JPH0443612A - Manufacture of magnetic oxide material - Google Patents

Abstract

PURPOSE:To eliminate instability of product characteristics due to volume expansion caused by interphase formation at the time of baking, and improve porcelain characteristics, by oxidation-roasting chloride of Fe or raw material wherein one or more kinds of chloride of Mn, Mg and Ni are added to said chloride of Fe, and adding Zn in the form of ZnFe2O4 or ZnMn2O4 to the obtained oxide. CONSTITUTION:Oxide as the raw material is obtained as follows; chloride of Fe or material wherein one or more kinds of oxide of Mn, Mg and Ni are added to said chloride of Fe is oxidation-roasted. According to necessity, oxide, hydroxide and carbonate of Mn, Mg and Ni are added to the oxide obtained by oxidation-roasting. Further, as a Zn source being the principal object, ZnFe2 O4 or ZnMn2O4 is added in the state of powder or slurry liquid; composition compounding is performed so as to conform with objective material quality; obtained material is sufficiently mixed for homogenizing by using a ball mill or the like. After that, the material is dried, molded by pressing with a metal mold conforming with the product shape, and finally completed by baking. Thereby a sintered core excellent in ceramic characteristics can be stably manufactured without passing through calcination process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a method for producing ferrite, and in particular, an oxidation method capable of stably producing rough 1-ferrite with high dimensional accuracy and excellent magnetic properties. The present invention relates to a method for manufacturing a magnetic material.

[Prior Art] The manufacturing process of ferrite usually uses Fe, Mn, and Mg, which are the main elements contained in ferrite.

This is carried out by mixing individual oxides such as Ni, Cu, Zn, etc. or compounds such as carbonates in a predetermined ratio, followed by calcining, crushing, and molding. In addition, as shown in Japanese Patent Publications No. 47-11550 and No. 63-17776, oxides obtained by oxidative roasting of a solution containing some of the chlorides of the elements constituting ferrite are used. There is a technology that uses it as a raw material, and in this case it is said that the calcination step can be omitted.

In the above manufacturing process, ZnC1ZnO, which is a main element constituting ferrite, is added in the form of a compound.

In the technology disclosed in Japanese Patent Publication No. 63-17776, the vapor pressure of bent lead chloride is high and it volatilizes during oxidation roasting, so it cannot be roasted at the same time as Fe and Mn chlorides. It is added as ZnO in the raw material mixing process.

After mixing, these raw material oxides react with each other through the addition of thermal energy during calcination and firing, forming an intermediate phase.
Eventually, a single phase with a spinel structure is formed.

By the way, in these phase changes, ZnO forms ZnFe2O+ and ZnMn2O4 as an intermediate phase, but the former in particular undergoes a volumetric expansion of 1.5 to 2% during the reaction of ZnO+Fe2O3-ZnFe2O4, resulting in the formation of a press-formed product. On the other hand, expansion and subsequent contraction due to sintering add cyclic stress, which has negative effects such as a decrease in the final sintered density, deformation and cracking of the product, and a decrease in dimensional accuracy. Improvement was desired. The above effects are particularly noticeable when calcination is omitted.

[Problems to be Solved by the Invention] In view of the problems of the conventional ferrite manufacturing process described above, the present invention is a process that omits the calcination required to manufacture ferrite with excellent magnetic properties. The purpose of this study is to improve the instability of product properties due to volume expansion caused by mesophase formation during sintering, and to propose a method for stably producing ferrite with excellent magnetic properties.

[Means for Solving the Problems J] The present invention is based on Fe, which is a main element constituting Ferrite 1-.
chloride or further Mn, Mg.

A raw material containing one or more Ni chlorides is oxidized and roasted, and Zn is added to the resulting oxide as Z n F e 2O4 or Z n
This is a method for producing a raw material oxide magnetic material for soft ferrite, which is characterized in that M n 2O4 is added.

According to the present invention, compared to the use of ZnO in the prior art, in addition to not causing volume expansion during the firing process, the properties of ferrite are significantly improved by adding ZnFe2O4 or ZnMn2O4 to the mixture. It has the effect of improving the homogeneity of the final composition, which has a great influence, and the magnetic properties of the product are significantly improved.

ZnFe2O4 and ZnMn2O4 are Zn.

It can be easily obtained by heat treating Fe, Mn oxides, carbonates, or chlorides at 400 to 800°C, which is lower than the normally used calcination temperature, and calcination can be omitted. Since excellent magnetic properties can be stably obtained, there is sufficient economic effect.

