JPH11238614A - Soft magnetic material and manufacture thereof and electrical equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a soft magnetic material having high permeability, superior frequency characteristics, even superior mechanical strength and high saturation magnetic flux density. SOLUTION: In the manufacture of the soft magnetic material, a molded form 4 is molded of magnetic powder 1, consisting of the metallic particles 2 of iron or an iron alloy having initial oxide films 31 on surfaces and having mean grain size of 10-400 μm, the void sections of the molded form are impregnated with at least one kind from among of a binding metal 6 of molten aluminum, magnesium and these alloys as an element easier to be oxidized than iron, and the oxide of iron is reduced, thus obtaining the soft magnetic material with the final oxide films 32 of the binding metal. Heat treatment is conducted at a temperature of 300 deg.C or higher after the impregnation of the binding metal, and the final oxide films 32 may also be formed. Accordingly, a stator or a rotor for a motor, a transformer, a reactor, a thyristor valve, a magnetic head, etc., can be manufactured by the use of the prepared soft magnetic material as an iron core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic material having high strength, low eddy current loss, high saturation magnetic flux density and high magnetic permeability at high frequencies, a method of manufacturing the same, a rotor and a stator of a motor using the same, The present invention relates to electrical equipment such as a reactor, a transformer, and a yoke for a magnetic head.

[0002]

2. Description of the Related Art In recent years, electric devices such as motors have been frequently used in a high frequency range. As a magnetic material used for such a device, a soft magnetic material having excellent magnetic properties is selected and used. However, in AC use, iron loss (sum of hysteresis loss and eddy current loss) is large, resulting in energy loss. Eddy current loss increases in proportion to the square of the frequency, so in order to reduce AC loss,
For example, a silicon steel sheet is laminated and used. Nevertheless, eddy current loss accounts for 20% of iron loss in the commercial frequency range. Also, 1
When the frequency exceeds kHz, the eddy current loss becomes larger than the hysteresis loss, and the hysteresis loss also becomes larger. Therefore, a magnetic material used in a high-frequency region can be used only at a magnetic flux density much lower than the saturation magnetic flux density of the original material due to a decrease in magnetic permeability. Energy conservation is also being called out from global environmental issues, and it is essential to improve the efficiency of motors.

[0003]

In order to solve such a problem, application of an amorphous material to a soft magnetic material has been studied. However, although there is an effect of reducing eddy current loss, the magnetic material can be applied with a small stress during molding of a product. The use is very limited due to the reduced properties. A dust core formed by compression molding iron covered with an oxide film (for example, Japanese Patent Publication No. 6-8257)
No. 7) and a resin molded product in which a resin is coated on the surface of an iron powder (for example, Japanese Patent Application Laid-Open No. 9-102409). Dust cores have weak binders in the powder, which limits the application of the molded product to chipping or cracking during handling, and improves magnetic properties as long as the electrical resistance does not decrease. Magnetic properties were also insufficient because high-temperature heat treatment could not be performed for a long time. Since the resin molded body uses resin as a binder, heat treatment for improving the magnetic properties of iron deteriorated by stress at the time of molding cannot be performed at 700 ° C. or more, so only electric resistance is large, Properties were very low. If the heat treatment is performed at 700 ° C. or more, the resin film disappears and the electric resistance decreases. Therefore, an object of the present invention is to provide a soft magnetic material having a high magnetic flux density and a high saturation magnetic flux density having an excellent mechanical strength and an excellent frequency characteristic, a method of manufacturing the same, and an electric device using the same. And

[0004]

