JPH11260618A - Composite magnetic material, its manufacture, and fe-al-si soft magnetic alloy powder used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composite magnetic material which can decrease the core loss and heat generation of a core and can increase the permeability of the core, by making the temperature efficient of the core loss at a room temperature negative by mixing Fe-Al-Si soft magnetic alloy powder having a positive magnetostriction constant at the room temperature in the magnetic material. SOLUTION: A composite magnetic material contains Fe-Al-Si magnetic alloy powder having a positive magnetostriction constant λ at a room temperature to make the temperature coefficient of the core loss of a core negative at the room temperature. It is preferable that the minimum temperature of the composite magnetic material at which the core loss becomes the minimum is >=80 deg.C, and that the soft magnetic alloy powder contains 4.5-8.5 wt.% Al, 7.5-9.5 wt.% Si, and the balance Fe. It is also preferable to manufacture the soft magnetic alloy powder by gas atomization, water atomization, or pulverization after alloying and to adjust the average grain size of the powder between 1 μm and 100 μm.

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 transformer core, a choke coil or a magnetic head, a method for producing the same, and an Fe-Al-Si soft magnetic alloy powder used for the composite magnetic material. Things.

[0002]

2. Description of the Related Art In recent years, miniaturization of electric and electronic devices has been progressing.
A small and highly efficient magnetic material is required, and a ferrite core and a dust core are known as choke coils used in a high frequency range. Of these, ferrite cores have the disadvantage of low saturation magnetic flux density, while dust cores made by molding metal magnetic powder have significantly higher saturation magnetic flux densities than ferrite cores. Which is advantageous in terms of miniaturization.

However, dust cores are not superior to ferrite cores in terms of magnetic permeability and power loss.
For use in choke coils and inductors,
One of the disadvantages is that the core loss is large and the temperature rise of the core is large, so that downsizing is difficult.

In general, the core loss of a dust core generally consists of hysteresis loss and eddy current loss. The eddy current loss is proportional to the square of the frequency and the size of the eddy current flowing, that is, the square of the eddy current path length, respectively. Increase. In order to suppress this, the surface of the magnetic powder is covered with an electrically insulating resin or the like, thereby suppressing the generation of eddy current.

On the other hand, as for the hysteresis loss, since the molding of the dust core is usually performed at a molding pressure of 5 ton / cm ² or more, the distortion as the magnetic material increases, the magnetic permeability also deteriorates, and the hysteresis loss increases. Tend. As means for releasing the distortion in order to avoid this tendency, for example, JP-A-6-342714, JP-A-8-3710
No. 7, Japanese Patent Application Laid-Open No. 9-125108, followed by heat treatment after molding.

[0006]

However, the dust core using the conventional Fe-Al-Si alloy powder has a disadvantage that the core loss increases with the temperature.
That is, if the temperature coefficient of the core loss is positive near room temperature, the transformer or the choke coil generates heat due to the core loss during actual use. As a result, the temperature rises, the core loss due to this temperature rise increases, and the heat generation increases,
There was a problem that thermal runaway was caused by repeating this. In order to prevent such a phenomenon, it is extremely important that, when actually used, the dust core has a temperature characteristic such that the core loss is minimized at a temperature around 80 ° C to 100 ° C. Met.

In general, as shown in FIGS. 2 and 3, a Fe—Al—Si alloy has a composition having a crystal magnetic anisotropy constant K ≒ 0 and a magnetostriction constant λ ≒ 0, that is, 9.6% S
i shows a sharp magnetic permeability peak near the composition of 5.5% Al and the balance being Fe. Compositions in this range are usually called sendust. Conventionally, various composite magnetic materials using Fe-Al-Si alloy powders have been proposed, for example, as described in JP-A-6-342714 and JP-A-8-37 mentioned above.
No. 107, Japanese Patent Application Laid-Open No. 9-125108 also proposes this kind of technology. However, none of the proposals mentions the description of core loss and temperature characteristics.

The temperature characteristic of the core loss is determined by the hysteresis loss behavior, that is, the temperature characteristic of the magnetic permeability. Conventional ferrite exhibits a maximum at a certain magnetic permeability, and the loss becomes minimum at this temperature. This means that the crystal magnetic anisotropy constant K becomes zero at this temperature, and at this temperature the domain wall movement becomes easiest. Therefore, it is considered that the hysteresis loss is reduced.

