JPH06325919A - Oxide magnetic material and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an oxide magnetic material, which has a uniformly increased crystal grain diameter and consists of an Mn-Xn ferrite having a superior high magnetic permeability and a low loss, and a method of manufacturing the oxide magnetic material. CONSTITUTION:An oxide magnetic material is a spinel type Mn-Zn ferrite sintered body, contains at least one kind of a compound of 0 to 0.4wt.% (0 is not included). out of TiO2 and SnO2 and the mean crystal grain diameter of the material is 20 to 50mum. This oxide magnetic material is obtained by comprising a process/wherein at least one kind of a compound of 0 to 0.4wt.% (0 is not inlcuded). out of the Tie, arnd the SnO2 is added to Mn-Zn ferrite raw powder in such a way that the one kind of the compound is contained in the raw powder, and a process/wherein a heat-up firing is performed in an atmosphere of the partial pressure of oxygen of at least 10 %, in a method of manufacturing the Mn-Zn ferrite sintered body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to spinel type Mn-Zn.
The present invention relates to a material having high magnetic permeability and low loss in ferrite and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, technological innovations for miniaturization and high performance of electronic devices have been remarkably accompanied, and accordingly, high performance of Mn-Zn ferrite used, for example, high magnetic permeability and low loss are strongly desired.

Generally, Mn-Zn ferrite having a high magnetic permeability has a main composition of 52 to 52.5 mol% Fe ₂
The composition of O ₃ , 24-26 mol% MnO balance ZnO is in the vicinity, and that of commercially available products is almost in this range.

Further, the Mn-Zn ferrite may contain SiO ₂ and CaO as sub-components.
This is done especially for the purpose of improving the frequency characteristic of initial permeability (μ _i ) and controlling grain growth.

In order to achieve a high μi, it is extremely important not only to examine the composition as described above and select the optimum composition but also to make the crystal grain size relatively large.
For this purpose, it is most effective to raise the firing temperature.

More specifically, in order to increase the magnetic permeability of Mn-Zn ferrite, it is indispensable not only to examine the composition as described above but also to make the crystal grain size uniform and large.

Normal Mn-Zn ferrite is manufactured through the steps of mixing, pre-firing, crushing, granulation, molding and sintering.
Among these, in order to control the crystal grain size of the fired body, it is essential to set the powder grain size after firing and firing conditions, especially the firing temperature to appropriate conditions.

The powder particle size is usually about 0.1 to 0.5 μm, which is determined by the raw material used and each manufacturing condition. The firing temperature is 1200 to 1450 in consideration of the life of the furnace and the volatilization of Zn.
It is customary to carry out between 0 ° C. Firing at a temperature as high as possible within this firing temperature range is an essential condition for increasing the crystal grain size and obtaining high magnetic permeability.

[0009]

However, if the firing temperature is too high, the grain size distribution due to abnormal grain growth becomes broad at the stage of grain growth, or there is a structural irregularity such as pores left in the grain. However, there is a drawback that the magnetic properties are deteriorated remarkably, for example, the magnetic permeability and the loss properties are deteriorated.

For this reason, the high-permeability materials currently on the market are controlled to have a crystal grain size of at most 15 to 20 μm and a μ _{i of} at most 10,000. This is because the above-mentioned drawbacks occur when the crystal grain size is further increased.

Therefore, the technical problem of the present invention is to solve the above-mentioned drawbacks and to provide an oxide magnetic material made of Mn-Zn ferrite which is excellent in high permeability and low loss by uniformly increasing the crystal grain size, and a manufacturing method thereof. To provide.

[0012]

Means for Solving the Problems As a result of various investigations, the present inventor has added at least one of TiO ₂ and SnO _{2 in} an amount of 0 to 0.4 (not including 0) wt% to obtain an average crystal grain. It was found that the diameter is 20 to 50 μm and the structure has a uniform structure, and high permeability and low loss can be realized. Furthermore, the atmosphere in the temperature rising part during the firing process has a significant effect on the grain growth of Mn-Zn ferrite. The inventors have found that, particularly when the oxygen partial pressure is 10% or more, higher permeability and lower loss can be achieved. Further, the present inventor not only solved the main problem by adding one or more of TiO ₂ or SnO ₂ , but not only Ti
It was found that the essential permeability and loss can be improved by containing O ₂ and SnO ₂ , and the present invention has been accomplished.

According to the present invention, the spinel type Mn-Zn ferrite sintered body contains 0 to 0.4% by weight (not including 0) of at least one of TiO ₂ and SnO ₂ , and has an average crystal grain size. Of 20 to 50 μm is obtained.

That is, in the present invention, by adding an appropriate amount of TiO ₂ and SnO ₂ , abnormal grain growth can be suppressed and a fired body having a uniform and large crystal grain size can be obtained.
As a result, it is possible to achieve extremely high magnetic permeability and low loss.

Here, in the present invention, TiO ₂ , SnO
_Although the details of the mechanism of suppression of abnormal grain growth by the addition of ₂ are unclear, it is thought that these additions improved the state of the grain surface and grain boundaries and promoted smooth normal grain growth. Be done.