[Operation J] In the present invention, the raw material used is an oxide obtained by oxidative roasting of Fe chloride or one or more of Mn, Mg, and Ni chlorides added thereto.

Especially in retrospect, the main elements that make up ferrite are
It is more desirable to use a mixed oxide containing more than one species from the viewpoint of ferrite properties and economic efficiency. The chloride may be in the form of powder or solution).

If necessary, Mn, M
g, Ni oxides, hydroxides, and carbonates are added, and ZnFe2O< or ZnMn2O4 is added as a powder or slurry liquid as a Zn source, which is the main focus of the present invention, to form the target material. Blend the ingredients using a mixer and thoroughly mix using a ball mill or the like for homogenization.

Kowa et al.'s Zn source (ZnFe2O4) is added during the oxidation roasting process, and may be added in advance in the oxidation roasting furnace. Adding it in the oxidation roasting furnace has the advantage of further increasing the uniformity of the composition. be.

After that, it is dried and granulated by adding a binder such as PVA.
Furthermore, it is molded using a mold that matches the shape of the product using a press.

The final core firing is 1250 to 1
It is carried out under a temperature condition of 400° C., preferably in an atmosphere with controlled oxygen partial pressure.

If the calcination step is omitted, 7. Z n O as n source
When Zn source is used, abnormal grain growth occurs and deformation/cracks occur frequently.
By using n, the above-mentioned problems do not occur at all, and very excellent magnetic properties can be obtained. This is because no expansion occurs during the phase change during the firing process, and the homogeneity of the composition ultimately improves. In addition, 5i02. Even if a small amount of additives such as Cab and Nb2O5 are added, the effects of the present invention are not lost.

[Example] The specific configuration of the present invention and its effects will be illustrated by the following example.

Example 1 The weight ratio obtained by oxidizing and roasting a mixed chloride of FeCff2 and MnCβ2 is Fe2O3 : Mn2O3 = 70.3 + 2
ZnFe2O4 powder was added to the mixed oxide of 9.7 so that the molar ratio was Fe2O3:MnO:Zn0 = 53+35:1.2, and then S
Add 140 ppm of i02, 350 ppm of CaCO3 in terms of CaO, and 150 ppm of Nb2O5, mix in a ball mill, omit the calcination step, add PVA as a binder, granulate, and then press-form the toroidal core with red color. It was fired at 1320°C.

On the other hand, as Comparative Example 1, Z n Fe
A core was prepared using the same process as above except that ZnO was added instead of 2O4. Further, as Comparative Example 2, a toroidal core was produced by mixing the above mixed oxide ZnO and then calcining it at 900°C. Table 1 shows the density and magnetic properties measured for the obtained sintered core.

In the sintered core of Comparative Example 1, abnormal grains with significant grain growth were observed in some parts, and as a result, the magnetic properties were inferior. In addition, some cores had cracks at some corners.

As is clear from Table 1, according to the method of the present invention, ZnO
It can be seen that superior properties can be obtained compared to Comparative Example 2, which was treated by the conventional method of adding and performing calcination.

Example 2 Fe2 was added to iron oxide obtained by oxidative roasting of Fe chloride.
03 :MnO: Zn0=53 2 35
: Mn3O4 and ZnM so that it becomes 12 (mol%)
Add n2O4 powder, further add 140ppm of SiO2, C
aCO3 is 350 ppm in terms of CaO, Nb2O5 is 1
50 ppm was added and mixed in a ball mill, the calcination step was omitted, PVA was added, granulated, press-molded into a toroidal core, and fired at 132O<0>C. Comparative example 3.4 is!
A sample to which ZnO was added was prepared in the same manner as in Comparative Example 1.2.

The measurement results of the density and magnetic properties of the obtained sintered core were
Shown in the table.

As in the case of Example 1, it can be seen that soft ferrite with much better density and magnetic properties than Comparative Example 3.4 can be obtained.

Table 1 Table 2 [Effects of the Invention 1 As stated above, the effects of the present invention are obtained by oxidizing and roasting Fe chloride constituting ferrite or a chloride containing one or more of Mn, Mg, and Ni. By using ZnFe2Q4 or ZnMn2O4 as a Zn source in the resulting oxide, a sintered core with excellent magnetic properties can be stably produced through a calcination process.

Claims (1)

[Claims] 1. Fe chloride or Mn, Mg, Ni
A method for producing a raw material oxide magnetic material for soft ferrite, which comprises oxidizing and roasting a raw material to which one or more chlorides have been added, and adding ZnFe_2O_4 or ZnMn_2O_4 to the obtained oxide.