JP2003151812A - High-permeability oxide magnetic material and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-permeability oxide magnetic material having high impedance together with high permeability. SOLUTION: This high-permeability oxide magnetic material is composed of Mn-Zn ferrite powder having a mean crystal grain diameter of 36 μm, coated with an Ni-Zn ferrite layer having a thickness of 0.5 μm, and containing 53.0 mol% Fe2 O3 , 22.5 mol% ZnO, and a remainder (24.5 mol%) MnO as main components. The magnetic material is obtained by hot compression-molding composite powder manufactured by conducting the ultrasonic wave-excited ferrite plating method under a temperature condition of 400 deg.C. The magnetic material has well-balanced high permeability μ and impedance Z to frequencies (kHz) among the conventional oxide magnetic materials obtained by separately adding accessory constituents to nearly the same main constituents and baking the constituents at high temperatures.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-permeability oxide magnetic material suitable for use as a ferrite core material for a noise filter, having a high magnetic permeability and a high impedance characteristic, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, technological innovations for miniaturization and high performance of electronic devices have been remarkable, and accordingly, Mn-Zn ferrite used as a magnetic material has high performance (high magnetic permeability and low loss). Is required. Especially when applied as a ferrite core material for a noise filter, Mn-Zn
The system ferrite is required to have high initial permeability and high impedance.

Therefore, in order to achieve high initial permeability in Mn-Zn ferrite, it is essential to improve the magnetocrystalline anisotropy constant and the crystal structure,
Further, considering that the operating environment temperature is near room temperature, a material having a main component composition that has the smallest magnetocrystalline anisotropy constant at room temperature is used. Specifically, the main component composition is 52.0-
52.5 Fe ₂ O ₃ in (mol%), 24.0~28.
MnO of 0 (mol%), Mn-Zn near the balance ZnO
The ferrite-based ferrite materials can be exemplified, but the main component composition of Mn—Zn-based ferrite materials currently on the market is within this range. Further, since the initial magnetic permeability depends on the crystal structure, it is desired that the crystal grain size in the powder of the Mn-Zn ferrite material is as large as possible. Specifically, the well-known powder powder metallurgy method is applied. A method of increasing the crystal structure by adding a grain growth promoting additive such as Bi ₂ O ₃ has been adopted.

On the other hand, in the case of Mn-Zn ferrite, it is indispensable to increase the specific resistance value in order to achieve high impedance. Specifically, eddy current loss which is a loss component of ferrite is required. To reduce
SiO ₂ , CaO for Mn-Zn ferrite powder
A method of forming a grain boundary layer having a high specific resistance is adopted by adding a component for generating a grain boundary layer such as. That is,
The eddy current loss increases as the frequency increases, and the initial permeability decreases due to the effect in the high frequency region, so an effective means to prevent this is to increase the specific resistance of the magnetic material,
As a result, the frequency characteristic of the initial permeability in the high frequency range becomes good, and in such a case, the impedance becomes large.

[0005]

In the case of Mn-Zn type ferrite as the above-mentioned magnetic material, the powder powder metallurgy method is applied for the purpose of increasing the crystal grain size of the powder in order to obtain a high initial magnetic permeability. B for Mn-Zn ferrite powder
Although grain growth promoting additives such as i ₂ O ₃ are added,
Addition of ₂ O ₃ also causes a disadvantage that it promotes abnormal grain growth, and this abnormal grain increases eddy current loss and reduces specific resistance, thereby significantly reducing impedance. Therefore, if the conventional powder powder metallurgy method is applied, it is difficult to produce an oxide magnetic material having a high initial magnetic permeability and a high impedance at the same time.

[0006] In the Mn-Zn ferrite, although the addition of SiO _2, CaO or the like in order to form a grain boundary layer of high resistivity against powder in order to obtain a high impedance, SiO _2, CaO The addition of such a compound also has the effect of suppressing grain growth. Therefore, if a conventional powder powder metallurgy method is applied, a grain boundary layer having a large crystal grain size and high resistivity can be obtained. There is a problem that is difficult.

In short, in the case of the conventional Mn-Zn-based ferrite, although the individual factors and measures for achieving high magnetic permeability and high impedance are known, respectively, a technique for achieving both purposes at the same time. Since it is not known, it is the current situation that the powder powder metallurgy method must be applied to design the material so that the balance between the magnetic permeability and the impedance is optimized, resulting in high magnetic permeability. There is a problem in that a high-permeability oxide magnetic material having high impedance characteristics cannot be obtained.