Here, in the present invention, TiO ₂ , Sn
The content of O ₂ is set to 0 to 0.4 wt% (0 is not included), in the region of 0.4 wt% or more, not only there is no further effect, but on the contrary, abnormal grain growth occurs and magnetic characteristics Is deteriorated.

Further, according to the present invention, in the method for producing a Mn-Zn ferrite sintered body, at least one of TiO ₂ and SnO ₂ is added to the Mn-Zn ferrite raw material powder in an amount of 0 to 0.4% by weight ( A method for producing an oxide magnetic material is obtained, which comprises adding so as to include (not including 0) and performing temperature rising firing in an atmosphere having an oxygen partial pressure of at least 10%.

Here, in the present invention, the oxygen atmosphere in the temperature rising portion in the firing step is limited to 10% or more of oxygen because the pores are left in the grains when the oxygen partial pressure is lower than 10%. This is because abnormal grain growth is likely to occur and the magnetic properties are deteriorated. The oxygen partial pressure is up to 100%, which has the effect of suppressing abnormal grain growth. However, industrially, it is preferable in terms of cost to perform it in air. ， In addition, the effect is sufficient even in the atmosphere.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 High-purity Fe ₂ O ₃ and Mn ₃
Using O ₄ and ZnO raw materials, mixing with a ball mill to obtain 52mo
1% Fe ₂ O ₃ -25 mol% MnO-23 mol% Z
A mixed powder having a composition of nO was obtained. This mixed powder was pre-baked at 1000 ° C. in the atmosphere. Further, this powder was pulverized with a ball mill. At this time, TiO ₂ and SnO ₂ are simultaneously added to 0
0.5 wt% was added. Polyvinyl alcohol was added as a binder to the obtained pulverized powder, and spray-returned. After that, at a pressure of 2 tons / cm ² , the outer diameter is 25 mm,
A toroidal shape with an inner diameter of 15 mm and a height of 5 mm is formed, and the oxygen partial pressure is 0.1 to 6% at a temperature of 1300 to 1400 ° C.
Firing was performed in a controlled atmosphere between the two. In Table 1,
The magnetic properties when the added amounts of TiO ₂ and SnO ₂ are changed, and the average particle size obtained from the section length using an image analysis processing device are shown.

[0021]

[Table 1]

As shown in Table 1 above, TiO ₂ , Sn
At least one type of O ₂ is in the region of 0.4 wt% or less (0
It can be seen that the crystal grains are large and excellent magnetic characteristics are obtained.

(Example 2) 52Fe obtained in Example 1
₂ O ₃ -25 MnO-23 ZnO (mol%) TiO
₂ is 0.3 wt%, SnO ₂ is 0.3 wt%, TiO ₂
Of 0.05% by weight and 0.1% by weight of SnO ₂ were added to each of the three samples, and the oxygen partial pressure during heating was 0.005 to 10%.
Change to 0%, hold temperature 1300 ~ 1400 ℃,
It was fired under the condition that the oxygen partial pressure of the holding part was controlled at 0.1 to 6%.

In Table 2 below, the magnetic characteristics when the oxygen partial pressure at the time of temperature rise was changed and the cut side length of the crystal structure with firing obtained by using the image analysis processing apparatus were obtained, and this average value was calculated as 1 The average crystal grain size of the value obtained by multiplying by 0.5 is shown.

[0025]

[Table 2]

As shown in Table 2 above, in any of the samples having any composition, when the oxygen partial pressure during heating was 10% or more, the average particle size was 20 μm or more, and no abnormal grain growth was observed.
Further, it can be seen that the magnetic properties are superior to those of the sample in which the oxygen partial pressure lower than 10% is increased.

[0027]

As described above, according to the present invention, SnO
₂ , at least one of TiO ₂ and 0 to 0.4 wt%
(0 is not included) Contains and average crystal grain size is 20-50 μm
It is possible to obtain Mn-Zn ferrite having high magnetic permeability and low loss.

Further, since the above Mn-Zn ferrite is manufactured, the oxygen partial pressure in the temperature rising portion in the firing process is set to 10% or more to obtain Mn-Zn ferrite with higher permeability and lower loss. is there.

This is because not only is it possible to realize smooth normal grain growth by containing a specific amount of TiO ₂ and SnO ₂ and to obtain an extremely homogeneous fired body structure and to realize high characteristics, but also TiO ₂ and SnO 2. It seems that the addition of ₂ improved the essential magnetic properties of the spinel phase.
It is also considered that smooth normal grain growth was further promoted by setting the oxygen partial pressure of 10% or more in the temperature rising portion in the firing process.

Claims (2)

[Claims] 1. A spinel-type Mn—Zn ferrite sintered body containing at least one of TiO ₂ and SnO _{2 in} an amount of 0 to 0.4% by weight (not including 0) and having an average crystal grain size of 20 to 50 μm. An oxide magnetic material characterized by: 2. A method for producing a Mn-Zn ferrite sintered body, wherein the Mn-Zn ferrite raw material powder is Ti
Add at least one of O ₂ and SnO ₂ so as to contain 0 to 0.4% by weight (not including 0), and perform temperature-rising firing in an atmosphere having an oxygen partial pressure of at least 10%. A method for producing an oxide magnetic material, comprising: