JP2000235915A - High permeability oxide magnetic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high initial permeability characteristic and high impedance characteristic at the same time. SOLUTION: In a high permeability oxide magnetic material, main components are constituted of Fe2O3 52.0-53.0 mol%, ZnO 19.0-23.5 mol%, and residual is MnO. As the subcomponents, 0.005-0.025 wt.% of SiO2, CaO 0.02-0.07 wt.%, Bi2O3 0.01-0.03 wt.% and Ta2O5 0.01-0.09 wt.% are contained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide magnetic material suitable for a ferrite core material for a power transformer or a choke coil.

[0002]

2. Description of the Related Art In recent years, there has been remarkable technological innovation in miniaturization and high performance of electronic equipment, and accordingly, there has been a demand for higher performance of Mn-Zn ferrite used.

For example, high permeability and low loss are required. In particular, a ferrite core for a noise filter is required to have high magnetic permeability and impedance. Generally, the main component composition of the Mn—Zn-based ferrite having high magnetic permeability is 52.0 to 53.0 mol% Fe.
₂ O ₃ , 24.0 to 28.0 mol% MnO, balance ZnO
The composition is near, and those currently on the market are compositions in this range.

[0004] The Mn-Zn ferrite sometimes contains SiO ₂ , CaO, Bi ₂ O ₃ or the like as an auxiliary component. SiO ₂ and CaO reduce the eddy current loss by forming a high-resistance grain boundary layer, and in particular, the initial magnetic permeability (μ
It is added for the purpose of improving the frequency characteristics of i).

[0005] Bi ₂ O ₃ is added for the purpose of promoting grain growth, and is for obtaining a large crystal grain size necessary for obtaining a high initial magnetic permeability. When the initial permeability (μi) maintains a high value up to a high frequency, the peak value of the imaginary part (μ ″) appears on the high frequency side, thereby increasing the impedance (Z). In addition, it is necessary not only to examine the above composition to select an optimal composition, but also to make the crystal grain size relatively large and uniform.

[0006]

The above-mentioned conventional Mn-Z
The n-type ferrite has the following problems. That is,
Bi ₂ O ₃ is effective for promoting grain growth, but is also a factor for promoting abnormal grain generation. The abnormal grains increase the eddy current loss, reduce the specific resistance, and cause a significant reduction in impedance. Therefore, it has been difficult to simultaneously achieve high initial magnetic permeability and high impedance characteristics.

Accordingly, the present invention provides high initial permeability characteristics and
An object of the present invention is to provide a high-permeability oxide magnetic material having high impedance characteristics at the same time.

[0008]

[Means for Solving the Problems] The results of various studies
As a result, the main component composition of 52.0 to 53.0 mol% of Fe₂O
₃, 19.0 to 23.5 mol% ZnO, balance MnO
And 0.005 to 0.025 wt% of S as a sub-component.
iO₂, 0.02-0.07 wt% CaO, 0.01-
0.03 wt% Bi₂O₃, 0.01 to 0.09 wt%
Ta₂O₅Mn-Zn based ferrite containing
Has high initial permeability and high impedance characteristics
Was.

The product of the present invention has higher initial magnetic permeability, higher specific resistance and higher impedance than conventional Mn-Zn ferrite.

[0010] Bi₂O₃Has the effect of promoting grain growth.
, Ta₂O₅Has the effect of growing crystal grains uniformly.
You. Bi₂O₃Increases the crystal grain size and further increases Ta
₂O ₅By growing crystal grains uniformly,
4μ which suppresses normal grain growth and is said to have no domain wall
m, the frequency of fine particles less than
A high initial permeability can be obtained without reducing the dance.

The main component is 52.0-53.0 mol% of Fe.
₂ O ₃ , 19.0 to 23.5 mol% ZnO, balance Mn
The reason for choosing O is that when Fe ₂ O ₃ is 52.0 mol% or less, the impedance is reduced. Also,
If the content of Fe ₂ O ₃ is 53.0 mol% or more, a sufficient initial magnetic permeability cannot be obtained. In addition, ZnO is 1
If it is less than 9.0 mol%, a sufficient initial magnetic permeability cannot be obtained, and if it is more than 23.5 mol%, the Curie temperature (T
This is because c) decreases and is not practical.