The present invention has been made to solve such a problem, and its technical problem is to provide a high magnetic permeability oxide magnetic material having high magnetic permeability and high impedance characteristics, and a method for manufacturing the same. To provide.

[0009]

According to the present invention, a high-permeability oxide magnetic material comprising a composite powder in which the surface of Mn-Zn ferrite powder as a base material is coated with a Ni-Zn ferrite layer can be obtained.

Further, according to the present invention, in the above high-permeability oxide magnetic material, the Mn-Zn ferrite powder is Fe whose main component composition is 51.0 to 55.0 (mol%).
_A high-permeability oxide magnetic material composed of ₂ O ₃ , 15.0 to 25.0 (mol%) ZnO, and the balance MnO is obtained.

Further, according to the present invention, in any of the above high permeability magnetic oxide materials, a high permeability oxide magnetic material having an average particle diameter of Mn-Zn ferrite powder of 10 μm or more can be obtained.

In addition, according to the present invention, in any one of the above-mentioned high magnetic permeability oxide magnetic materials, the composite powder is a high magnetic permeability oxide magnetic material produced by applying an ultrasonic excitation ferrite plating method. Furthermore, a high-permeability oxide magnetic material having a specific resistance of 50 Ωcm or more can be obtained.

On the other hand, according to the present invention, the base material Mn-
A powder dispersion step of dispersing Zn ferrite powder in an aqueous solution; a ferrite coating step of coating the surface of Mn-Zn ferrite dispersed in the aqueous solution with a Ni-Zn ferrite layer by ferrite plating to obtain a composite powder; And a compression molding step of obtaining a high magnetic permeability oxide magnetic material by hot compression molding under the temperature condition of 300 to 500 (° C.).

On the other hand, according to the present invention, in the above-mentioned method for producing a high-permeability oxide magnetic material, in the powder dispersion step, M
The main component composition of the n-Zn ferrite powder is 51.0.
Fe ₂ O ₃ of ~55.0 (mol%), 15.0~2
It is composed of 5.0 (mol%) ZnO and the balance MnO and has an average particle size of 10 μm or more. In the ferrite coating step, a composite powder is produced by ultrasonic excitation ferrite plating, and in the compression molding step, It is possible to obtain a method for producing a high-permeability oxide magnetic material in which the high-permeability oxide magnetic material has a specific resistance of 50 Ωcm or more.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

First, a technical outline of the high-permeability oxide magnetic material of the present invention and the manufacturing method thereof will be described.
As a result of various studies, the present inventors have found that the average particle size is 10
The composite powder made of Mn-Zn ferrite powder having a powder surface of μm or more coated with a Ni-Zn ferrite layer is heated at a temperature condition of 300 to 500 (° C). It was found that the high permeability oxide magnetic material having high permeability and high impedance characteristics can be obtained by the inter-compression molding. However, here, Fe ₂ having a main component composition of Mn—Zn ferrite as a base material of 51.0 to 55.0 (mol%)
O ₃ , 15.0 to 25.0 (mol%) ZnO, and the balance MnO, and the specific resistance after hot compression molding is 50 Ωc.
It is necessary to make it m or more.

That is, in the high-permeability oxide magnetic material of the present invention, the surface of the Mn-Zn ferrite powder as the base material is Ni.
A composite powder coated with a -Zn ferrite layer, the main component composition of which is 51.0 Mn-Zn ferrite powder.
Fe ₂ O ₃ of ~55.0 (mol%), 15.0~2
Assuming that the composite powder is made of 5.0 (mol%) ZnO and the balance MnO and has an average particle size of 10 μm or more, and the composite powder is produced by applying the ultrasonic excitation ferrite plating method, the specific resistance is It is 50 Ωcm or more.

In the case of producing such a high-permeability oxide magnetic material, a powder dispersion step of dispersing Mn-Zn ferrite powder as a base material in an aqueous solution and a surface of the Mn-Zn ferrite dispersed in the aqueous solution. And a ferrite coating step of coating the same with a Ni-Zn ferrite layer by ferrite plating to obtain a composite powder, and performing hot compression molding of the composite powder under a temperature condition of 300 to 500 (° C) to obtain a high-permeability oxide magnetic material. The resulting compression molding step may be performed. However, in the powder dispersion step, as Mn—Zn ferrite powder, Fe ₂ O ₃ having a main component composition of 51.0 to 55.0 (mol%),
15.0 to 25.0 (mol%) ZnO, balance MnO
And an average particle diameter of 10 μm or more is used. In the ferrite coating step, a composite powder is produced by an ultrasonic excitation ferrite plating method. In the compression molding step, a high-permeability oxide magnetic material has a specific resistance of 50 Ωcm or more. Shall be obtained.

