JPH10208923A - Composite magnetic material and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite magnetic material excellent in moldability and magnetic characteristics, especially core loss, by raising the heat treatment temperature of a high performance metal based dust core being employed in a choke coil, or the like, thereby removing stress sufficiently. SOLUTION: The composite magnetic material has a structure containing a metallic magnetic material and at least one kind of group A metals including Fe, Al, Ti, Sn, Si, Mn, Ta, Zr, Ca, Zn and alloys thereof. This composition realizes a composite magnetic material excellent in moldability and magnetic characteristics, especially core loss, in which stress can be removed sufficiently by raising the heat treatment temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite magnetic material used for a high-performance metal dust core such as a choke coil and a method for producing the same, and more particularly to a composite magnetic material used as a soft magnetic material for a magnetic core. The present invention relates to the manufacturing method.

[0002]

2. Description of the Related Art In recent years, miniaturization of electric and electronic devices has been progressing, and there has been a demand for magnetic materials of small size and high efficiency. Ferrite cores and dust cores are used as choke coils used at high frequencies. Among them, the ferrite core has a disadvantage that the saturation magnetic flux density is small.
On the other hand, a dust core formed by molding metal magnetic powder has an extremely large saturation magnetic flux density as compared with soft magnetic ferrite, which is advantageous for miniaturization. However, magnetic permeability and power loss were not superior to ferrite. In a core used for a choke coil or an inductor, if the core loss is large, the temperature rise of the core becomes large, and it is difficult to reduce the size.

[0003] The core loss of a dust core usually consists of hysteresis loss and eddy current loss. The eddy current loss increases in proportion to the square of the frequency and the square of the size in which the eddy current flows. Therefore, the surface of the magnetic powder particles is covered with an insulating powder for interlayer insulation to suppress the generation of the eddy current. On the other hand, as for the hysteresis loss, a molding pressure of usually 10 ton / cm ² or more is applied in order to increase the molding density of the dust core, so that the magnetic material is increased in strain, the magnetic permeability is deteriorated, and the hysteresis loss is increased.

[0004] In order to avoid this, a heat treatment is performed after molding to release the distortion. However, if the heat treatment temperature is 500
Since the temperature is required to be higher than or equal to ° C., an insulating binder which insulates the magnetic powder and keeps the binding between the powders is indispensable. Almost organic resins such as epoxy resins, phenolic resins, and PVC resins conventionally used as binders for green compacts cannot be used during high-temperature heat treatment, and require the use of inorganic binders and the like. .

Examples of the inorganic binder include silicate-based water glass, alumina cement disclosed in JP-A-1-215902, porosiloxane resin disclosed in JP-A-6-299144, and silicone resin disclosed in JP-A-6-342714.
Japanese Patent Application Laid-Open No. 8-45724 proposes a method of mixing a silicone resin and an organic titanium.

[0006]

However, these binders or insulating agents have poor binding properties at the time of molding or after heat treatment. Sintering of each other or diffusion of the binder component or the insulating component into the magnetic powder becomes remarkable,
Deterioration of characteristics as a magnetic material is caused.

An object of the present invention is to solve the above problems, and an object thereof is to provide a composite magnetic body which is excellent in moldability, enables high-temperature heat treatment for removing strain, and has excellent magnetic properties, particularly excellent core loss. It is.

[0008]

In order to achieve the above object, a composite magnetic material having a structure including a metal magnetic material and at least one or more kinds of Group A metals, wherein Fe and A are used as Group A metals.
1, Ti, Sn, Si, Mn, Ta, Zr, Ca, Zn
Metal or an alloy containing at least one of the above. Further, it is a composite magnetic body having a structure containing a metal magnetic body and at least one oxide of Group A metal. In the configuration of the present invention, it is preferable that the metal magnetic material has an average particle size of 100 μm or less, and is heat-treated at 500 ° C. or more after molding. Further, it is preferable that at least one or more of pure iron, Fe-Si system, Fe-Al-Si system, permalloy, and permendur are each contained as the metal magnetic material. This makes it possible to provide a composite magnetic material having excellent moldability, high-temperature heat treatment for removing strain, and excellent magnetic properties, particularly excellent core loss.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION
A composite magnetic material having a structure including a metal magnetic material and at least one or more kinds of Group A metals, wherein the Group A metals are Fe, Al, T
It is a single metal or an alloy containing at least one of i, Sn, Si, Mn, Ta, Zr, Ca, and Zn. Group A metal has high ductility, so it undergoes plastic deformation when mixed with a metal magnetic material and molded, and can be molded without reducing the amount of binder as a binder or at all, and because molding pressure can be reduced. Also, distortion during molding is reduced, and hysteresis loss is reduced.
In addition, it goes without saying that similar effects can be obtained with metals, alloys, amorphous metals and the like having excellent ductility.

According to a second aspect of the present invention, there is provided a composite magnetic material having a structure containing a metal magnetic material and at least one oxide of a Group A metal. In addition, the metal of group A has a strong reducing property, deprives other oxides or oxygen of the atmosphere, and oxidizes itself to become a stable oxide of group A metal, insulates the periphery of the metal magnetic powder, and reduces eddy current loss. Can be reduced.

According to a third aspect of the present invention, there is provided the composite magnetic body according to the first or second aspect, wherein the metal magnetic body has an average particle diameter of 100 μm or less. The eddy current loss increases in proportion to the square of the frequency and the square of the size in which the eddy current flows.If the surface of the magnetic powder is covered with an insulator, the eddy current depends on the particle size of the metal magnetic powder. The finer the eddy current loss is.

For example, a choke coil for harmonic distortion countermeasure has a current measurement frequency of 50 kHz and a measured magnetic flux density of 0.1 T
Therefore, a core loss of 1000 kW / m ³ or less, and more preferably 500 kW / m ³ or less is desired. For that purpose, in order to reduce the eddy current loss of 50 kHz or more, at least an average particle diameter of 100 μm or less is required by theoretical calculation, and more preferably 50 μm or less. Further, if an oxide film having a thickness of 5 nm or more is formed on the surface of the metal magnetic powder, the insulating property is more reliable and the eddy current loss is more effectively reduced.

[0013] The invention according to claim 4 of the present invention is characterized in that pure iron, Fe-Al-Si, Fe-Si,
3. The composite magnetic material according to claim 1, wherein the composite magnetic material contains at least one of permalloy and permendur. These metal magnetic materials are
Both the saturation magnetic flux density and the magnetic permeability are high, and can be easily obtained in atomized powder, pulverized powder, etc. It goes without saying that it is effective.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a composite magnetic material obtained by molding a mixture containing a metal magnetic material and at least one or more Group A metals and then performing a heat treatment at 500 ° C. or more. It was done. Usually 10ton
Since a molding pressure of / cm ² or more is applied, the strain increases as the magnetic material, the magnetic permeability deteriorates, and the hysteresis loss increases. Therefore, a heat treatment of 500 ° C. or more is performed after molding to release the distortion, thereby reducing the hysteresis loss.

However, the strain relief temperature differs depending on the metal magnetic material, and is preferably 600 ° C. or more for the Fe—Al—Si system, 700 ° C. or more for the Fe system, and usually 700 ° C. or higher for the metal magnetic material. Organic resins such as epoxy resins, phenolic resins, and PVC resins, or inorganic resins such as water glass and inorganic silicone resins, which are conventionally used as binders, have a high heat treatment temperature, especially when the temperature becomes 700 ° C. or higher, the magnetic powder The sintering of each other or the diffusion of the binder component or the insulating component into the magnetic powder becomes remarkable, the characteristics of the magnetic material deteriorate, and both the hysteresis loss and the eddy current loss increase.

In the present invention, the starting material of the insulator is A
The high-temperature heat treatment of 500 ° C. or more is possible because of the group metal, and the oxide of the group A metal is stable at the time of molding or heat treatment. Therefore, there is little deterioration of the characteristics, and the hysteresis loss can be greatly reduced.

The invention according to claim 6 of the present invention is obtained by molding a mixture containing at least one kind of each of a metal magnetic material, at least a Group A metal and an oxide B, and then performing a heat treatment at 500 ° C. or more. In the method for producing a composite magnetic material, the oxide B is an oxide having higher oxidation generation energy than the group A metal used. Oxidation Energy (Electrochemical Association, Maruzen Co., Ltd. "Electrochemical Handbook No. 4
Plates, p. 128, 129) show the free energy required when an element reacts with oxygen to form an oxide. The smaller this value is, the more easily it becomes an oxide, and the oxide is stable.

