nm or less. By having such a fine crystal structure, the microcrystalline Mg—Fe—O ternary oxide deposited film can follow the deformation of the powder during compacting and prevent the coating from being broken. In addition, contact bonding between iron powders can be prevented, and even when high-temperature strain relief firing is performed, the oxide is stable and insulation deterioration can be prevented, and eddy current loss is reduced with high resistance. If the crystal grain size is larger than 200 nm, the coating will be broken during compression molding, resulting in reduced insulation, and the Mg—Fe—O ternary oxide deposited film will be thicker than 500 nm. This is not preferable because the magnetic flux density of the composite soft magnetic material is lowered.
In addition, the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O formed on the surface of the Mg-containing iron oxide film-coated iron powder (d) is MgO on the outermost surface. The content of is preferably as high as possible, and is most preferably substantially composed of MgO. When the outermost surface is substantially MgO, the diffusion of Fe is prevented even during firing of the green compact that has been press-molded, and contact bonding between iron powders can be prevented. This is because loss is reduced.

This invention is a high-strength composite soft magnetic material having higher strength, higher magnetic flux density and higher specific resistance using the Mg-containing iron oxide film-coated iron powder described in (a) to (d) above, and its An object of the present invention is to provide a production method, which is a high-strength, high-magnetic flux formed by bonding the Mg-containing iron oxide film-coated iron powder described in (a) to (d) above in a glass phase. The present invention relates to a high-strength composite soft magnetic material having low density and high resistance, and a method for producing the same. That is, this invention
(1) An Mg-containing iron oxide film-coated iron powder in which an Mg-Fe-O ternary oxide deposited film containing at least (Mg, Fe) O is coated on the surface of the iron powder is bonded with a low melting glass phase. High strength composite soft magnetic material with low iron loss and high strength, high magnetic flux density and high resistance,
(2) A Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O is coated on the surface of the iron powder, and the Mg—Fe—O containing at least (Mg, Fe) O. The Mg-containing iron oxide film-coated iron powder having a sulfur-concentrated layer containing a higher concentration of sulfur than the sulfur contained in the center of the iron powder in the interface region between the ternary oxide deposited film and the iron powder has a low melting point. High strength composite soft magnetic material with low iron loss having high strength, high magnetic flux density and high resistance bonded by glass phase,
(3) The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O has a fine crystal structure with a crystal grain size of 200 nm or less. High strength composite soft magnetic material with low iron loss with strength, high magnetic flux density and high resistance,
(4) The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O has the outermost surface substantially composed of MgO (1), (2) or ( 3) A high-strength composite soft magnetic material having a low iron loss and having a high strength, a high magnetic flux density and a high resistance as described above,
(5) A low melting point glass powder is mixed with the Mg-containing iron oxide film-coated iron powder described in (1), (2), (3) or (4) to produce a mixed powder, and the mixed powder is compression molded. It is characterized by a method for producing a high-strength composite soft magnetic material having a high iron strength, high magnetic flux density, and high resistance and low iron loss.