By carrying out the method for producing such a high-permeability oxide magnetic material, a high magnetic permeability and a high impedance characteristic which cannot be realized when the conventional powder powder metallurgy method is applied are combined. Since a magnetic permeability oxide magnetic material can be obtained, it is suitable as a ferrite core material for a noise filter.

In the high-permeability oxide magnetic material obtained as the composite magnetic material according to the present invention, Mn-Zn ferrite powder in which Ni-Zn ferrite is uniformly and firmly coated is compression-molded to obtain Mn-Zn ferrite particles. Since Ni-Zn ferrite having a high specific resistance exists between them, it plays a role of enhancing the insulating property. Therefore, the bulk resistivity is 5
Although it is set to 0 Ωcm or more, the bulk resistivity can be controlled in any way by changing the amount of plating on the Mn-Zn ferrite powder. When the conventional powder powder metallurgy method is applied, the grain boundary layer of the glass layer is formed by adding the additives and precipitating in the holding and cooling process of firing, but it is difficult to change the thickness. On the other hand, according to the method here, the bulk resistivity can be controlled very easily by changing the plating amount. Moreover,
Since this ferrite plating layer is a magnetic layer, it plays a role of magnetically coupling the Mn-Zn ferrite particles of the base material to each other, and thereby has a higher Curie temperature Tc than conventional Mn-Zn ferrite. Becomes In the case of Mn-Zn ferrite as the base material here, since a grain boundary layer that precipitates in the holding and cooling stage of firing is not generated and it is not necessary to add a trace amount additive that suppresses grain growth, a trace amount additive is added. By not adding it, a crystal grain size distribution without defects such as abnormal grain growth can be obtained.

The manufacturing process of the high-permeability oxide magnetic material of the present invention requires a process of hot compression molding the composite powder under a temperature condition of 300 to 500 (° C.). Generally, Mn-
Zn ferrite requires a firing process and is usually 1200 to
Although it is fired under a temperature condition of 1400 (° C.), the main reason for firing at such a high temperature is that the pulverized powder has a size of the order of μm, and firing to a certain degree requires high temperature firing. Secondly, it is necessary that a certain degree of firing temperature is required for melting SiO ₂ and CaO, which are the materials for forming the grain boundary layer. On the other hand, the plated Ni-Zn ferrite powder in the composite magnetic material of the present invention is on the order of nm, and can be sufficiently densified at low temperature, and the plating layer becomes a grain boundary layer and becomes a grain boundary layer. Since it is not necessary to precipitate the components, calcination at high temperature is not necessary. As described above, if it is not necessary to perform firing at a high temperature, Mn-Zn ferrite as a base material and Ni- as a plated material
There is no compositional mixture between Zn ferrites, and thus an oxide magnetic material having high magnetic permeability can be obtained.

The manufacturing process of the high permeability oxide magnetic material of the present invention
Main component of Mn-Zn ferrite powder of the base material
Fe having a composition of 51.0 to 55.0 (mol%)₂O₃，
15.0 to 25.0 (mol%) ZnO, balance MnO
The reason is defined as ₂O₃Is 51.0 mol%
Below, if ZnO is 15 mol% or less, the crystal magnetic anomaly is
The orientation constant becomes high, leading to a decrease in magnetic permeability.₂O₃
Is 55 mol% or more, Fe²⁺Is increasing the specific resistance
Eddy current loss increases as
The number characteristic is deteriorated, and ZnO is 25 mol% or less.
And the Curie temperature Tc becomes low, the noise filter material
Avoid these difficulties as
This is because Also, the base material Mn-Zn ferrite powder
The reason why the average particle size of 10 μm or more is that the average particle size is 1
This is because if it is 0 μm or less, the magnetic permeability becomes small. Change
The reason why the bulk resistivity is 50 Ωcm or more is
If the resistance is 50 Ωcm or less, eddy current loss may deteriorate.
This is to deteriorate the frequency characteristic of magnetic permeability. In addition
Heat the composite powder under the temperature condition of 300 to 500 (° C).
The reason for performing inter-stage compression molding is that the temperature condition is 300 ° C or less.
And the densification between the Ni-Zn ferrite which is the plating powder
This is because the magnetic permeability does not progress and becomes smaller, and the temperature is 500 ° C or higher.
Mn-Zn ferrite powder and plating powder of the base material
Of Ni-Zn ferrite powder of
Is to induce.

