JPS623070A - Manufacture of high density ferrite sintered body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a high-density sintered ferrite body used in producing magnetic materials for the electronic industry.

[Conventional technology]

Conventionally, Fe2O2 has been used as the raw material powder for ferrite.

There are coprecipitation raw material powders made by neutralizing and precipitating metal oxides and metal carbonates such as MnCO3, Mn3O4, NiO, and ZnO, as well as sulfate solutions of each metal with alkali, and these can be used to make ferrite sintered bodies. I was creating it.

[Problem that the invention seeks to solve]

However, when these raw materials are used, hot-press sintering is difficult to achieve with hot isostatic pressing (HIP), because the normal firing method in which the firing atmosphere is controlled can only yield products with a theoretical density of 95 to 9 borders. High-density ferrite sintered bodies are manufactured using sintering methods. However, these methods have the disadvantage that the cost of the product inevitably increases due to the process.

[Purpose of the invention]

An object of the present invention is to provide a high-density ferrite sintered body at low cost.

[Means for solving problems]

The present invention relates to a method for producing a high-density ferrite sintered body, which is characterized by press-molding raw material ferrite powder whose main component is spinel ferrite powder having a plate-shaped particle shape and firing the molded material.

In the present invention, the raw material spinel ferrite powder with a disc-shaped particle shape is 1, for example, 20 g of γ-Fe with a disc-shaped particle shape.
and a hydroxide or oxide of manganese, zinc, nickel, etc. at a temperature of 700°C or below, preferably 550-70°C.
It can be manufactured by a method of heat treatment and sintering at a temperature of 0°C. γ-F8203, which has a plate-like particle shape, is produced by mixing a ferric salt such as ferric chloride with an alkali such as sodium hydroxide, and adding an oxyalkylamine such as ethanolamine to the ferric salt in the presence of water. Add 30 to 80 times the mole amount.

The reaction was carried out to obtain a slurry of ferric hydroxide, and the slurry was hydrothermally treated to obtain plate-shaped α-FeOOH.
H powder is heated and dehydrated to form a disc-shaped α-Fe203 powder,
This is reduced with a reducing gas such as hydrogen to form a plate-shaped Fe3O
It can be obtained by powdering 4 and then reoxidizing.

In the present invention, the high-density ferrite sintered body is produced by adding a binder such as polyvinyl alcohol to the raw material ferrite powder in the same way as in ordinary ceramic manufacturing methods, making it into a molded body, and then holding it in air up to about 500°C, then nitrogen. It can be produced by firing at a temperature of about 1,300 to 1,400° C. under an inert gas atmosphere such as the following.

In the present invention, when a material containing at least 60% by weight or more, preferably about 80% by weight or more of disk-shaped spinel ferrite is used as the main raw material, a remarkable effect on high density changes is observed. Additionally, additives may be added to the disk-shaped spinel ferrite powder in order to improve various properties. It is recognized that even if the additive is added in an amount of 20% by weight or less, the effect of producing a high-density sintered body of the present invention is not lost. - The raw powder of disc-shaped spinel ferrite used as the main component in the strength wood invention may be subjected to heat treatment such as calcination, but in that case, the calcination temperature becomes too high and the disc-shaped property is deteriorated. 3. If this occurs, the effects of the present invention will be lost. Furthermore, α-Fe20. If a single spinel phase with other phases is used, a high-density sintered body cannot be obtained. Therefore, in order to obtain the desired effects of the present invention, it is necessary that the main component raw material powder be disc-shaped and in a spinel phase.

〔Example〕

The present invention will be described in detail below with reference to Examples.

Example 1 Particle size 0.1 μm, platelet ratio 3.2. Specific surface area 27t
r? /f 53 mol% Fe2O3, 28 mol% Mob
, disk-shaped Mn-Zn with a composition of 19 mol% ZnO
A PVA (polyvinyl alcohol) solution having a concentration of 5% was added to the ferrite powder in an amount of 15% by weight and granulated, and a molded pellet of Logφ×5 strokes was produced at a compacting pressure of 1 t/cfA.

For comparison, plate-like γ-Fe203 and MnCO3, Zn
One using O granular α-Fe203 and MnCO3,
Those using ZnO were blended to have the same composition ratio and mixed in a ball mill. After drying, a part of each part was granulated to that point and then molded, and the remaining part was calcined in air at 800 to 1,000°C and ground again in a ball mill.

The mixture was mixed, dried, and then granulated to produce a molded body under the same conditions as above.

These molded bodies of Example 1 and comparative molded bodies were
After heating in air to burn the binder up to 500°C, the temperature was raised to 1300°C in N2 from 500°C, fired at this temperature for 3 hours, and then cooled in the same N2. Each sample was taken.

As a result of measuring the density of the obtained sintered body9, the density of the sintered body using the disk-shaped spinel 2 eliteite powder of the present invention was 99.512, which is the theoretical density, and the density of the sintered body using the disk-shaped spinel 2 eliteite powder of the present invention was 99.512, and the density of the other raw materials 9, for example, the disk-shaped γ -Fe203, MnCO3, Zn, and 0 without being calcined had a density of 95.6%.

The calcined one has 97.5% granular α-Fe203
.

Using MnCO3 and ZnO, the density was as low as 96 inches in the case without calcining, and 97 in the case in the case of calcining.

〔Effect of the invention〕

By using disc-shaped spinel 2 elite powder, various high-density Mn-Zn7 elite can be easily obtained.

When this ferrite was processed into a magnetic head, it had excellent wear resistance, which is an important property.

Claims (1)

[Claims] A method for producing a high-density ferrite sintered body, which is characterized by press-molding and firing a raw material ferrite powder whose main component is spinel ferrite powder with a plate-like particle shape.