The subcomponent is 0.005 to 0.025 wt% of S.
iO₂, 0.02-0.07 wt% CaO, 0.01-
0.03 wt% Bi₂O₃, 0.01 to 0.09 wt%
Ta ₂O₅The reason is that SiO₂0.005wt%
Or less, and high resistance when CaO is 0.02 wt% or less.
Cannot obtain high grain boundary layer and high impedance
That's why. SiO₂Is 0.025 wt% or more, and C
When aO is 0.07 wt% or more, sufficient initial magnetic permeability is obtained.
I can't get it. Bi₂O₃Is 0.01% by weight or less
, The effect of crystal grain growth was not obtained, and 0.03 wt% or more
, Then Ta₂O₅Suppresses abnormal grain growth
Eddy current loss increases due to the generation of abnormal grains,
This is to reduce resistance and impedance. Ta₂O
₅Is less than 0.01 wt%, the grain growth is uniform.
Effect is not sufficiently obtained, and is 0.09 wt% or more.
And solid solution as an impurity in the crystal grains, lowering the initial permeability
It is to make it.

That is, according to the present invention, the main components are 52.0 to 5
3.0 mol% of Fe ₂ O ₃ , 19.0 to 23.5 mol
% Of ZnO, with the balance being MnO, a high-permeability oxide magnetic material, wherein 0.005 to 0.025 wt%
SiO ₂ , 0.02 to 0.07 wt% CaO, 0.0
1～0.03Wt% of _Bi 2 _O 3, _0.01~0.09w
It is a high-permeability oxide magnetic material containing t% Ta ₂ O ₅ .

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to examples.

[0015]

EXAMPLES (Example 1) As the invention, 52.5 mol% of Fe ₂ O ₃ and 22.5 mol% of Z as main components were used as the main components.
nO, balance MnO, 0.015 wt% of S as a sub-component
0.03 wt% of Ca (O ₂ , CaO)
H) ₂ , 0.015 wt% Bi ₂ O ₃ , 0.03 wt%
Of Ta ₂ O ₅ was weighed and mixed using an attritor for 2 hours.

After mixing, the mixture was granulated with a spray drier. Thereafter, each mixed powder was pre-fired in an atmosphere at 850 ° C. for 2 hours. The obtained powder was ground using an attritor. After crushing, granulate with a spray drier, 25mm
It was pressed into a toroidal shape of φ-15 mmφ-12 mm, and fired at a firing temperature of 1350 ° C. and a holding time of 2 hours.

As a conventional product, the main component composition is 52.5.
mol% Fe ₂ O ₃ , 22.5 mol% ZnO, balance MnO, 0.015 wt% SiO ₂ as a subcomponent,
0.03 wt% CaO, 0.015 wt% Bi ₂ O ₃
Was produced by the same process.

Tables 1 and 2 show the specific resistance of the invention product and the conventional product,
Curie temperature (T _c ), 10 kHz and 100 kHz
Shows the initial permeability (μ) and the maximum value (Z _max ) of the impedance when the number of windings is 10 Turn.

[0019]

[Table 1]

[0020]

[Table 2]

It can be seen that the invention product has higher μ, _Zmax and specific resistance than the conventional product.

FIG. 1 shows the frequency characteristics of the initial magnetic permeability of the invention product and the conventional product. From FIG. 1, it can be seen that the invention product maintains a high initial magnetic permeability up to high frequencies.

(Example 2) As an invention product, 52.0 to 53.0 mol% of Fe ₂ O ₃ , 19.0% as a main component composition,
２３23.5 mol% of ZnO, balance MnO, and 0.015 wt% of SiO ₂ and CaO as subcomponents in terms of 0.0.
3 wt% Ca (OH) ₂ , 0.015 wt% Bi ₂
O ₃ , 0.03 wt% of Ta ₂ O ₅ was weighed and mixed using an attritor for 2 hours. After mixing, the mixture was granulated with a spray dryer.

Thereafter, each mixed powder was pre-fired in an atmosphere at 850 ° C. for 2 hours. The obtained powder was ground using an attritor. After crushing, granulate with a spray drier,
It was pressed to a toroidal shape of 5 mmφ-15 mmφ-12 mm and fired at a firing temperature of 1350 ° C. and a holding time of 2 hours.