The following will specifically describe the high-permeability oxide magnetic material of the present invention with reference to some embodiments, together with the manufacturing steps thereof.

(First Embodiment) In the first embodiment, first, as a base material Mn-Zn ferrite powder, each has an average crystal grain size of more than 30 μm and a main component composition of 50.5. ~55.5 Fe ₂ O ₃ in (mol%), 1
4.0 to 26.0 (mol%) ZnO, balance (ba
l) Weighed and mixed to obtain MnO at 1200 ° C
Of several different types of base metal powders were prepared by pre-firing in a nitrogen atmosphere.

Next, in a powder dispersion step, Mn-Zn ferrite powder particles, which are the base material powders, are heated to a water temperature of 80 ° C.
After dispersion in an aqueous solution of, as a ferrite coating step,
While keeping the temperature of the dispersion constant, FeCl ₂ (12 g /
l), NiCl ₂ (4 g / l), ZnCl ₂ (0.5 g
/ L) each Mn-dispersed in the aqueous solution using the reaction solution
The surface of Zn ferrite is Ni-plated with ferrite.
Several different kinds of composite powders were obtained by performing ferrite plating so as to cover with a Zn ferrite layer.
However, as a ferrite plating method here, an ultrasonic excitation ferrite plating method is applied, and an oxidizing agent such as nitrite NaNO ₂ is gradually added while vigorously moving the liquid by applying ultrasonic waves with an ultrasonic horn. The process was carried out by oxidization, and the pH was adjusted with NH ₄ OH or the like by a pH controller to immerse the Mn-Zn ferrite powder as a base material in a substantially neutral reaction solution. In this way, the Mn-Zn ferrite powder particles of the base material are not attacked by the reaction liquid for ferrite plating, and a coating layer of Ni-Zn ferrite plating having a thickness of 0.5 [mu] m is formed on the surface of the particles to form several different layers. A kind of composite powder was obtained.

Further, as a compression molding step, each of the obtained composite powders is hot compression molded under a temperature condition of 400 ° C. to obtain a high permeability oxide magnetic material according to some invention products and comparative products. Obtained. At the same time, as a conventional product, the base material Mn
-Zn ferrite powder having an average crystal grain size of 20 μm and a main component composition of 52.5 mol% Fe ₂ O ₃ ,
22.5 mol% ZnO and the balance MnO,
As an accessory component 0.015 wt% SiO ₂ , 0.03 w
t% CaO and 0.015 wt% Bi ₂ O ₃ are weighed and mixed so as to be pre-baked, crushed and granulated, and then fired in a reducing atmosphere at a temperature condition of 1350 ° C. Thus, an oxide magnetic material was obtained.

Table 1 shows various invention products 1 to 13 and comparative products 1 to 4 and conventional products when the main component composition and the average crystal grain size of the Mn-Zn ferrite powder are changed in this way. Bulk resistivity (Ωcm), Curie temperature Tc (° C), average crystal grain size (μm), magnetic permeability μi at 100 kHz, maximum impedance Zmax
It is shown by comparing (Ω).

[0028]

[Table 1]

From Table 1, the main component composition of the Mn-Zn ferrite powder of the base material is 51.0 to 55.0 (mol%) of Fe ₂ O ₃ and 15.0 to 25.0 (mol%). Zn
The invention products 1 to 13 in which the ranges of O and the balance MnO are higher than those of the other comparison products 1 to 4 and the conventional product in a well-balanced high value in both the magnetic permeability μi and the maximum value Zmax of the impedance. It is understood that there is.

FIG. 1 shows the characteristics of the magnetic permeability μ and the impedance Z with respect to the frequency (kHz) of the conventional product and the invention product 4 here. From FIG. 1, the invention product 4
In the case of, it can be seen that the values of magnetic permeability and impedance are higher in the entire frequency range than in the conventional product.