Means for Solving the Problems To solve the above problems, the present invention has the following constitution. (1) a magnetic powder composed of metal particles made of iron or an iron alloy having an average particle diameter of 10 to 400 μm and a metal oxide covering the periphery of the metal particles and mainly containing an element more easily oxidized than iron, and the magnetic powder A soft magnetic material which binds together and has a bonding metal containing the component of the metal oxide. Since the oxide is composed of a metal that is easier to oxidize than iron,
Iron oxide can be reduced to form a new oxide and at the same time be used as a binder. (2) The thickness of the metal oxide is 0.02 to 10 μm, and the volume of the magnetic powder is 80% or more of the whole. By limiting the thickness of the oxide to the range of 0.02 to 10 μm, the insulating property is maintained, and the specific resistance is increased to 100 μΩcm or more. When the specific resistance is 100 μΩcm or more, the specific resistance is five times as large as that of the silicon steel sheet.
Can be reduced by a factor of one. Further, since there is little nonmagnetic phase in the entire material, the saturation magnetic flux density does not decrease. Further, since the volume of the magnetic powder is set to 80% or more, the portion of the magnetic material does not decrease, and the saturation magnetic flux density becomes 15000 G or more, which is equivalent to the value of magnetic steel currently used. (3) The metal particles contain at least one of silicon and aluminum, and have a volume of 8% or less. (4) The metal particles are Sendust or an Fe-Co alloy. (5) The metal oxide is any of aluminum oxide, silicon oxide, and magnesium oxide. (6) The soft magnetic material according to any one of claims 1 to 5, wherein a part of the metal oxide is an iron oxide. (7) The binding metal is aluminum, magnesium, or an alloy thereof. Since these elements have a higher oxide generation energy than iron, they reduce the oxide of iron, and a new metal oxide film having high insulation resistance can be obtained. (8) The binding metal is an aluminum alloy containing 40 to 70% by volume of silicon. By limiting silicon to 40-70%, the coefficient of thermal expansion becomes the same as that of iron particles. For this reason, since no stress is applied to the iron particles during the heat treatment, the deterioration of the magnetic properties is very small. (9) Average particle size having metal oxide on the surface 10 to 400μ
m is formed of a magnetic powder made of metal particles of iron or an iron alloy, and at least one of molten aluminum, magnesium, and their alloys as bonding metals in the voids of the molded body while the molded body is heated. This is a production method in which one type is impregnated to obtain a soft magnetic material. By pressurizing and impregnating, for example, aluminum, which has been melted into a molded body of iron particles whose surface has been oxidized, iron oxide is reduced and changed to aluminum oxide. That is, a material in which aluminum as a binder is present between iron particles covered with aluminum oxide and particles is formed. The boundary between aluminum as the binder and aluminum oxide is made of a graded alloy. That is, the bonding force is increased by gradually changing from metallic aluminum to aluminum oxide in the direction of the iron particles. Furthermore, this structure does not change the characteristics of aluminum oxide even when heated at 700 ° C. or higher to remove the stress remaining on the iron particles during molding. (10) A compact is formed from magnetic powder composed of iron or iron alloy metal particles having an average particle size of 10 to 400 μm,
The surface of the metal particles is oxidized by heating to at least 00 ° C. to form a metal oxide, and in a state where the molded body is heated, molten aluminum, magnesium, and the like, which are bonding metals in voids of the molded body, This is a method for producing a soft magnetic material by impregnating at least one kind of alloy. (11) A method for producing a soft magnetic material in which after the impregnation with the binding metal, heat treatment is performed at 700 ° C. or higher to remove the residual stress of the metal particles. By performing the heat treatment at 700 ° C. or more, the residual stress of iron can be removed, so that the magnetic properties can be significantly improved. Further, the formation of a new oxide film can be promoted simultaneously with the reduction of the iron oxide. (12) After impregnating the binding metal, a heat treatment is performed to maintain a constant temperature between the melting point of the binding metal and 300 ° C. to remove the metal oxide of iron formed on the surface of the metal particles by the binding metal. And forming the metal oxide around the metal particles by a soft magnetic material. 300
When aluminum and iron oxide are brought into contact at a temperature of not less than ° C, iron oxide is reduced to form aluminum oxide. Although a lower temperature may be used, it takes time, which is disadvantageous in terms of cost. Iron oxide refers to Fe ₂ O ₃ , Fe ₃ O ₄ , FeO, and composite substances thereof. In order to reduce iron oxides, iron oxides may remain depending on the reducing conditions, and there is no problem as long as the characteristics are not affected. (13) A method for producing a soft magnetic material, wherein the inside of the compact is depressurized when the magnetic powder is impregnated with the binding metal. By reducing the pressure inside the molded body, the molten metal easily enters between the particles. In addition, as for the heating during the impregnation, the higher the temperature, the more easily the molten metal enters between the particles. (14) a magnetic powder composed of metal particles made of iron or an iron alloy having an average particle diameter of 10 to 400 μm and a metal oxide covering the periphery of the metal particles and mainly containing an element more easily oxidized than iron, and the magnetic powder A stator or a rotor of an electric motor in which a core is formed using a soft magnetic material having a bonding metal containing the components of the metal oxide, and
Transformers, reactors, thyristor valves, and magnetic heads.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view showing the concept of the manufacturing process for manufacturing the soft magnetic material of the present invention. In the figure, 1 is a magnetic powder, 2 is a metal particle, 3 is a metal oxide covering the surface of the metal particle 2, 4 is a molded product obtained by molding the magnetic powder 1 into a desired shape, and 5 is a gap between the magnetic powders 1. , 6 are voids 5
Is a bonding metal that is impregnated with the magnetic powder to bond one magnetic powder to another. Reference numeral 7 denotes a container for impregnating the compact 4 and the bonding metal 6 under pressure, and 8 denotes a piston. There are two types of metal oxides 3,
One is an initial oxide film 31 that may be formed from the oxide film of the metal particles 2 from the beginning and the other may be generated by an oxidation treatment. The final oxide film 32 which is formed and finally becomes an insulating film
It is. The magnetic powder 1 was prepared by forming Fe ₂ O _{3 on} the surface of iron metal particles 2 as the initial oxide film 31, and aluminum was used as the bonding metal 6. The molded body 4 is press-formed into a rectangular parallelepiped having a length of 5 mm, a width of 10 mm, and a length of 60 mm. Next, as shown in Table 1, samples were prepared by changing the composition of the magnetic powder 1 variously.

