JP2003217920A - MANUFACTURING METHOD OF Mn-Zn FERRITE MATERIAL - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing of an Mn-Zn ferrite material having low core loss as compared with that of the conventional. <P>SOLUTION: In the Mn-Zn based ferrite material, which contains 50.0-56.0 mol% Fe<SB>2</SB>O<SB>3</SB>, 5-20 mol% Zn and 30-45 mol% Mn as the main components, and has 0.03-0.1 wt.% CaCO<SB>3</SB>, 0.001-0.05 wt.% SiO<SB>2</SB>, 0.2-0.4 wt.% TiO<SB>2</SB>, 0.03-0.1 wt.% Co<SB>3</SB>O<SB>4</SB>and 0.01-0.05 wt.% ZrO<SB>2</SB>as secondary components, at least the average particle diameter of SiO<SB>2</SB>, TiO<SB>2</SB>, Co<SB>3</SB>O<SB>4</SB>and ZrO<SB>2</SB>is 100 nm or smaller, preferably 50 nm or smaller. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an oxide magnetic material used for a switching power supply transformer, a choke coil, etc., particularly a Mn-Zn ferrite material.

[0002]

2. Description of the Related Art Mn-Zn-based ferrites used for transformers, choke coils and the like are required to have lower loss as electronic devices become lighter, thinner and shorter. That is, if the loss is large, the circuit efficiency is deteriorated, and heat is generated, which adversely affects the electronic device.

The core loss of Mn-Zn type ferrite is generally considered to consist of hysteresis loss, eddy current loss and residual loss. In a low frequency range such as several KHz, the hysteresis loss is dominant, and the loss is reduced by increasing the crystal grain size of the sintered body. On the contrary, the eddy current loss is dominant in a high frequency region such as several MHz, and the loss is reduced by reducing the grain size of the sintered body.

[0004]

In the region around 100 MHz where the present material is generally used, the hysteresis loss and the eddy current loss have almost the same ratio to the total loss. Therefore, it becomes necessary to reduce the hysteresis loss and the eddy current loss in a well-balanced manner.

In order to reduce both hysteresis loss and eddy current loss, it is considered that uniform mixing of raw materials and additives is important. That is, by producing a more uniform state, it can be expected to obtain a material with less loss.

As a result of many studies for uniform dispersion, the present inventors have found that the average particle diameter of the additive, which is a subcomponent of Mn-Zn ferrite, is 100 nm or less, more preferably 5 nm.
It was found that the core loss can be reduced by mixing the particles with a thickness of 0 nm or less.

Further, it has been found that the core loss can be further reduced by adding not in the form of powder as it is when the additives are mixed, but in the state of already sufficiently dispersed slurry.

The present invention has been made on the basis of such findings, and its object is to provide Mn having a lower core loss than the conventional one.
A method for manufacturing a Zn-based ferrite material is provided.

[0009]

[Means for Solving the Problems]
Therefore, in the method of the present invention, the main component is Fe_TwoO_ThreeTo 50.0
~ 56.0 mol%, ZnO 5-20 mol%, MnO 3
Contains 0-45mol%, CaCO as an accessory ingredient_Three0.
03-0.1 Wt%, SiO_Two0.001-0.05
Wt%, TiO_Two0.2-0.4 Wt%, Co_ThreeO_Four
0.03 to 0.1 Wt%, ZrO_Two0.01 to 0.
Odor of Mn-Zn Ferrite Material Having 05 Wt%
Which constitutes the sub-component_Two, TiO_Two, Co_ThreeO
_Four, ZrO _TwoAt least one of which has an average particle size of 100 nm
Or less, more preferably 50 nm or less
It is characterized by.

In the present invention, among the above-mentioned subcomponents, especially T
The particle size of iO ₂ and ZrO ₂ is preferably 100 nm or less, more preferably 50 nm or less.

In the present invention, among the above-mentioned subcomponents, T
The particle size of iO ₂ is preferably 100 nm or less, more preferably 50 nm or less.

Further, in the present invention, when the additive as the accessory component is added to the raw material, it is added in the form of a dispersed slurry to obtain further preferable results.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The Mn-Zn ferrite material of the present invention contains Fe ₂ O ₃ as a main component in an amount of 50.0 to 56.0.
mol%, ZnO 5-20 mol%, MnO 30-45mo
It has a composition containing 1%.

Further, CaCO ₃ is added as an auxiliary component to 0.0
3 to 0.1 Wt%, SiO ₂ 0.001 to 0.05 W
t%, TiO ₂ is 0.2 to 0.4 Wt%, Co ₃ O ₄ is 0.03 to 0.1 Wt%, and ZrO ₂ is 0.01 to 0.0.
5 wt% is contained.

The method for producing a ferrite core using these main component and subcomponents is a conventional method. That is, a mixture of a predetermined amount of subcomponents added to the main component is mixed, calcined, pulverized into powder, and then granulated and molded, and then fired while strictly controlling the oxygen concentration, The oxide magnetic material has a shape, and is molded into a core shape of a switching power supply transformer or a choke coil according to its purpose.

In the above manufacturing method, the subcomponents are constituted.
SiO_Two, TiO_Two, Co_ThreeO _Four, ZrO_TwoLittle
At least one average particle size is 100 nm or less, and
Since it is preferably 50 nm or less,
It was confirmed that the core loss reduction effect was enhanced. In particular
TiO_Two, And ZrO_TwoAverage particle size of 100nm or less
And more preferably 50 nm or less, and
Especially TiO_TwoHas an average particle size of 100 nm or less, and
Further preferably, the thickness is 50 nm or less
Was found to be high.

It is presumed that the above-mentioned effects are due to the fact that the smaller the particle size of the accessory component, the more uniform the particles can be dispersed among the main-component crystal particles, and the higher the loss-reducing effect.

Further, when the additive which is a sub ingredient in the above-mentioned manufacturing method is added to the raw material, the effect is further enhanced by adding it in the form of a dispersed slurry. It is presumed that even more uniform mixing and dispersion can be carried out by adding a sufficiently dispersed slurry.
Moreover, since the average particle size of the subcomponents is extremely fine, it is difficult to add them as powders, and the addition of a fixed amount becomes easy by making them into a slurry.

<Example> The Mn-Zn-based ferrite of the present invention
Fe is the main component_TwoO_Three, ZnO, MnO
Using materials, CaCO as an accessory component_Three, SiO_Two，
TiO_Two, Co _ThreeO_Four, ZrO_Two  Includes 5 ingredients
Configured as And the mixing conditions of the main components are
When used in transformer cores, etc., the desired characteristics can be obtained.
As shown in the following range.

(A) Main component Fe ₂ O ₃ 50.0 to 56.0 mol% ZnO 5 to 20 mol% MnO 30 to 45 mol%

The mixing ratio of the subcomponents is as follows. (B) subcomponent _{CaCO 3 0.03~0.1Wt% SiO 2 0.001~0.05Wt%} TiO 2 0.2~0.4Wt% Co 3 O 4 0.03~0.1Wt% ZrO 2 0 0.01-0.05 Wt%

Seven kinds of the above-mentioned additives having various particle diameters and states at the time of addition were made as prototypes to give Examples 1 to 7. The results are shown in Table 1.

Then, a mixture obtained by adding a predetermined amount of (b) to (a) was mixed, calcined and pulverized by a conventional method to obtain a powder.
Then, after granulation and molding, firing was performed while strictly controlling the oxygen concentration to produce an oxide magnetic material.

Core loss at 100 KHz, 200 mT, and 80 ° C. was determined for the produced Mn-Zn ferrite according to the magnetic core loss measuring method specified in JIS C 2561-1992. The results are also shown in Table 1.

[0025] For <Comparative Examples 1 and 2> same main component, was added the same secondary components have been forming the oxide magnetic material by a conventional method, except for SiO _2, conventional additives particle size 200 Three
00 nm powder is used. Table 1 also shows the particle size, the state at the time of addition, and the core loss.

[0026]

[Table 1] From Table 1, the cores obtained in Examples 1 to 7 are Comparative Example 1 and
It was confirmed that the core loss as a whole was lower than that obtained in 2.

Considering each example, it can be concluded as follows. First, in comparison between Example 7 and Comparative Examples 1 and ₂ , focusing attention on TiO ₂ as a subcomponent,
The core loss is improved by using it as a powder of 00 nm.

In Example 6, it was found that the core loss was further improved by setting the same TiO ₂ to 36 nm.

Further, it was confirmed that the core loss was further improved by mixing in the state of a sufficiently dispersed slurry as in Example 5.

It is presumed that by making the grain size of TiO ₂ fine as described above, the dispersion of TiO _{2 in} ferrite becomes good and the core loss is improved.

If an intra-grain solid solution type additive such as TiO ₂ is mixed non-uniformly, the TiO ₂ concentration in each crystal grain of ferrite differs, and as a result, the temperature characteristics vary depending on each crystal grain. It is thought that the hysteresis loss and the eddy current loss are deteriorated and the core loss is increased.

Therefore, rather than adding as powder,
It is presumed that aggregation of the additive is prevented in a sufficiently dispersed slurry state, and more uniform dispersion is obtained, so that the core loss is further improved.

In Example 4, Co ₃ O _4, which is an intragranular individual-solution type additive like TiO ₂ , has a particle size of 15 nm, and when added in a slurry form, some core loss is caused. Although an improvement was seen, it was not seen as much as TiO ₂ .

In Example 3, SiO ₂ was added as a slurry, and although a slight improvement in core loss was observed, no significant effect was observed. This is probably because SiO ₂ has a very small particle size of 10 nm and the addition amount is very small compared to other additives.
It is highly probable that the effect was not significant.

In Example 2, the core loss was improved by adding ZrO ₂ as a powder of 35 nm.

Further, in Example 1, ZrO ₂ , Co ₃ O
_By adding ₄ and SiO ₂ as a sufficiently dispersed slurry, a low loss material of 230 KW / m ³ could be obtained.

In comparison with Examples 3 and ₄ , considering that the effects of Co ₃ O ₄ and SiO ₂ are limited in Examples 3 and ₄ , Example 1 is mainly due to the effect of ZrO ₂ . It is considered that the core loss can be improved by adding a grain boundary precipitation type additive such as ZrO ₂ to a fine particle size and adding it as a dispersed slurry in the same manner as the intragranular solid solution type additive. Was found. From this, if the grain boundary precipitation type additive is mixed non-uniformly, the ferrite grain boundary has a thin crystal structure of about several nm, so the thickness varies depending on the location of the grain boundary, resulting in deterioration of eddy current loss. It is concluded that homogeneous mixing is of particular importance.

[0038]

As described in the above examples, according to the method for producing a Mn-Zn ferrite material of the present invention,
Even if the composition is the same as the conventional one, it is advantageous to reduce the core loss of the ferrite core by reducing the particle size of each material as the accessory component and devising the addition method.

Claims (4)

[Claims] 1. Fe ₂ O ₃ as a main component is 50.0 to 5
6.0 mol%, ZnO 5-20 mol%, MnO 30-
Contains 45 mol% and contains 0.03 of CaCO ₃ as an accessory component.
~0.1Wt%, 0.001~0.05Wt the SiO ₂
%, TiO ₂ is 0.2 to 0.4 Wt%, Co ₃ O ₄ is 0.03 to 0.1 Wt%, and ZrO ₂ is 0.01 to 0.0.
In the Mn-Zn-based ferrite material having 5 Wt%, SiO ₂ , TiO ₂ , and Co ₃ O constituting sub-components.
₄ , at least one of ZrO ₂ has an average particle size of 100 nm
It is below, More preferably, it is 50 nm or less, The manufacturing method of Mn-Zn type | system | group ferrite material characterized by the above-mentioned. 2. The method according to claim 1, wherein among the accessory components, T
A method for producing a Mn—Zn-based ferrite material, wherein the average particle size of iO ₂ and ZrO ₂ is 100 nm or less, more preferably 50 nm or less. 3. The method according to claim 1, wherein among the accessory components, T
A method for producing a Mn—Zn-based ferrite material, characterized in that the average particle size of io ₂ is 100 nm or less, more preferably 50 nm or less. 4. The method for producing a Mn-Zn ferrite material according to claim 1, wherein the additive as an accessory component is added in the form of a dispersed slurry when added to the raw material.