Therefore, when a metal having a low oxidation generation energy reacts with an oxide having a higher oxidation generation energy, the oxide is reduced and the metal itself becomes an oxide on the contrary. Therefore, the oxide B differs depending on the group A metal to be added at the same time. The aluminothermite method for the reduction reaction of Al is as follows:
This is a typical example, for example, the following reaction occurs.

2/5 V ₂ O ₅ +4/3 Al = 4/5 V + 2
/ 3Al ₂ O ₃ +496.9 kJ Further, since such a local high temperature is generated, the mechanical strength of the magnetic body after the heat treatment is also improved. Further, the degree of oxidation of the group A metal can be controlled by changing the amount of the oxide B.

Hereinafter, specific examples of the present invention will be described. (Embodiment 1) As shown in Table 1, with respect to a sample in which a metal powder or a binder is mixed with 100 parts by weight of a metal magnetic powder, 10 parts by weight and 3 parts by weight are mixed by a raikai machine, respectively. Mixed. The mixed powder was molded by a uniaxial press to a molding density of 9
Change the molding pressure so that it becomes 0% or more, outer diameter 25m
m, an inner diameter of 15 mm and a thickness of about 10 mm were obtained in a toroidal shape.

The pure iron of the metal magnetic material used has a purity of 9%.
9.6%, Fe-Al-Si has a sendust composition of S
i-9%, Al-5%, balance Fe and Fe-Si are Si-
3.5%, balance Fe, permalloy is Ni-78.5%,
Remaining Fe, Permendur Co-50%, Remaining Fe
Each of which is an atomized powder having an average particle size of 50 μm or less.
It is formed to a thickness of 10 to 10 nm.

The magnetic permeability was measured at a frequency of 10 kHz with an LCR meter, and the core loss was measured at a frequency of 50 kHz with a measured magnetic flux density of 0.
The measurement was performed at 1T. The results are shown in (Table 1).

[0023]

[Table 1]

As is evident from the results shown in Table 1, the sample containing the Group A metal required a lower molding pressure and reduced core loss. Further, Mg and Nd other than the Group A metals were hardly plastically deformed, so that the formed body could not be maintained. It goes without saying that the same effect can be obtained even with an alloy containing at least one or more kinds of Group A metals other than the examples, or a solid solution or amorphous.

(Embodiment 2) As shown in Table 2, 10 parts by weight and 3 parts by weight of a metal magnetic powder mixed with 100 parts by weight of a metal powder or a binder were added to a raikai machine. And mixed. The mixed powder is formed with a uniaxial press at a molding pressure of 6 ton / cm.
^{In step 2} , a toroidal shaped body having an outer diameter of 25 mm, an inner diameter of 15 mm, and a thickness of about 10 mm was obtained, and was heat-treated while controlling the atmosphere at the temperatures shown in Table 2. The used Fe-S
i is Si-3.5% and is a pulverized powder having an average particle size of 50 μm or less.

The magnetic permeability is measured at a frequency of 10 kHz with an LCR meter, and the core loss is measured at a frequency of 50 kHz with a measured magnetic flux density of 0.
The measurement was performed at 1T. The results are shown in (Table 2).

[0027]

[Table 2]

As is evident from the results shown in Table 2, the sample mixed with Group A metal can be heat-treated at a high temperature of 500 ° C. or more, and the core loss is reduced. Also preferably 700 ° C.
From the above, it can be seen that it is further reduced. Further, when the composition of the molded body after the heat treatment was analyzed by X-ray fluorescence, it was confirmed that the metal of Group A was in the form of the respective oxide.
Needless to say, other metal magnetic powders and Group A metals have similar effects.

(Embodiment 3) As shown in Table 3, 10 parts by weight of metal powder was mixed and mixed with 100 parts by weight of metal magnetic powder using a raikai machine. The mixed powder was formed with a uniaxial press at a molding pressure of 6 ton / cm ² and an outer diameter of 2
A toroidal shaped body having a size of 5 mm, an inner diameter of 15 mm, and a thickness of about 10 mm was obtained, and heat-treated at 800 ° C. while controlling the atmosphere. The permalloy used was Ni-78.5%,
The remainder was atomized powder of Fe, and the average particle size was changed as shown in (Table 3).

The permeability was measured at a frequency of 10 kHz with an LCR meter, and the core loss was measured at a frequency of 50 kHz with a measured magnetic flux density of 0.
The measurement was performed at 1T. The results are shown in (Table 3).