[0006]

[Table 1]

The shape of the molded body 4 is 30 m in outer diameter shown in FIG.
m, an inner diameter of 20 mm, and a height of 5 mm were used, and a rectangular parallelepiped having a length of 5 mm, a width of 10 mm, and a length of 60 mm shown in FIG. 1 was used. The ring-shaped sample was used for performing magnetic measurement to measure the magnetic permeability and the saturation magnetic flux density, and the rectangular parallelepiped sample was used for performing a resistance value and an impact test. The molding pressure was 7 ton / cm ² . For the sample of No. 16, the initial oxide film 31 was not attached to the surface of the particles. Therefore, the compact 4 was heated in air at 350 ° C. for 8 hours to form the initial oxide film 31. After that, Table 1 together with the other moldings 4
After heating to the temperature shown in FIG. 1, the molten bonding metal 6 was impregnated with pressure by an apparatus as shown in FIG. FIG. 3 shows a schematic diagram of the structure of the molded body 4. An insulating film, which is a final oxide film 32 formed by the reaction between the initial oxide film 31 and the bonding metal 6, is observed. The final oxide film 32 has a film thickness and material etc.
As a result of measurement with a wire microanalyzer, some of the insulating films still contained iron oxide. After pressurizing and impregnating, samples (No. 1, 7 to 7) in which the final oxide film 32 formed simultaneously with the reduction of the initial oxide film 31 at the impregnation temperature were formed.
16) and a final oxide film 32 formed at a temperature lower than the impregnation temperature was formed as a sample. Initial oxide film 31 as a comparative example
Only but no bound metal was added. Next, heat treatment for removing the residual stress of the iron metal particles 2 was performed. This treatment is not necessary if the impregnation temperature is set to 750 ° C. or more and maintained at that temperature. The formed samples are all adjusted to be 80% by volume or more. Table 2 shows the measurement results of the magnetic permeability, the saturation magnetic flux density, and the resistance value, and the results of the impact test.