On the other hand, a powder magnetic core using an Fe-Al-Si soft magnetic alloy powder has a particularly large output because the core loss monotonously increases at room temperature or higher, as in the conventional example shown in FIG. It has been difficult to use in transformers and the like.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and provides a composite magnetic body having low core loss, low heat generation, and high magnetic permeability, a method for producing the same, and a magnetic material usable for the composite magnetic body. It is intended to provide an alloy powder.

[0011]

The composite magnetic material of the present invention comprises:
The sign of the magnetostriction constant λ is positive at room temperature.
By using the Si-based soft magnetic alloy powder, the temperature coefficient of the core loss at room temperature is made negative. With this configuration, it is possible to obtain a composite magnetic material having a characteristic of low core loss in a high frequency region and having high magnetic permeability.

In the composite magnetic material of the present invention, the minimum temperature at which the core loss is minimized is preferably 80 ° C. or higher. Further, the Fe-Al-Si soft magnetic alloy powder is 4.5% ≦ Al ≦ 8.5%, 7.5% ≦ Si ≦ 9% by weight.
It is preferable that the composition be 5% and the balance be a composition containing Fe as a main component.

As a result of the research, the present inventors have found that Fe-Al-
In the case of a composite magnetic material using a Si-based soft magnetic alloy powder, the crystal magnetic anisotropy constant K, as conventionally known, is not the main factor that governs the temperature characteristics of core loss, and has not received much attention. It is found that the magnetostriction constant λ is dominant and that the temperature coefficient of core loss has a negative slope when the sign of the magnetostriction constant λ is positive at room temperature (about 20 to 30 ° C.). And 4.5% ≦ Al ≦ 8.5% in weight%,
7.5% ≦ Si ≦ 9.5%, Fe-Al-Si based soft magnetic alloy powder whose main component is Fe when used, has high magnetic permeability, low core loss, and excellent temperature characteristics. And more preferably 5.0% ≦ Al ≦ 6.5 by weight.
%, 8.2% ≦ Si ≦ 9.2%, with the balance being Fe—Al—Si based soft magnetic alloy powder containing Fe as a main component.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The composite magnetic material of the present invention uses a Fe-Al-Si soft magnetic alloy powder having a positive magnetostriction constant λ at room temperature to reduce the temperature coefficient of core loss at room temperature. This is a composite magnetic material. Since the composite magnetic material of the present invention can have a negative temperature coefficient of core loss, excellent magnetic characteristics with low core loss and high magnetic permeability can be obtained even in a high frequency region. In the composite magnetic body of the present invention, the minimum temperature at which the core loss is minimized is preferably 80 ° C. or higher.

[0015] The composite magnetic material of the present invention comprises Fe-Al-Si.
It is composed of a main component that is a soft magnetic alloy powder and a residue after heat treatment of an insulating binder or an insulating component such as an impregnating resin or pores. Content of magnetic alloy powder is 70-99% by volume
Is preferably within the range. The composition of the soft magnetic alloy powder is 4.5% ≦ Al ≦ 8.5% by weight,
It is preferable that 5% ≦ Si ≦ 9.5% and the balance be Fe. The soft magnetic alloy powder may contain a small amount of impurities or additives that do not adversely affect the magnetic properties. In addition, this composite magnetic material has a main component of Fe-A
Other magnetic powders may be mixed on the l-Si soft magnetic alloy powder.

The soft magnetic alloy powder is preferably a powder obtained by a gas atomizing method, a water atomizing method, or pulverization after alloying. The shape of the powder may be spherical, flat, or polygonal. The average particle size of the powder is preferably in the range of 1 to 100 μm, and more preferably in the range of 1 to 50 μm. If the average particle size is less than 1 μm, the molding density is reduced, and the magnetic permeability is undesirably reduced. This soft magnetic alloy powder is preferably covered with an oxide film having a thickness of 5 nm or more. This coating improves insulation and further reduces eddy current loss.

The method of manufacturing a composite magnetic material according to the present invention is characterized in that a Fe--Al--Si soft magnetic alloy powder having a positive magnetostriction constant λ at room temperature is mixed with an electrically insulating binder and compression-molded. 5
The heat treatment is performed at a temperature of from 00 ° C to 900 ° C. According to this method of manufacturing a composite magnetic body, heat treatment after compression molding can reduce eddy current loss and hysteresis loss, and can obtain a composite magnetic body having more stable and excellent magnetic properties. .

The insulating binder in the production method of the present invention is preferably at least one of an epoxy resin, a phenol resin, a vinyl chloride resin, a butyral resin, and an organic silicone resin. Since the heat treatment is performed at a temperature of 500 ° C. or more and 900 ° C. or less, it is more preferable that the binder component diffuses little into the magnetic alloy powder. The heat treatment may be performed in the air, but is preferably performed in a non-oxidizing atmosphere from the viewpoint of preventing oxidation of the metal.

After the heat treatment, it is preferable to impregnate with an insulating impregnating agent. This is because, when heat treatment is performed at a temperature of 500 ° C. or more, the binder such as resin is decomposed, so that the mechanical strength of the composite magnetic body is reduced. Therefore, by impregnating with an insulating impregnating agent after the heat treatment, it is possible to improve the core strength, prevent rust of the metal magnetic material, increase the surface resistance, and the like. Further, the impregnating agent enters into the inside by vacuum impregnation, which is more preferable.

The Fe—Al—Si soft magnetic alloy powder of the present invention has a composition of 4.5% ≦ Al ≦ 8.5% by weight,
It is preferable that 7.5% ≦ Si ≦ 9.5% and the balance be Fe, and that the oxygen amount be 1000 ppm or more and 8000 ppm or less, and the sign of the magnetostriction constant λ be positive at room temperature. By using this soft magnetic alloy powder, the temperature coefficient of core loss can be made negative, so that excellent magnetic characteristics with low core loss and higher magnetic permeability can be obtained even in a high frequency region. When the oxygen amount is 1000 ppm or more, the eddy current loss is further reduced. It is considered that the eddy current loss was reduced because the resistance value of the metal magnetic powder increased with the oxygen content. On the other hand, the oxygen amount is 8000
If the amount exceeds ppm, the hysteresis loss increases,
The overall core loss increases.

Hereinafter, specific examples of the present invention will be described. (Embodiment 1) Hereinafter, a composite magnetic body according to Embodiment 1 of the present invention will be described.

The Fe—Al—Si soft magnetic alloy powder according to the present embodiment was produced by the water atomization method so as to have the final composition shown in Table 1. The oxygen content of all the powders was from 2000 ppm to 3000 ppm. This F
The e-Al-Si soft magnetic alloy powder is classified by a sieve so as to have an average particle size of 50 μm.
2 parts by weight of butyral resin as an insulating binder was added to 0 parts by weight and mixed. The mixed powder was formed by a uniaxial press machine at a molding pressure of 10 ton / cm ² , an outer diameter of 25 mm and an inner diameter of 15 mm.
A toroidal shaped body having a thickness of about 10 mm and a thickness of about 10 mm was formed. Then, after heat-treating at a temperature of 690 ° C. in N ₂ , a sample was prepared by impregnation with a silicone resin.

The permeability was measured at a frequency of 10 kHz using an LCR meter, and the core loss was measured at 20 ° C. to 120 ° C. at a measurement frequency of 50 kHz and a measured magnetic flux density of 0.1 T using an AC BH curve measuring machine. The measurement was carried out every 20 ° C. up to the temperature including the temperature characteristics. The characteristics at the minimum loss temperature are shown in (Table 1). However, when the minimum loss temperature is equal to or higher than 120 ° C or equal to or lower than 20 ° C, the minimum loss temperature is set to 120 ° C or 2 ° C, respectively.
It shows core loss and magnetic permeability at 0 ° C. In the case of the choke coil for the active filter against harmonic distortion in the present embodiment, as shown in (Table 1), the measurement frequency is 50 k
Hz, core loss 1000 at measured magnetic flux density 0.1T
Satisfactory characteristics of kW / m ³ or less, magnetic permeability of 50 or more, and minimum loss temperature of 80 ° C. or more could be obtained.