[0031]

[Table 3]

As is evident from the results in Table 3, the average particle size of the metal magnetic powder is 100 μm or less and the core loss is 100%.
It turns out that it is 0 kW / m ³ or less. More preferably, the average particle size of the magnetic powder is 50 μm or less. Needless to say, other metal magnetic powders and Group A metals have similar effects.

(Embodiment 4) As shown in Table 4, 7 parts by weight and 3 parts by weight of a metal powder or an oxide were mixed and mixed with 100 parts by weight of a metal magnetic powder using a raikai machine. The mixed powder is formed by a uniaxial press at a molding pressure of 8 ton / cm ² , an outer diameter of 25 mm and an inner diameter of 15 m.
m, a toroidal shaped body having a thickness of about 10 mm was obtained.
The heat treatment was performed at 0 ° C. while controlling the atmosphere. Also,
The pure iron of the magnetic metal used was carbonyl iron powder having a purity of 99.6% and an average particle diameter of 50 μm or less.

The magnetic permeability is measured at a frequency of 10 kHz with an LCR meter, and the core loss is measured at a frequency of 50 kHz with a measured magnetic flux density of 0.
The measurement was performed at 1T. The results are shown in (Table 4).

[0035]

[Table 4]

The energy of oxidation formation is C in the following order:
u>Bi>V>Nb>B>Al>Mg> Ca. Therefore,
An oxide having a higher oxidation generation energy than Al used (C
uO, Bi ₂ O ₃ , V ₂ O ₅ , Nb ₂ O ₅ , and B ₂ O ₃ ) achieve low core loss and use an oxide (MgO, CaO) having lower oxidation generation energy than Al. Is that Al is unlikely to exist as a stable oxide, so it diffuses into the magnetic powder during high-temperature heat treatment and deteriorates the magnetic properties.
It became clear from the results of (Table 4) and analysis of fluorescent X-rays and the like. Needless to say, a similar effect can be obtained even when a combination of another metal magnetic powder, a Group A metal and an oxide having higher oxidation generation energy is used.

[0037]

As described above, according to the present invention, the group A metal is plastically deformed during molding, assists in binding metal magnetic powders, and when forming or heat-treating after molding, the surrounding oxide or Oxygen is removed from the atmosphere to form a stable oxide insulator. Therefore, the insulation around the metal magnetic powder is reliably insulated and the eddy current loss is reduced, and at the same time, since this insulator is made of metal, sufficient heat treatment for removing strain at a high temperature of 500 ° C. or more is possible, and the hysteresis loss is reduced. And overall core loss can be significantly reduced.

Claims (6)

[Claims] 1. A composite magnetic material having a structure containing at least one kind of a metal magnetic material and at least one kind of a group A metal (however, the group A metal is Fe, Al, Ti, Sn, Si, Mn, Ta, Zr,
It is a simple metal or alloy containing at least one of Ca and Zn. ). 2. A composite magnetic material having a structure containing at least one kind of a metal magnetic material and at least one oxide of a Group A metal (however, A
Group metals are Fe, Al, Ti, Sn, Si, Mn, T
It is a simple metal or an alloy containing at least one of a, Zr, Ca, and Zn. ). 3. The composite magnetic body according to claim 1, wherein the average particle size of the metal magnetic body is 100 μm or less. 4. As the metal magnetic material, pure iron, Fe—Al—
The composite magnetic material according to claim 1, wherein the composite magnetic material contains at least one of Si-based, Fe—Si-based, permalloy, and permendur. 5. A method for producing a composite magnetic material obtained by molding a mixture containing a metal magnetic material and at least one or more Group A metals and then performing a heat treatment at 500 ° C. or higher (where Group A metals are Fe , Al, Ti, Sn, Si, M
It is a simple metal or an alloy containing at least one of n, Ta, Zr, Ca, and Zn. ). 6. A method for producing a composite magnetic material obtained by molding a mixture containing at least one kind of each of a metal magnetic material, at least a Group A metal and an oxide B, and then heat-treating the mixture at 500 ° C. or more. Group metals are Fe, Al, Ti,
It is a simple metal or an alloy containing at least one of Sn, Si, Mn, Ta, Zr, Ca, and Zn. The oxide B is an oxide having higher oxidation generation energy than the group A metal used. ).