(Second Embodiment) In the second embodiment, first, as the base material Mn-Zn ferrite powder, each has an average crystal grain size of 33 μm and a main component composition of 52.2 mol%. Fe ₂ O ₃ , 22.5 mol% Z
nO and balance MnO so that 12
A base material powder was prepared and prepared by pre-baking in a nitrogen atmosphere at 00 ° C.

Next, a powder dispersion step and a ferrite coating step were carried out in the same procedure as in the first embodiment to obtain a composite powder. However, here, the Mn-Zn ferrite powder particles of the base material were not attacked by the reaction liquid of the ferrite plating, and the surface thereof had a thickness of Ni- of 10 nm to 2 μm.
A coating layer of Zn ferrite plating was formed to obtain several types of composite powders.

Further, in this case, as the compression molding step, the obtained composite powders are mixed with each other in the same manner as in the case of the first embodiment.
By hot compression molding under a temperature condition of 0 ° C., high magnetic permeability oxide magnetic materials according to some invention products and comparative products were obtained. At the same time, an oxide magnetic material similar to that in the first embodiment was obtained as a conventional product.

Table 2 shows bulk ratios of various invention products 14 to 16 and comparative products 5 and conventional products when the thickness of Ni-Zn ferrite plating (thickness of plating layer) is changed in this way. Resistance (Ωcm), Curie temperature Tc
(° C.), average crystal grain size (μm), magnetic permeability μi at 100 kHz, and maximum impedance value Zmax (Ω) are shown for comparison.

[0035]

[Table 2]

From Table 2, the bulk resistivity is 50 Ωcm.
In the case of the invention products 14 to 16 having the above-mentioned plating layer thickness, the magnetic permeability μi is higher than that of the other comparative products 5 and conventional products.
It can be seen that a high value with good balance is obtained in both the maximum impedance value Zmax and the maximum impedance value Zmax.

(Third Embodiment) In the third embodiment, first, as the base material Mn-Zn ferrite powder, each has an average crystal grain size of 10 μm or more and a main component composition of 52.2 mol. % Fe ₂ O ₃ , 22.5 mol%
ZnO and the remaining MnO were weighed and mixed, and pre-baked in a nitrogen atmosphere of 600 to 1300 (° C.) to prepare several different types of base material powder.

Next, the powder dispersion step and the ferrite coating step were carried out in the same procedure as in the case of the first embodiment to obtain some different kinds of composite powders. However, also here, the Mn-Zn ferrite powder particles of the base material are not attacked by the reaction liquid of the ferrite plating, and the surface thereof is 0.5.
A coating layer of Ni—Zn ferrite plating having a thickness of μm was formed to obtain several types of composite powders.

Further, here, as a compression molding step, the obtained composite powders are mixed with each other in the same manner as in the case of the first embodiment.
By hot compression molding under a temperature condition of 0 ° C., high magnetic permeability oxide magnetic materials according to some invention products and comparative products were obtained. At the same time, an oxide magnetic material similar to that in the first embodiment was obtained as a conventional product.

Table 3 shows Mn- which is the base material in this way.
The bulk specific resistance (Ωcm), the Curie temperature Tc (° C), and the invention products 17 to 23 and the comparative product 6 and the conventional product when the average crystal grain size and the pre-calcination temperature of the Zn ferrite powder were changed, Average crystal grain size (μm), magnetic permeability μi at 100 kHz, maximum value Zmax of impedance
It is shown by comparing (Ω).

[0041]

[Table 3]

From Table 3, it can be seen that the Mn-Zn ferrite powder as the base material has an average crystal grain size of 10 μm or more and a pre-firing temperature of 700 ° C.
It can be seen that in the case of the invention products 17 to 23, high values with good balance were obtained in both the magnetic permeability μi and the maximum value Zmax of the impedance, as compared with the case of the other comparative product 6 and the conventional product.

(Fourth Embodiment) In the fourth embodiment, as the Mn-Zn ferrite powder of the base material, Fe ₂ O ₃ having a main component composition of 52.2 mol% and 22.5 mol% is used.
ZnO and the balance MnO were mixed and weighed and mixed, and pre-baked in a nitrogen atmosphere at 900 ° C. to prepare a base material powder.

Next, the powder dispersion step and the ferrite coating step were carried out in the same procedure as in the case of the first embodiment to obtain a composite powder of the same type. However, the Mn-
The Zn ferrite powder particles were not attacked by the reaction liquid of the ferrite plating, and the surface of the Zn ferrite powder had a thickness of 0.5 μm.
A coating layer of i-Zn ferrite plating was formed to obtain a composite powder of the same type.

