JPS6177304A - Manufacture of mn-zn ferrite - Google Patents

Abstract

PURPOSE:To attain exellent magnetic characteristics without producing abnormal crystal formation, by adding CaO, and one kind of alkali metals, alkaline earth metals, and silicate of Zr or Al of predetermined amounts into principal composition consisting of Fe2O3, MnO, ZnO of predetermined proportions, and by fine- grinding, molding, and sintering them. CONSTITUTION:After CaO of 0.01-0.2wt% and one kind of alkali metal,s alkaline earth metals, and silicate of Zr or Al of 0.005-0.2wt% are added into calcined raw material of principal composition consisting of FeO3 of 50-70mol %, MnO of 10-40mol%, and ZnO of 5-30mol%, they are fine-ground, molded, and sintered. CaO is added for the purpose of providing low magnetic loss. Adding one kind of a alkali metals, alkaline earth metals, and silicate of Al or Zr can prevent large-size crystal formation which would be produced by being added in the form of SiO2, and can attain excellent magnetic characteristics.

Description

[Detailed description of the invention] Industrial field of application The present invention relates to a method for manufacturing Mn-ZTI ferrite, which produces excellent magnetic properties, especially low magnetic loss properties, without producing abnormal crystal structures even at high sintering temperatures. have h
-Regarding a method for manufacturing zη-based ferrite.

BACKGROUND TECHNOLOGY tln-Zn ferrite is widely used in various consumer devices such as communication equipment, electronic computers, VTRs, and magnetic heads.
Improvements have been made to suit each application.

Due to the miniaturization and higher performance of today's equipment,
There is a need for magnetic materials with low magnetic loss.

In such Mn-ZTI ferrite, residual loss.

Conventionally, as a method for obtaining materials with low hysteresis loss and eddy current loss, oxides of alkali metals and alkaline earth metals or Mn containing Al2O3, ZrO2 and CaO have been used.
-ZTI-based ferrite has been proposed, and furthermore, CaO
A well-known method is to increase the electrical resistance and improve the magnetic properties by adding 5LO2 and 5LO2 in combination. but,
When the sintering temperature is raised to improve the density of the material, an abnormal sintering reaction occurs, resulting in a sintered structure that is a mixture of large and small crystals, which can easily lead to deterioration of magnetic properties. there were.

In general, in the production of MiZn-based ferrite, additives are added singly or in combination in the form of single oxides to the raw material of the basic composition during pulverization before calcination, or during the pulverization of the calcination raw material of the basic composition. After that, it was molded, fired, or further subjected to hot isostatic pressing. However, with conventional manufacturing methods, there is a limit to improving the magnetic properties of ferrite with the above composition, and 1-
7Tl-based ferrite was not detected.

Purpose of the Invention In view of the current state of the Mn-ZTI ferrite described above, the present invention has been made to develop a Mn-ZTI ferrite that can obtain excellent magnetic properties even at high sintering temperatures without forming an abnormal crystal structure, and has especially low magnetic loss properties. For the purpose of ZTI ferrite, r
The object of the present invention is to provide a manufacturing method that can improve the magnetic properties of Zn-based ferrite.

Structure and Effects of the Invention The present invention utilizes the commonly practiced manufacturing process of Mn-Zn ferrite, that is, adding additives to the original lit of the basic composition during mixing before calcination, or changing the basic composition. As a result of various studies on the process of adding raw materials during pulverization and then molding, sintering, or further hot isostatic pressing, in particular, the process of blending additive raw materials, we found that:
CaO and alkali metal, alkaline earth metal or Z
An additive raw material consisting of one type of silicate of AI is mixed and added during the pulverization of the calcined raw material of the basic composition, and after being finely pulverized, it is molded, sintered, or further subjected to hot isostatic pressing treatment. It has been discovered that by doing so, it is possible to obtain Mn--Zn-based ferrite with much improved magnetic properties compared to conventional manufacturing methods.

That is, this invention: Fe20350-70 mol%.

Mn010-40 mol%.

ZTIO 5-30 mol%.

With respect to the basic composition consisting of: 0.01 wt% to 0.2 wt% of CaO and 0.005 wt% to one type of silicate of alkali metal, alkaline earth metal, or Zr, H
0.2wt% is blended and added to the calcined raw material having the above basic composition, which is pulverized, then molded and sintered.
This is a manufacturing method.

The reason why an n-Zn ferrite with excellent magnetic properties can be obtained in this invention is as follows.