As is clear from the results shown in Table 1,
4.5% ≦ Al ≦ 8.5% by weight, 7.5% ≦ Si ≦
9.5%, the remainder being Fe-Al-Si containing Fe as a main component
By using a system soft magnetic alloy powder, a high magnetic permeability, a low core loss, and excellent temperature characteristics can be provided. More preferably, 5.0% ≦ Al ≦ 6.5 by weight.
%, 8.2% ≦ Si ≦ 9.2%, with the balance being Fe—Al—Si-based soft magnetic alloy powder containing Fe as a main component, a further excellent effect can be obtained.

[0025]

[Table 1]

(Embodiment 2) Next, Embodiment 2 of the present invention will be described.

In the final composition, 6.0 wt% of Al, S
A soft magnetic alloy powder having i of 9.0 wt% and the remaining main component of Fe was produced by an ingot grinding method. All powders have an oxygen content of 1000 ppm to 2000 ppm, and are classified by a sieve or an air classification method so as to have an average particle size shown in Table 2, and an insulating binder is added to 100 parts by weight of the metal magnetic powder. Was added and mixed with 5 parts by weight of an organic silicone resin. The mixed powder was subjected to a uniaxial press at a molding pressure of 7 ton / cm ² , an outer diameter of 25 mm, an inner diameter of 15 mm, and a thickness of about 1
A 0 mm toroidal shaped compact was formed. afterwards,
After heat treatment at 720 ° C. in N ₂ , a sample was prepared by impregnation with an epoxy resin.

The permeability was measured at a frequency of 10 kHz using an LCR meter, and the core loss was measured using an AC BH
Using a curve measuring machine, the measurement was performed at a measurement frequency of 50 kHz and a measurement magnetic flux density of 0.1 T from 20 ° C. to 120 ° C. every 20 ° C., including the temperature characteristics, and the characteristics at the minimum loss temperature are shown in (Table 2). However, the minimum loss temperature is ≧ 120
° C or ≤20 ° C, 120 ° C and 20 ° C respectively
It shows the core loss and magnetic permeability at ° C. In the case of the choke coil for the active filter against harmonic distortion in the present embodiment, the measurement frequency is 50 kHz as shown in (Table 2).
z, core loss 1000k at measured magnetic flux density 0.1T
W / m ³ or less, permeability 50 or more, and minimal loss temperature 8
Satisfactory characteristics of 0 ° C. or higher could be obtained.

As is clear from the results shown in (Table 2),
The core loss can be reduced by setting the average particle size of the magnetic powder to 1 μm or more and 100 μm or less, and preferably, the core loss can be further reduced by setting the average particle size to 1 μm or more and 50 μm or less.

[0030]

[Table 2]

(Embodiment 3) Next, Embodiment 3 of the present invention will be described.

In the final composition, Al is 5.8 wt%, S
A powder having an average particle diameter of 30 μm was prepared by a water atomization method using a soft magnetic alloy having i of 8.6 wt% and the remaining main component of Fe. To 100 parts by weight of the metal magnetic powder, 1 part by weight of butyral resin as an insulating binder and 0.5 parts by weight of TiO ₂ having an average particle size of 1 μm as a spacing control material were added and mixed. The mixed powder is degassed, mixed, and pulverized to obtain a granulated powder having a particle diameter of 500 μm or less by a uniaxial press at a molding pressure of 12 ton / cm ² and 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 formed. After debinding in air at 450 ° C,
The sample was heat-treated at 730 ° C. in N ₂ and further impregnated with an epoxy resin to prepare a sample.

The permeability was measured at a frequency of 10 kHz using an LCR meter, and the core loss was measured using an AC BH
Using a curve measuring machine, measurement was performed at a measurement frequency of 50 kHz and a measurement magnetic flux density of 0.1 T from 20 ° C. to 120 ° C. every 20 ° C., including the temperature characteristics. The characteristics at the minimum loss temperature are shown in Table 3. However, the minimum loss temperature is ≧ 120
° C or ≤20 ° C, 120 ° C and 20 ° C respectively
It shows the core loss and magnetic permeability at ° C. In the case of the choke coil for the active filter for harmonic distortion countermeasures in the present embodiment, the measurement frequency is 50 kHz as shown in (Table 3).
z, core loss 1000k at measured magnetic flux density 0.1T
W / m ³ or less, permeability 50 or more, and minimal loss temperature 8
Satisfactory characteristics of 0 ° C. or higher could be obtained.

[0034]

[Table 3]

As is clear from the results shown in (Table 3),
By setting the amount of oxygen to 1000 ppm or more and 8000 ppm or less, high magnetic permeability and low core loss can be obtained.

(Embodiment 4) Next, Embodiment 4 of the present invention will be described.

The Fe—Al—Si soft magnetic alloy powder according to the present embodiment was produced by a gas atomization method so as to have the final composition shown in (Table 4). This Fe-Al
The Si-based soft magnetic alloy powder was classified by a sieve so as to have an average particle diameter of 60 μm, and 2 parts by weight of butyral resin as an insulating binder was added to 100 parts by weight of the metal magnetic powder and mixed. The mixed powder was subjected to uniaxial pressing at a molding pressure of 7 ton / cm ² at an outer diameter of 25 mm, an inner diameter of 15 mm, and a thickness of about 1 mm.
A 0 mm toroidal shaped compact was formed. And
After heat treatment at 710 ° C. in N ₂ , a sample was prepared by impregnation with a silicone resin.

The magnetic permeability was measured at a frequency of 10 kHz using an LCR meter, and the core loss was measured at a measuring frequency of 50 kHz and a measuring magnetic flux density of 0.1 T at 20 ° C. to 120 ° C. using an AC BH curve measuring machine. Up to 20 ° C., including temperature characteristics, the characteristics at the minimum loss temperature are shown in (Table 4). However, when the minimum loss temperature is equal to or higher than 120 ° C or equal to or lower than 20 ° C, the minimum loss temperature is set to 120 ° C or 2 ° C, respectively.
It shows core loss and magnetic permeability at 0 ° C. In the case of the choke coil for the active filter for harmonic distortion countermeasures in the present embodiment, the measurement frequency is 50 k as shown in (Table 4).
Hz, core loss 1000 at measured magnetic flux density 0.1T
Satisfactory characteristics of kW / m ³ or less, magnetic permeability of 50 or more, and minimum loss temperature of 80 ° C. or more could be obtained.

As is clear from the results shown in (Table 4),
4.5% ≦ Al ≦ 8.5%, 7.5% ≦ Si by weight%
≤9.5%, the remainder being Fe-Al-S whose main component is Fe
When the i-based soft magnetic alloy powder is used, it has high magnetic permeability, low core loss, and excellent temperature characteristics, and more preferably, 5.0% ≦ Al ≦ 6.5%, 8.2 by weight. % ≦ Si ≦ 9.
Even better effects can be obtained by using an Fe-Al-Si soft magnetic alloy powder containing 2% Fe as the main component.

[0040]

[Table 4]

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described.

In the final composition, Al was 6.0 wt%, S
A soft magnetic alloy powder in which i is 9.0 wt% and the remaining main component is Fe is produced by a gas atomizing method, and classified by a sieve so as to have an average particle diameter shown in (Table 5). 3 parts by weight of an organic silicone resin as an insulating binder was added to and mixed with the parts by weight. The mixed powder was pressed by a uniaxial press at a molding pressure of 9 ton / cm ² and an outer diameter of 25 m.
m, an inner diameter of 15 mm and a thickness of about 10 mm were formed in a toroidal shaped body. After heat treatment at 730 ° C. in N ₂ , the sample was impregnated with an epoxy resin to prepare a sample.

The magnetic permeability was measured at a frequency of 10 kHz using an LCR meter, and the core loss was measured at a measuring frequency of 50 kHz and a measured magnetic flux density of 0.1 T at 20 ° C. to 120 ° C. using an AC BH curve measuring machine. Up to 20 ° C., including temperature characteristics, the characteristics at the minimum loss temperature are shown in (Table 5). However, the minimum loss temperature is ≧ 120
° C or ≤20 ° C, 120 ° C and 20 ° C respectively
It shows the core loss and magnetic permeability at ° C. In the case of the choke coil for the active filter for harmonic distortion countermeasures in the present embodiment, the measurement frequency is 50 kHz as shown in (Table 5).
z, core loss 1000k at measured magnetic flux density 0.1T
W / m ³ or less, permeability 50 or more, and minimal loss temperature 8
Satisfactory characteristics of 0 ° C. or higher could be obtained.