As a comparative product, the main component composition was 51.0.
mol% Fe ₂ O ₃ , 20.5 mol% ZnO, balance MnO, 0.015 wt% SiO ₂ as a subcomponent,
0.03 wt% CaO, 0.015 wt% Bi
₂ O ₃ , 0.03 wt% of Ta ₂ O ₅ (comparative product 1), main component composition 54.0 mol% of Fe ₂ O ₃ , 20.5 mol
% ZnO, balance MnO, 0.015 wt% as a sub-component
% SiO ₂ , 0.03 wt% CaO, 0.015 wt%
% Bi ₂ O ₃ , 0.03 wt% Ta ₂ O ₅ (comparative product 2), 52.2 mol% of main component composition Fe ₂ O ₃ , 18.
0 mol% ZnO, balance MnO, 0.0 as a subcomponent
15 wt% SiO ₂ , 0.03 wt% CaO, 0.0
15 wt% Bi ₂ O ₃ , 0.03 wt% Ta ₂ O ₅
(Comparative product 3), Fe ₂ O having a main component composition of 52.2 mol%
₃ , 25.0 mol% of ZnO, balance MnO, 0.015 wt% of SiO ₂ and 0.03 wt% of Ca as subcomponents
O, 0.015 wt% Bi ₂ O ₃ , 0.03 wt% T
Mn-Zn ferrite containing a ₂ O ₅ (Comparative Product 4) was also prepared by the same process.

Tables 3 and 4 show the specific resistance of the invention product and the comparison product,
Curie temperature (T_c), Initial permeability at 100 kHz
(Μ), the maximum value of the impedance when the number of turns is 10 Turn
(Z _max).

[0027]

[Table 3]

[0028]

[Table 4]

It can be seen that the invention of 52.0 to 53.0 mol% Fe ₂ O ₃ has high μ, Z and specific resistance. It can be seen that the invention product containing 19.0 to 23.5 mol% of ZnO has high μ, Z, and _Tc .

(Example 3) As an invention product, the main component composition and
And 52.2 mol% of Fe₂O₃, 22.0 mol%
ZnO, balance MnO, 0.005 to 0.02 as accessory components
5wt% SiO ₂0.02 to 0.0 in terms of CaO
7 wt% Ca (OH)₂, 0.015 wt% Bi₂
O₃, 0.03 wt% Ta₂O₅Weigh and try
Mix for 2 hours using a mixer. After mixing, spray
Granulated in the year.

Thereafter, each mixed powder was pre-fired in an atmosphere at 850 ° C. for 2 hours. The obtained powder was ground using an attritor. After crushing, granulate with a spray drier,
It was pressed to a toroidal shape of 5 mmφ-15 mmφ-12 mm and fired at a firing temperature of 1350 ° C. and a holding time of 2 hours.

As a comparative product, the main component composition was 52.2.
mol% Fe₂O₃, 22.0 mol% ZnO, residual
Part MnO, 0.03 wt% CaO as a sub-component, 0.0
15wt% Bi₂O₃, 0.03 wt% Ta₂O₅
(Comparative product 5), Fe having a main component composition of 52.2 mol%₂O
₃, 22.0 mol% of ZnO, balance MnO, and subcomponents
0.03 wt% SiO₂0.03 wt% Ca
O, 0.015 wt% Bi ₂O₃, 0.03 wt% T
a₂O₅(Comparative product 6), 52.2 mol% Fe
₂O ₃, 22.0 mol% ZnO, balance MnO, by-product
0.015wt% SiO₂, 0.01 wt%
CaO, 0.015 wt% Bi₂O₃, 0.03wt%
Ta₂O₅(Comparative product 7), 52.2 mol% Fe₂
O₃, 22.0 mol% ZnO, balance MnO, subcomponent
0.015 wt% SiO₂, 0.08 wt% C
aO, 0.015 wt% Bi₂O₃, 0.03 wt%
Ta₂O₅Mn-Zn ferrite containing (Comparative product 8)
The same procedure was used to make the same.

Tables 5 and 6 show the specific resistance of the invention product and the comparison product.
Anti-Curie temperature (T_c), First transmission at 100 kHz
Magnetic susceptibility (μ), the maximum impedance of 10 Turns
Large value (Z _max).

[0034]

[Table 5]

[0035]

[Table 6]

0.005 to 0.025 wt% of SiO ₂ ,
The invention product in which 0.02 to 0.07 wt% of CaO is used is μ,
It can be seen that Z and the specific resistance are high.