[0008]

[Table 2]

In this embodiment, N out of the numerical range is limited.
o. 7, no. 10, No. Except for the 13 samples and the comparative example, all the properties were satisfied and satisfied. No. In Nos. 14 and 15, since the thermal expansion coefficient of the bonding metal 6 is almost the same as that of iron, the influence of strain is small and the magnetic permeability is high. No. No. 2 has a high magnetic permeability because the iron-silicon alloy is hardly affected by strain. The sample having no iron oxide film at the beginning used as a comparative example is easily broken in the impact test. No. Sample No. 7 has a low magnetic permeability because the particle size of the magnetic powder 1 is small. No. The sample No. 10 has a low resistance because the thickness of the metal oxide is small. No. The sample No. 13 has a low saturation magnetic flux density because the final oxide film 32 of the magnetic powder 1 is too thick. Next, a molded article used for electric equipment was formed by the method of the present invention. Motor stator with outer diameter of 45mm, 500
Examples of a transformer yoke and a magnetic head of a square mm are shown in perspective views of FIGS. All of the electric devices obtained excellent molded articles without chipping and cracking. If a magnetic field is applied during molding, an anisotropic material having excellent magnetic properties in a certain direction can be obtained. In this way, the loss of electrical equipment used with AC voltage can be reduced, and the molding can be performed in a lump, which saves the labor of laminating silicon steel sheets and is expected to drastically reduce costs such as being suitable for complicated shapes. it can.

[0010]

As described above, according to the present invention, metal particles composed of iron or an iron alloy whose periphery is covered with a metal oxide mainly containing an element more easily oxidized than iron are combined with magnetic powder. Since a method of impregnating with a bonding metal to be bonded was used under pressure, a soft magnetic material excellent in mechanical strength, magnetic properties and high electric resistance was obtained. For this reason, there is an effect that the loss of the electric equipment used with the AC voltage can be reduced. Further, since the forming can be performed at a time, for example, labor for laminating silicon steel plates can be omitted, and a great cost reduction can be expected, such as being suitable for complicated shapes.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a manufacturing process for manufacturing a soft magnetic material of the present invention.

FIG. 2 is a perspective view showing a structure of a molded article of the present invention.

FIG. 3 is an enlarged schematic diagram showing the tissue structure of FIG. 2;

FIG. 4 is a perspective view of a motor stator formed by the present invention.

FIG. 5 is a perspective view of a transformer core formed by the present invention.

FIG. 6 is a perspective view of a magnetic head formed according to the present invention.

[Description of Signs] 1: Magnetic powder 2: Metal particles 3: Metal oxide 31: Initial oxide film 32: Final oxide film 4: Molded body 5: Void 6: Bonding metal 7: Container 8: Piston

Claims (19)