The low-melting-point glass powder is a hard powder at room temperature even though the melting point is low, and the low-melting-point glass powder is added to the Mg-containing iron oxide film-coated iron powder described in (1), (2), (3) or (4). There is a possibility that the Mg-containing iron oxide film formed on the surface of the Mg-containing iron oxide film-coated iron powder may be damaged or damaged when the mixed powder produced by mixing is compression molded.
In order to avoid this, the complex or alkoxide of the element constituting the low melting point glass is used as the organic solvent on the surface of the Mg-containing iron oxide film-coated iron powder described in (1), (2), (3) or (4). The low melting point in the Mg-containing iron oxide film-coated iron powder coated with the low-melting glass precursor was prepared by applying the melted solution and drying to prepare the Mg-containing iron oxide film-coated iron powder coated with the low-melting-point glass precursor. An Mg-containing iron oxide film-coated iron powder was prepared by thermally decomposing the organic components of the glass precursor to coat the low-melting glass with the low-melting glass coated on the surface of the Mg-containing iron oxide film-coated iron powder. After compression-molding the Mg-containing iron oxide film-coated iron powder coated with glass, heat treatment is performed at a temperature of 300 to 1000 ° C., or the Mg-containing oxidation described in the above (1), (2), (3) or (4) An iron powder coated with Mg-containing iron oxide film coated with a low-melting-point glass precursor by applying a solution obtained by dissolving a complex or alkoxide of an element constituting the low-melting-point glass in an organic solvent on the surface of the film-coated iron powder and drying it. After producing and compression-molding the Mg-containing iron oxide film-coated iron powder coated with this low-melting glass precursor, heat treatment is performed at a temperature of 300 to 1000 ° C., and the organic component of the low-melting glass precursor is heated during the heat treatment. It is more preferable to prepare by decomposing. Therefore, the present invention
(6) A complex or alkoxide of an element constituting the low-melting glass was dissolved in an organic solvent on the surface of the Mg-containing iron oxide film-coated iron powder described in (1), (2), (3) or (4). An Mg-containing iron oxide film-coated iron powder coated with a low-melting glass precursor was prepared by applying the solution and drying, and the low-melting-point glass precursor in the Mg-containing iron oxide film-coated iron powder coated with this low-melting glass precursor The organic component of the body is thermally decomposed to produce a Mg-containing iron oxide film-coated iron powder coated with a low-melting glass coated with a low-melting glass on the surface of the Mg-containing iron oxide film-coated iron powder. A method for producing a high-strength composite soft magnetic material with low iron loss, having high strength, high magnetic flux density and high resistance, which is compression-molded and coated with Mg-containing iron oxide film-coated iron powder,
(7) On the surface of the Mg-containing iron oxide film-coated iron powder described in (1), (2), (3) or (4), an element complex or alkoxide constituting the low-melting glass is dissolved in an organic solvent. After the solution is applied and dried, an iron powder coated with Mg-containing iron oxide film coated with a low-melting glass precursor is prepared, and the iron powder coated with Mg-containing iron oxide film coated with the low-melting glass precursor is compression-molded. A method for producing a high-strength composite soft magnetic material having low iron loss and having high strength, high magnetic flux density and high resistance by heat-treating and thermally decomposing an organic component of the low-melting-point glass precursor during the heat treatment,
(8) The temperature of the heat treatment is in the range of 300 to 1000 ° C. The high strength composite softening having high strength, high magnetic flux density and high resistance and low iron loss as described in (5), (6) or (7). It is characterized by a method for manufacturing a magnetic material.

In the composite soft magnetic sintered material having a high strength, a high magnetic flux density and a high resistance and a small iron loss according to the present invention, and a method for producing the same, the Mg-containing iron oxide film coating according to the above (a) to (d) described above The low melting point glass formed on the surface of the iron powder is SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ glass, SiO ₂ —BaO—Al ₂ O ₃ glass, SiO ₂ —BaO—B ₂ O ₃ glass. , SiO ₂ —BaO—Li ₂ O ₃ glass, SiO ₂ —B ₂ O ₃ —CaO glass, SiO ₂ —MgO—Al ₂ O ₃ glass, B ₂ O ₃ —Li ₂ O ₃ glass, PbO —B ₂ O ₃ glass, PbO—B ₂ O ₃ —ZnO glass, Bi ₂ O ₃ —B ₂ O ₃ glass, Li ₂ O—ZnO glass, SiO ₂ —B ₂ O ₃ —PbO glass _{, Al 2 O 3 -B 2 O} 3 -PbO based glass, SnO-P ₂ O ₅ based glass, Z O-P ₂ O ₅ based glass, phosphoric acid-based glass such as CuO-P ₂ O ₅ based glass, low-melting glass All of these low-melting glass having a softening temperature has a low softening temperature of 300 to 800 ° C. It is.

The complex of the elements constituting the low melting glass, which is a low melting glass precursor for forming these low melting glasses, includes hydride complexes, carbonyl complexes, metallocene complexes, alkyl complexes, silyl complexes, porphyrin complexes, allyl complexes, aromatics. Ring complexes, olefin complexes, diene complexes, carbene complexes, carbene complexes, arene complexes, phosphine complexes, alkyne complexes, diketone complexes (diketonate compounds) can be used, and alkoxides of elements that constitute low-melting glass , Methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, sec-butoxy group, t-butoxy group, amyloxy group, phenoxy group, naphthoxy group, etc. Use an alkoxide having a species or two or more species as functional groups Door can be.
Other organic metals such as metal salts of organic acids such as carboxylic acids can also be used, but when the organic component decomposes, the decomposition product carbon tends to remain on the powder surface, and the dust core This is not preferable because it reduces the mechanical strength.

  In the method for producing a composite soft magnetic sintered material having high strength, high magnetic flux density and high resistance according to the present invention, the surface of the iron powder coated with Mg-containing iron oxide film described in the above (a) to (d) is invented. The temperature for sintering the low melting point glass precursor or the powder coated with the low melting point glass is preferably in the range of 300 to 1000 ° C. (more preferably 400 to 800 ° C.). The reason is that if the sintering temperature is less than 300 ° C., the glass precursor or glass does not melt, and therefore, the composite soft magnetic sintered material obtained is insufficient in strength because it is not sufficiently bonded to the glass. On the other hand, if the sintering is performed at a temperature exceeding 1000 ° C., the specific resistance is lowered, which is not preferable. The sintering atmosphere at this time may be any of air, hydrogen, inert gas, nitrogen gas, carbon dioxide gas or vacuum, but an inert gas or nitrogen gas atmosphere is most preferable.