As is clear from the results shown in (Table 5),
The core loss can be reduced by setting the average particle size of the magnetic powder to 100 μm or less, and the core loss can be further reduced by setting the average particle size to 50 μm or less.

[0045]

[Table 5]

Embodiment 6 Next, Embodiment 6 of the present invention will be described.

In the final composition, Al was 5.8 wt%, S
Using a soft magnetic alloy in which i is 8.6 wt% and the remaining main component is Fe, the average particle diameter is 40 μm by gas atomization.
Powder was prepared. To 100 parts by weight of the metal magnetic powder, 1 part by weight of butyral resin as an insulating binder and 1 part by weight of MgO having an average particle size of 1 μm as a spacing control material were added and mixed. The mixed powder is degassed and mixed, and the granulated powder having a particle size of 500 μm or less obtained by pulverization is subjected to a uniaxial press at a molding pressure of 10 ton / cm ² , an outer diameter of 25 mm and an inner diameter of
A toroidal shaped body having a thickness of about 10 mm and a thickness of about 10 mm was formed. After debinding in air at a temperature of 450 ° C., heat treatment was performed in N ₂ under the heat treatment conditions shown in (Table 6). Thereafter, the sample was impregnated with an epoxy resin to prepare a sample.

The magnetic permeability is measured at a frequency of 10 kHz using an LCR meter, and the core loss is measured at a measuring frequency of 50 kHz and a measured magnetic flux density of 0.1 T at 20 ° C. to 120 ° C. using an AC BH curve measuring machine. Up to 20 ° C., including the temperature characteristics, the characteristics at the minimum loss temperature are shown in (Table 6). However, the minimum loss temperature is ≧ 120
° C or ≤20 ° C, 120 ° C and 20 ° C respectively
It shows the core loss and magnetic permeability at ° C. In the case of the choke coil for the active filter against harmonic distortion in the present embodiment, the measurement frequency is 50 kHz as shown in (Table 6).
z, core loss 1000k at measured magnetic flux density 0.1T
W / m ³ or less, permeability 50 or more, and minimal loss temperature 8
Satisfactory characteristics of 0 ° C. or higher could be obtained.

[0049]

[Table 6]

As is clear from the results shown in Table 6,
The core loss can be reduced by setting the heat treatment temperature to 500 ° C. or more and 900 ° C. or less, and the core loss can be further reduced by setting the heat treatment temperature to 650 ° C. to 800 ° C.

Embodiment 7 Next, Embodiment 7 of the present invention will be described.

In the final composition, Al was 7.5 wt%, S
A soft magnetic alloy powder in which i is 8.5 wt% and the remaining main component is Fe, and A as a comparative example having a conventional sendust composition
1 is 5.4 wt%, Si is 9.6 wt%, and the remaining main component is Fe. A soft magnetic alloy powder is produced by a gas atomization method, and the average particle diameter of each alloy powder is 40.
The particles were classified by a sieve so as to have a thickness of μm, and 4 parts by weight of an organic silicone resin as an insulating binder was added to 100 parts by weight of the metal magnetic powder and mixed. The mixed powder was formed into a toroidal shaped body having an outer diameter of 25 mm, an inner diameter of 15 mm, and a thickness of about 10 mm at a molding pressure of 10 ton / cm ² by a uniaxial press. Then, after heat treatment at a temperature of 720 ° C. in N ₂ , a sample was prepared by impregnation with an epoxy resin.

FIG. 1 shows temperature characteristics of core loss at a measurement frequency of 50 kHz and a measured magnetic flux density of 0.1 T. As is clear from the characteristic diagram, the soft magnetic alloy powder in the present embodiment has a negative core loss slope at room temperature (around 20 to 30 ° C.) and a minimum loss temperature of at least 80 ° C. or more. It can be seen that in the comparative example, since the core loss has a positive slope at room temperature and the minimum loss temperature is at least 25 ° C. or less, thermal runaway may occur at a high temperature.

(Eighth Embodiment) Next, an eighth embodiment of the present invention will be described.