Further, here, in the compression molding step, the obtained composite powder is different from the case of the first embodiment in that
By hot compression molding under temperature conditions changed in the range of 00 to 600 (° C.), high magnetic permeability oxide magnetic materials according to some invention products and comparative products were obtained. At the same time, an oxide magnetic material similar to that in the first embodiment was obtained as a conventional product.

Table 4 shows bulk ratios of various invention products 24 to 26 and comparative products 7 and 8 and conventional products when the temperature conditions during hot compression molding of the composite powder are changed in this way. Resistance (Ωcm), Curie temperature Tc
(° C.), average crystal grain size (μm), magnetic permeability μi at 100 kHz, and maximum impedance value Zmax (Ω) are shown for comparison.

[0047]

[Table 4]

From Table 4, the temperature during hot compression molding is 30
Invention products 24 to 26 changed in the range of 0 to 500 (° C)
It is understood that in the case of, in comparison with the cases of the other comparative products 7 and 8 and the conventional product, high values are obtained in good balance in both the magnetic permeability μi and the maximum value Zmax of the impedance.

[0049]

As described above, according to the present invention, Mn-Zn ferrite powder having an average particle size of 10 μm or more and a powder surface coated with a Ni-Zn ferrite layer is used, and ultrasonic excitation ferrite plating is performed. By subjecting the composite powder produced by applying the method to hot compression molding under temperature conditions of 300 to 500 (° C.), a high magnetic permeability oxide magnetic material having high magnetic permeability and high impedance characteristics can be obtained. Therefore, if this high-permeability oxide magnetic material is applied to a ferrite core material for a noise filter, it becomes much more suitable than the conventional one.

[Brief description of drawings]

FIG. 1 shows characteristics of magnetic permeability and impedance with respect to frequency in a conventional product and an invention product 4 described in the first embodiment of the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor ▲ Kichi ▼ Sakae Taku ▲ Kichi ▼             6-7-1, Koriyama, Taihaku-ku, Sendai City, Miyagi Prefecture             Tokin Co., Ltd. F term (reference) 5E041 AB02 AB19 BC01 BC08 CA01                       HB14 NN05 NN06 NN14 NN17

Claims (7)

[Claims] 1. A high-permeability oxide magnetic material comprising a composite powder in which the surface of a Mn—Zn ferrite powder as a base material is coated with a Ni—Zn ferrite layer. 2. The high-permeability oxide magnetic material according to claim 1.
In the above, the Mn-Zn ferrite powder is a main component group.
Fe with a composition of 51.0 to 55.0 (mol%) ₂O₃, 1
5.0 to 25.0 (mol%) ZnO, balance MnO
A high-permeability oxide magnetic material comprising: 3. The high-permeability oxide magnetic material according to claim 1, wherein the Mn-Zn ferrite powder has an average particle size of 10 μm or more. 4. The high-permeability oxide magnetic material according to claim 1, wherein the composite powder is produced by applying an ultrasonic excitation ferrite plating method. High permeability oxide magnetic material. 5. The high-permeability oxide magnetic material according to claim 1, wherein the high-permeability oxide magnetic material has a specific resistance of 50 Ωcm or more. 6. A powder dispersion step of dispersing Mn—Zn ferrite powder as a base material in an aqueous solution, and a surface of the Mn—Zn ferrite dispersed in the aqueous solution is coated with a Ni—Zn ferrite layer by ferrite plating. And a ferrite coating step of obtaining a composite powder by
And a compression molding step of obtaining a high-permeability oxide magnetic material by hot compression molding under a temperature condition of 500 to 500 (° C.). 7. The method for producing a high-permeability oxide magnetic material according to claim 6, wherein the Mn is used in the powder dispersing step.
As the Zn ferrite powder, the main component composition is 51.0 to
55.0 Fe ₂ O ₃ in (mol%), 15.0~25.
It consists of 0 (mol%) ZnO and the balance MnO,
An average particle size of 10 μm or more is used, in the ferrite coating step, the composite powder is produced by an ultrasonic excitation ferrite plating method, and in the compression molding step, the high magnetic permeability oxide magnetic material has a specific resistance of 50 Ωcm or more. And a method for producing a high-permeability oxide magnetic material.