In order to increase the magnetic permeability, reduce the coercive force, and reduce the potash magnetic loss of water-based ferrite, Ca is added as an additive.
0.5LO2 and oxides of alkali metals or alkaline earth metals, or M2O3, ZrO2, etc. are added in combination and sintered at high temperatures to increase the sintered density. A layer with high electrical resistance is formed. However, 5LOp generally tends to induce a coarse crystal structure and destroys a high electrical resistance layer, resulting in a deterioration of magnetic loss. Therefore, this 5LO2 can be used as additives such as alkali metals, alkaline earth metals, or 7. When r, AJ is added in the form of a silicate, a coarse crystal structure is hardly generated even during high temperature sintering, a uniform crystal structure is obtained, and excellent magnetic properties are obtained.

In this invention, the alkali metal silicate is t11a2
Ca si Oa, Mg5L are preferable, and as alkaline earth metal silicates, Ca si Oa, Mg5L are preferable.
Os, Ba5jO3,5rSLOs are preferred.

Reason for Limiting the Composition The reason for limiting the basic composition and the composition of additives in the oxide magnetic material according to the present invention will be explained below.

The basic composition of Mn-Zn ferrite is Fe2035
o to 70 mol%, MnO 10 to 40 mol%.

The reason why the ZnO content is 5 to 30 mol % is that if the composition is other than this, the magnetic permeability will be extremely low and the coercive force will also be too large to be practical as a soft magnetic material.

CaO is added to obtain low magnetic loss, but 0.0
If it is less than 1 wt%, the electrical resistance becomes small and the required magnetic properties cannot be obtained, and if it is added more than 0.2 wt%, abnormal structures are likely to occur when the sintering temperature is increased to increase the density. Therefore, from 0.01 wt% to 0.2 wt
%wt%.

It is a feature of this invention that one of silicates of alkali metals, alkaline earth metals or M, Zr is added, and 5
It is added in the form of id2, which prevents the formation of a coarse crystal structure and provides excellent magnetic properties.
If it is less than 0.005wt%, the above effect will be small, and if it is less than 0.005wt%,
．． If it exceeds 2 wt%, a coarse crystal structure will be generated when the firing temperature is increased to increase the density.
,005wt% to 0.2wt%.

Further, as the main raw materials and additives in this invention, compounds that become oxides upon firing can be used.

Example Fe2O3 53 mol%, bar n0 31 mol%, ZnO1
6 mol%.

After blending and mixing raw materials with a basic composition of 850
Temporary firing was performed at ℃.

When pulverizing the above basic composition calcined raw material with a ball mill, 1
For the basic composition, as shown in Table 1, CaO,
Zr5LOt, /V 203 3SL 02, Na2S
iO3, K2Sε0. In addition, as shown in Table 2, to CaO, Ca5LO2, M
g SL O3, Ba Si o8, Sr SL 02
Additive raw materials were blended, mixed and ground in the form of a composite addition.

Thereafter, it was molded into a ring shape with dimensions of 36 mm outer diameter x 24 mm inner diameter x 6 mm height, and was further fired at 1250° C. for 3 hours in a nitrogen gas atmosphere with controlled oxygen concentration.

The magnetic properties of the obtained fired product were measured and the results are shown in Tables 1 and 2.

For comparison, we also used additive raw materials in the form of single oxides.
When pulverizing the calcined raw material of the basic composition, other than addition pulverization,
Basic composition, amount of additives, and molding.

The magnetic properties of the comparative fired products were measured under the same firing conditions as the inventive examples (positive 1 to 12.25 to 36),
Not shown in Tables 1 and 2.

The core loss in Tables 1 and 2 was determined by winding the ring-shaped fired product, passing an alternating current of 100k)-1z, and measuring the core loss at 2000G.

As is clear from Tables 1 and 2, by adding and blending the additive raw materials in the form of CaO and silicate, which are the characteristics of this invention, at the time of pulverization of the basic composition, Mn-Zn-based ferrite can be made with low core loss. It can be seen that there is a remarkable effect on reducing the magnetic properties and improving the magnetic properties.

Margin below

Claims (1)

[Claims] Fe_2O_3 50 mol% to 70 mol%, MnO 1
0 to 40 mol%, ZnO 5 to 30 mol%, CaO 0.01 wt% to 0.2 wt%, and one type of silicate of alkali metal, alkaline earth metal, or Zr, Al. .005wt%~
A Mn-
A method for manufacturing Zn-based ferrite.