The Fe—Al—Si soft magnetic alloy powder in the present embodiment was produced by the water atomization method so as to have the final composition shown in (Table 7). This Fe-Al-
The Si-based soft magnetic alloy powder was classified by a sieve so as to have an average particle diameter of 50 μm, and 1.5 parts by weight of butyral resin as an insulating binder was added to 100 parts by weight of the metal magnetic powder and mixed. By the uniaxial press of the mixed powder,
A molded body having an E-shape and an I-shape was formed at a molding pressure of 10 ton / cm ² . Thereafter, 700 ° C. in N ₂
And then impregnated with an epoxy resin to prepare a sample. This sample was used for the DC / DC converter choke coil and PCC used in the notebook computer.
(Power-Coke-Coil) and frequency 200k
Hz. Table 7 shows the results of the temperature rise at that time.
Shown in

As is clear from (Table 7), 4 is obtained by weight.
When using 5% ≦ Al ≦ 8.5%, 7.5% ≦ Si ≦ 9.5%, and Fe-Al-Si soft magnetic alloy powder containing Fe as a main component, the temperature rise is increased by 30 ° C. The following can be suppressed.

[0057]

[Table 7]

[0058]

As is apparent from the above description, according to the present invention, it is possible to provide a composite magnetic material having low core loss, high magnetic permeability and excellent magnetic properties in a high frequency region.

[Brief description of the drawings]

FIG. 1 is a diagram showing temperature characteristics of core loss of the present invention in comparison with a conventional example.

FIG. 2 shows the maximum magnetic permeability μ of an Fe—Al—Si alloy.
characteristic diagram showing the dependence of m on Fe, Si and Al concentrations

FIG. 3 shows the F of the initial magnetic permeability μ _i in the central region of Sendust
Characteristic diagram showing e, Si and Al concentration dependency

Claims (10)

[Claims] 1. A ferromagnetic material in which the sign of the magnetostriction constant λ is positive at room temperature.
-A composite magnetic material comprising an Al-Si-based soft magnetic alloy powder, wherein a temperature coefficient of core loss at room temperature is negative. 2. The minimum temperature at which the core loss is minimized,
2. The composite magnetic body according to claim 1, wherein the temperature is 80 [deg.] C. or higher. 3. The composition of the soft magnetic alloy powder is 4.5% ≦ Al ≦ 8.5%, 7.5% ≦ Si ≦ 9.5% by weight.
2. The composite magnetic material according to claim 1, wherein the composite magnetic material comprises% and the balance of Fe. 4. The composite magnetic body according to claim 1, wherein the soft magnetic alloy powder is formed by a gas atomization method, a water atomization method, or a pulverization method after alloying by melting. 5. An average particle size of the soft magnetic alloy powder is 1 μm.
2. The composite magnetic body according to claim 1, wherein the thickness is at least 100 μm. 6. An alloy in which the sign of the magnetostriction constant λ is positive at room temperature.
-A method for producing a composite magnetic material, comprising mixing an Al-Si soft magnetic alloy powder with an electrically insulating binder, compression-molding the mixture, and then heat-treating the mixture at a temperature of 500 ° C to 900 ° C. 7. The composition of the soft magnetic alloy powder is 4.5% ≦ Al ≦ 8.5%, 7.5% ≦ Si ≦ 9.5% by weight.
7. The method for producing a composite magnetic material according to claim 6, wherein the composition is composed of% and the balance of Fe. 8. The composite magnetic body according to claim 6, wherein the electrically insulating binder is made of at least one of an epoxy resin, a phenol resin, a vinyl chloride resin, a butyral resin, and an organic silicone resin. Manufacturing method. 9. The composition has a weight percentage of 4.5% ≦ Al ≦ 8.5.
%, 7.5% ≦ Si ≦ 9.5%, the balance being Fe, the oxygen content is not less than 1000 ppm and not more than 8000 ppm, and the sign of the magnetostriction constant λ is positive at room temperature. Si-based soft magnetic alloy powder. 10. The Fe—Al—Si soft magnetic alloy powder according to claim 9, wherein the soft magnetic alloy powder is produced by a water atomization method or a pulverization method of a molten alloy.