  According to the present invention, the addition of a small amount of low-melting glass can provide a composite soft magnetic sintered material having high strength and high resistance, and having a high magnetic flux density, and has excellent effects in the electrical and electronic industries. Is.

A pure iron powder having an average particle size of 70 μm and containing an extremely small amount of sulfur as an inevitable impurity was prepared as a raw material powder, and an Mg powder having an average particle size of 50 μm was prepared.
First, an oxidized iron powder having an iron oxide film on its surface is produced by oxidizing the pure iron powder in the atmosphere at a temperature of 220 ° C. for 2 hours. The prepared Mg powder was added and mixed in a ratio of oxidized iron powder: Mg powder = 99.7% by mass: 0.3% by mass to prepare a mixed powder. The obtained mixed powder was heated at 650 ° C. Pressure: 2.7 × 10 ⁻⁴ MPa After holding for 1 hour, further in the atmosphere, temperature: 200 ° C., and holding for 1 hour, the Mg-containing iron oxide film coated with the deposited film on the surface of the iron powder Iron powder was produced. The deposited film formed on the Mg-containing iron oxide film-coated iron powder was analyzed by an X-ray photoelectron spectrometer and the binding energy was analyzed. As a result, Mg—Fe—O containing at least (Mg, Fe) O was found. It was found to be a ternary oxide deposited film. As a result of investigating the interface region between the iron powder and the Mg—Fe—O ternary oxide deposited film in this Mg-containing iron oxide film-coated iron powder by a method using an Auger electron spectrometer, at least (Mg, Fe) O In the interface region between the Mg-Fe-O ternary oxide deposited film containing iron and the iron powder, and more clearly in the Auger electron spectroscopy than the impurity sulfur (background) contained in the center of the iron powder From the fact that sulfur was detected, it was found that a sulfur concentrated layer containing a higher concentration of sulfur than the sulfur contained in the central part of the iron powder was found. Furthermore, as a result of observing the structure of the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O in the Mg-containing iron oxide film coated iron powder with an electron microscope, the average of the deposited film It was found that the thickness was 60 nm and the maximum crystal grain size was 40 nm.
Furthermore, a low melting point glass powder having an average particle size of 1.4 μm and a composition of SiO ₂ : 80% by mass and B ₂ O ₃ : 20% by mass is prepared, and further as a complex or alkoxide of the elements constituting the low melting point glass Silicon tetraethoxide (tetraethoxysilane) as a SiO ₂ raw material, triphenyl phosphate as a P ₂ O ₅ raw material, tin acetylacetonate as a SnO raw material, tri-i-propoxybismuth as a Bi ₂ O ₃ raw material, Metal alkoxides and metal complexes such as di-n-butoxy zinc as a ZnO raw material and barium dipivaloylmethanate as a BaO raw material were prepared. Furthermore, hexane was prepared as an organic solvent for dissolving these metal alkoxides and metal complexes.

Example 1
A metal alkoxide and a metal complex are dissolved in an organic solvent so as to have a low-melting glass composition shown in Table 1 in terms of oxides, and a solution is prepared. The coated iron powder (hereinafter referred to as precursor) coated with a low-melting-point glass precursor on the surface of the Mg-containing iron oxide film-coated iron powder by adding and immersing in the ratio shown in Table 1 and drying while stirring. A1 to A4 (referred to as body-coated powder) were prepared.

These precursor-coated iron powders A1 to A4 shown in Table 1 are filled in dies each having a lubricant applied to the inner wall, and are molded at a molding pressure of 980 MPa, so that the outer diameter is 35 mm, the inner diameter is 25 mm, and the thickness is: A ring-shaped molded body having dimensions of 5 mm and a bar-shaped molded body having dimensions of length: 60 mm, width: 10 mm, and thickness: 5 mm were prepared, and these ring-shaped molded body and bar-shaped molded body were placed in a nitrogen atmosphere. Temperature: 600 ° C. A ring test piece and a bar-shaped test piece made of the composite soft magnetic materials 1 to 4 of the present invention were produced by heat treatment for 1 hour.
After measuring the underwater density of the ring-shaped test piece comprising the composite soft magnetic materials 1 to 4 of the present invention, winding was performed, and the maximum relative magnetic permeability, excitation magnetic flux density, 1.5 T, frequency 50 Hz and 1 were measured using a BH analyzer. The iron losses W _{1.5 / 50} and W _{1.0 / 400} at 0.0T and a frequency of 400 Hz were measured and shown in Table 2.
Further, specific resistance was measured for the bar-shaped test piece by the four probe method, and bending strength was measured by three-point bending with a span of 45 mm. The results are shown in Table 2.

Example 2
Precursor-coated iron powders A1 to A4 obtained by coating the surface of the Mg-containing iron oxide film-coated iron powder with the low melting point glass precursor shown in Table 1 prepared in Example 1 in an air atmosphere at a temperature of 550 ° C. for 1 hour. By holding, coated iron powders (hereinafter referred to as low melting point glass-coated powders) a1 to a4 in which the surface of the Mg-containing iron oxide film-coated iron powder was coated with a low melting point glass were produced.
These low melting point glass-coated iron powders a1 to a4 are filled in dies each having an inner wall coated with a lubricant, and are molded at a molding pressure of 980 MPa, so that the outer diameter is 35 mm, the inner diameter is 25 mm, and the thickness is 5 mm. A ring-shaped molded body having a length of 60 mm, a width of 10 mm, and a thickness of 5 mm was prepared, and the ring-shaped molded body and the bar-shaped molded body were heated in a nitrogen atmosphere at a temperature of 600 ° C. A ring test piece and a bar-shaped test piece made of the composite soft magnetic materials 5 to 8 of the present invention were prepared by performing heat treatment for 1 hour. After measuring the underwater density of the obtained ring-shaped test piece, it was wound, and the iron loss at a maximum relative magnetic permeability, excitation magnetic flux density, 1.5 T, frequencies 50 Hz and 1.0 T, and frequency 400 Hz was measured with a BH analyzer. W _{1.5 / 50} and W _{1.0 / 400} were measured and shown in Table 2.
Further, specific resistance was measured for the bar-shaped test piece by the four probe method, and bending strength was measured by three-point bending with a span of 45 mm. The results are shown in Table 2.

Example 3
To the Mg-containing iron oxide film-coated iron powder prepared in advance, a glass powder having an average particle diameter of 1.4 μm and a composition of SiO ₂ : 80% by mass and B ₂ O ₃ : 20% by mass was prepared. Containing iron oxide film coated iron powder: Glass powder = 99.3 wt%: Blended to a ratio of 0.7 wt% to produce a mixed powder, and put the obtained mixed powder into a mold A bar-shaped green compact having dimensions of 60 mm in length, 10 mm in width, and 5 mm in thickness, and a ring-shaped green compact having dimensions of 35 mm in outer diameter, 25 mm in inner diameter, and 5 mm in height. The green compact thus obtained was sintered in a nitrogen atmosphere at a temperature of 600 ° C. and held for 30 minutes to prepare a ring test piece and a bar-shaped test piece made of the composite soft magnetic material 9 of the present invention. . After measuring the underwater density of the obtained ring-shaped test piece, it was wound, and the iron loss at a maximum relative magnetic permeability, excitation magnetic flux density, 1.5 T, frequencies 50 Hz and 1.0 T, and frequency 400 Hz was measured with a BH analyzer. W _{1.5 / 50} and W _{1.0 / 400} were measured and shown in Table 2.
Further, specific resistance was measured for the bar-shaped test piece by the four probe method, and bending strength was measured by three-point bending with a span of 45 mm. The results are shown in Table 2.

Conventional Example 1
A conventional Mg-containing iron oxide film-coated iron powder in which a Mg-containing ferrite layer is formed on the surface of pure iron powder by a chemical method is prepared, and the average particle diameter prepared in advance for this conventional Mg-containing iron oxide film-coated iron powder is 1 A glass powder having a composition of SiO ₂ : 80% by mass and B ₂ O ₃ : 20% by mass at 4 μm was used. Mg-containing iron oxide film-coated iron powder: glass powder = 99.3% by mass: 0.7% by mass It mixes so that it may become a ratio, mixes and produces mixed powder, puts the obtained mixed powder into a metal mold, press-molds it, and it is bar shape which has a size of length: 60mm, width: 10mm, thickness: 5mm A green compact and a ring-shaped green compact having an outer diameter of 35 mm, an inner diameter of 25 mm, and a height of 5 mm were molded, and the obtained green compact was maintained at a temperature of 600 ° C. for 30 minutes in a nitrogen atmosphere. Sintering is performed under the conditions, and a conventional ring test made of composite soft magnetic material is performed. To prepare a piece and the bar-shaped test piece.
After measuring the underwater density of the obtained ring-shaped test piece, it was wound, and the iron loss at a maximum relative magnetic permeability, excitation magnetic flux density, 1.5 T, frequencies 50 Hz and 1.0 T, and frequency 400 Hz was measured with a BH analyzer. W _{1.5 / 50} and W _{1.0 / 400} were measured and shown in Table 2.
Further, specific resistance was measured for the bar-shaped test piece by the four probe method, and bending strength was measured by three-point bending with a span of 45 mm. The results are shown in Table 2.

From the results shown in Tables 1 and 2, the test pieces prepared with the composite soft magnetic materials 1 to 9 of the present invention were compared with the test pieces prepared with the conventional composite soft magnetic materials shown in Table 2 in terms of DC magnetic characteristics, AC magnetic characteristics, Since all the mechanical strengths show excellent values, it can be seen that the composite soft magnetic sintered materials 1 to 9 of the present invention show superior characteristics as compared with conventional composite soft magnetic materials.
In particular, when the composite soft magnetic material 9 of the present invention is compared with the conventional composite soft magnetic material, the test piece prepared with the composite soft magnetic material 9 of the present invention is prepared using low melting point glass powder in the same manner as the conventional composite soft magnetic material. Even so, the Mg-containing iron oxide film-coated iron powder coated with the Mg-Fe-O ternary oxide deposited film containing at least (Mg, Fe) O, invented earlier, has excellent adhesion to iron powder. Therefore, it can be seen that the iron loss is extremely small as compared with the iron powder coated with Mg-containing iron oxide film formed by a conventional chemical method.

Claims (8)

An Mg-Fe-O ternary oxide deposited film containing at least (Mg, Fe) O is bonded to the iron powder coated with Mg-containing iron oxide film coated on the surface of the iron powder with a low melting glass phase. A high-strength composite soft magnetic material with low iron loss and having high strength, high magnetic flux density and high resistance. A Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O is coated on the surface of the iron powder, and the Mg—Fe—O ternary system containing at least (Mg, Fe) O. The Mg-containing iron oxide film-coated iron powder having a sulfur-concentrated layer containing a higher concentration of sulfur than the sulfur contained in the center of the iron powder in the interface region between the oxide deposited film and the iron powder is a low melting glass phase. A high-strength composite soft magnetic material having low iron loss and having high strength, high magnetic flux density, and high resistance. 3. The high strength according to claim 1, wherein the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O has a fine crystal structure with a crystal grain size of 200 nm or less. High strength composite soft magnetic material with low magnetic loss and high magnetic flux density and high resistance. 4. The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O has an outermost surface substantially composed of MgO. High strength composite soft magnetic material with low iron loss and high strength, high magnetic flux density and high resistance. A mixed powder is prepared by mixing a low melting point glass powder with the Mg-containing iron oxide film-coated iron powder according to claim 1, 2, 3 or 4, and the mixed powder is compression-molded and then heat-treated. A method for producing a high-strength composite soft magnetic material having high strength, high magnetic flux density and high resistance and low iron loss. A low melting point by applying and drying a solution of an element complex constituting a low melting point glass or an alkoxide in an organic solvent on the surface of the Mg-containing iron oxide film-coated iron powder according to claim 1, 2, 3 or 4 By producing an iron powder coated with Mg-containing iron oxide film coated with a glass precursor and thermally decomposing the organic components of the low-melting glass precursor in the iron powder coated with Mg-containing iron oxide film coated with this low-melting glass precursor Low melting point glass-Mg containing iron oxide film coated iron powder coated with low melting point glass on the surface of Mg containing iron oxide film coated iron powder was produced, and this low melting point glass-Mg containing iron oxide film coated iron powder was compression molded. A method for producing a high-strength composite soft magnetic material having low iron loss and having high strength, high magnetic flux density and high resistance, characterized by heat treatment. A low melting point by applying a solution of an element complex or alkoxide constituting the low melting point glass in an organic solvent on the surface of the iron powder coated with Mg-containing iron oxide film according to claim 1, 2, 3 or 4 and drying. An iron powder coated with Mg-containing iron oxide film coated with a glass precursor was prepared, heat-treated after compression-molding the iron powder coated with Mg-containing iron oxide film coated with this low-melting glass precursor, A method for producing a high-strength composite soft magnetic material having low iron loss and having high strength, high magnetic flux density and high resistance, characterized by thermally decomposing an organic component of a glass precursor. 8. The high-strength composite soft magnetic material with low iron loss having high strength, high magnetic flux density and high resistance according to claim 5, 6 or 7, wherein the temperature of the heat treatment is in the range of 300 to 1000 ° C. Production method.