Example 4 Inventive products were converted to 52.2 mol% of Fe ₂ O ₃ , 22.0 mol% of ZnO, balance MnO, and 0.015 wt% of SiO ₂ and CaO as auxiliary components as main components. 0.03 wt% of Ca (O
_H) 2, 0.005~0.035wt% of _Bi 2 _O 3,
0.005 to 0.01 wt% of Ta ₂ O ₅ was weighed and mixed for 2 hours using an attritor. After mixing, the mixture was granulated with a spray dryer.

Thereafter, each mixed powder was pre-fired in the air at 850 ° C. for 2 hours. The obtained powder was ground using an attritor. After crushing, granulate with a spray drier,
It was pressed to a toroidal shape of 5 mmφ-15 mmφ-12 mm and fired at a firing temperature of 1350 ° C. and a holding time of 2 hours.

As a comparative product, the main component composition 52.2
mol% Fe ₂ O ₃ , 22.0 mol% ZnO, balance MnO, 0.015 wt% SiO ₂ as a subcomponent,
0.03 wt% CaO, 0.005 wt% Bi
₂ O ₃ , 0.03 wt% of Ta ₂ O ₅ (comparative product 9), main component composition 52.2 mol% of Fe ₂ O ₃ , 22.0 mol
% ZnO, balance MnO, 0.015 wt% as a sub-component
% SiO ₂ , 0.03 wt% CaO, 0.035 wt%
% Bi ₂ O ₃ , 0.03 wt% Ta ₂ O ₅ (comparative product 10), 52.2 mol% Fe ₂ O ₃ , 22.0 mol
% ZnO, balance MnO, 0.015 wt% as a sub-component
% SiO ₂ , 0.03 wt% CaO, 0.015 wt%
% Bi ₂ O ₃ , 0.005 wt% Ta ₂ O ₅ (comparative product 11), 52.2 mol% Fe ₂ O ₃ , 22.0 mo
1% ZnO, balance MnO, 0.015 w
t% SiO ₂ , 0.03 wt% CaO, 0.015 w
t% of _Bi 2 _O 3, 0.1wt% of _Ta 2 _{O 5} Mn-Zn ferrite containing (comparative product 12) was also prepared by the same process.

Tables 7 and 8 show the specific resistance of the comparative product and the invention product,
Curie temperature (T_c), Initial permeability at 100 kHz
(Μ), the maximum value of the impedance when the number of turns is 10 Turn
(Z _max).

[0041]

[Table 7]

[0042]

[Table 8]

0.01-0.03 wt% Bi ₂ O ₃ ,
The invention product in which 0.01 to 0.09 wt% of Ta ₂ O ₅ is used,
It can be seen that μ, Z and the specific resistance are high.

As described above, the main component composition is 5
2.0～53.0Mol% of _Fe 2 _O 3, _19.0~23.
5 mol% of ZnO, balance MnO, 0.005 to 0.025 wt% of SiO ₂ , 0.02 to
0.07 wt% CaO, 0.01 to 0.03 wt% B
i ₂ O _3, that the Mn-Zn ferrite containing of _Ta 2 _{O 5 which has} a 0.01~0.09wt%, high-permeability magnetic oxide that achieves high initial permeability and impedance characteristics at the same time is obtained Was found.

By adding Ta ₂ O ₅ , uniform grain growth is achieved, abnormal grain growth is suppressed, and the frequency of fine grains is reduced. Further, by adding Bi ₂ O ₃ , grain growth is promoted. Without causing abnormal grains and with specific resistance,
A high initial permeability was obtained without reducing the impedance.

[0046]

As described above, according to the present invention, it is possible to provide a high-permeability oxide magnetic material which simultaneously realizes a high initial permeability characteristic and a high impedance characteristic in Mn-Zn based ferrite.

[Brief description of the drawings]

FIG. 1 is a diagram showing frequency characteristics of a high-permeability oxide magnetic material according to an embodiment of the present invention in comparison with a conventional product.

Claims (1)

[Claims] 1. The method according to claim 1, wherein the main component is 52.0 to 53.0 mol% of F.
e ₂ O ₃ , a high-permeability oxide magnetic material containing 19.0 to 23.5 mol% of ZnO and the balance being MnO, and 0.005 to 0.025 wt% of SiO ₂ as a subcomponent, 0.0
2 to 0.07 wt% CaO, 0.01 to 0.03 wt%
High magnetic permeability oxide magnetic material, characterized in that it contains Bi ₂ O ₃ and 0.01 to 0.09 wt% of Ta ₂ O ₅ .