[Claims] 1. A magnetic powder comprising metal particles made of iron or an iron alloy having an average particle size of 10 to 400 μm, and a metal oxide covering the periphery of the metal particles and mainly containing an element more easily oxidized than iron, A soft magnetic material, comprising: a magnetic metal; and a bonding metal containing the metal oxide component. 2. The metal oxide has a thickness of 0.02 to 10 μm.
2. The soft magnetic material according to claim 1, wherein m and the volume of the magnetic powder is 80% or more of the whole. 3. The soft magnetic material according to claim 1, wherein the metal particles contain at least one of silicon and aluminum, and the weight ratio is 8% or less. 4. The method according to claim 1, wherein said metal particles are sendust or Fe--C.
The soft magnetic material according to any one of claims 1 to 3, which is an o-based alloy. 5. The soft magnetic material according to claim 1, wherein the metal oxide is any one of aluminum oxide, silicon oxide, and magnesium oxide. 6. The soft magnetic material according to claim 1, wherein a part of the metal oxide is an iron oxide. 7. The soft magnetic material according to claim 1, wherein the binding metal is aluminum, magnesium, or an alloy thereof. 8. The bonding metal according to claim 1, wherein the volume ratio of silicon is 40 to 70.
The soft magnetic material according to any one of claims 1 to 7, wherein the soft magnetic material is an aluminum alloy containing 0.1% by weight. 9. An average particle diameter having a metal oxide on the surface of 10 to 10.
A molded body is formed from a magnetic powder composed of 400 μm iron or iron alloy metal particles, and molten aluminum that is a bonding metal in a void portion of the molded body while the molded body is heated;
A method for producing a soft magnetic material, comprising: impregnating at least one of magnesium and an alloy thereof to obtain a soft magnetic composite. 10. A molded body is formed from a magnetic powder composed of iron or iron alloy metal particles having an average particle diameter of 10 to 400 μm, and the molded body is heated to 300 ° C. or more to oxidize the surface of the metal particle. A metal oxide is generated and, while the compact is heated, at least one of a binder metal such as molten aluminum, magnesium and an alloy thereof is impregnated into a void portion of the compact to obtain a soft magnetic binder. A method for producing a soft magnetic material, comprising: 11. The method for producing a soft magnetic material according to claim 9, wherein after the impregnation with the bonding metal, heat treatment is performed at 700 ° C. or higher to remove residual stress of the metal particles. 12. After the impregnation with the binding metal, a heat treatment is performed at a constant temperature of 300 ° C. or higher to reduce the metal oxide of iron formed on the surface of the metal particles with the binding metal. The method for producing a soft magnetic material according to any one of claims 9 to 11, wherein a metal oxide is formed around the metal particles. 13. The method for producing a soft magnetic material according to claim 9, wherein the pressure inside the compact is reduced when the magnetic powder is impregnated with the binding metal. 14. A motor stator comprising: an iron core having a plurality of slots; and a plurality of coils provided in the slots, wherein metal particles made of iron or an iron alloy having an average particle size of 10 to 400 μm are provided. A magnetic powder composed of a metal oxide whose main component is an element more easily oxidized than iron covering the periphery of the metal particles; and a binding metal that binds the magnetic powders together and contains a component of the metal oxide. A stator for an electric motor, wherein the soft magnetic material is used as an iron core of the stator. 15. A rotor for an electric motor having an iron core having a plurality of slots and a plurality of conductors provided in the slots, wherein metal particles made of iron or an iron alloy having an average particle size of 10 to 400 μm are provided. A magnetic powder composed of a metal oxide whose main component is an element more easily oxidized than iron covering the periphery of the metal particles; and a binding metal that binds the magnetic powders together and contains a component of the metal oxide. A rotor for an electric motor, wherein the soft magnetic material is used as an iron core of the rotor. 16. A transformer having an iron core and a coil wound around the iron core, wherein the average particle diameter is 10 to 4%.
A magnetic powder composed of metal particles made of iron or an iron alloy of 00 μm and a metal oxide mainly composed of an element that is more easily oxidized than iron that surrounds the metal particles; A transformer characterized in that a soft magnetic material having a binding metal containing an oxide component is used as an iron core. 17. A reactor comprising an iron core and a winding, wherein the main component is a metal particle made of iron or an iron alloy having an average particle diameter of 10 to 400 μm and an element covering the periphery of the metal particle, which is more easily oxidized than iron. A reactor, wherein a soft magnetic material having a magnetic powder composed of a metal oxide thus obtained and said magnetic powders bonded together and having a bonding metal containing a component of said metal oxide is used as an iron core. 18. A thyristor valve having an iron core and a winding, wherein a metal particle made of iron or an iron alloy having an average particle diameter of 10 to 400 μm and an element which is more easily oxidized than iron surrounding the metal particle. A thyristor characterized in that a soft magnetic material comprising a magnetic powder composed of a metal oxide made as described above, and a binding metal containing a component of the metal oxide, which binds the magnetic powders together, is used as a core. valve. 19. A magnetic head comprising an iron core and a winding, wherein a metal particle made of iron or an iron alloy having an average particle diameter of 10 to 400 μm and an element which is more easily oxidized than iron surrounding the metal particle. A magnetic powder comprising: a magnetic powder composed of a metal oxide; and a magnetic core comprising a soft magnetic material having the magnetic powder bonded to each other, and having a bonding metal containing a component of the metal oxide. head.