JPH04328806A - Manufacture of manganese-zinc ferrite - Google Patents

Abstract

PURPOSE:To mass-produce an Mn-Zn ferrite material of high permeability and high density at low cost in a relatively short time of cycle of calcination using a continuous furnace. CONSTITUTION:In2O3 of 0.02 to 0.3wt.% is added to Mn-Zn ferrite material, and the mixture is calcined. The Mn-Zn ferrite material is composed of Fe2O3 of 50 to 58mol%, ZnO of 3 to 30mol%, and the remaining part consisting of MnO.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing manganese-zinc ferrite, and more specifically, by adding a small amount of In2O3 and firing, the present invention produces an oxide that exhibits high magnetic permeability characteristics in a short firing time. The present invention relates to a method of manufacturing a magnetic material.

0002

BACKGROUND OF THE INVENTION It is believed that increasing the magnetic permeability of ferrite can be achieved by increasing the grain size of the crystals, but this requires firing at high temperatures and for long periods of time. However, if the material contains zinc, such as manganese-zinc ferrite, if it is left in a high temperature state for too long, the zinc oxide will evaporate from the surface, resulting in a decrease in magnetic permeability. Therefore, according to the prior art, during firing, the ferrite material is covered with the same type of ferrite powder or some other kind of sealing, and the ferrite material is fired in a devised state to prevent the zinc from evaporating.

[0003] However, this method requires firing for a long period of time, such as several tens of hours, which increases the firing cost, and the process of removing the seal after firing increases the production cost, making it unsuitable for mass production as a whole. be.

[0004] Therefore, as a solution to these drawbacks, a small amount of MoO3 is added, and a low oxygen concentration (0.01 to 5%) is used to rapidly raise the temperature (the heating rate is 200 to 600 degrees Celsius at 1100°C or higher). A method for producing manganese-zinc ferrite has been developed in which the ferrite is sintered by sintering (1988-91908).

[0005]

[Problems to be Solved by the Invention] The method using rapid temperature rise described above is extremely effective in increasing magnetic permeability and density, but since firing is performed in an atmosphere with a low oxygen concentration, it is difficult to use a firing furnace that can be used. There are limitations and drawbacks such as high firing costs.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to create a manganese-zinc material that exhibits high magnetic permeability and can be mass-produced at low cost using a relatively short firing cycle using a continuous furnace. An object of the present invention is to provide a method for producing a ferrite-based ferrite.

[0007]

[Means for Solving the Problems] The present invention, which can achieve the above-mentioned objects, has a composition of manganese which has been generally used in the past.
Very small amount of In2 O3 in zinc-based ferrite material
This method involves adding and firing. The amount of In2O3 added is in the range of 0.02 to 0.3% by weight based on the manganese-zinc ferrite material which is the main component. The manganese-zinc ferrite material used here has a composition range that is almost the same as that of this type of material that is normally used as a high permeability oxide magnetic material, and has a composition range of 50 to 58 Fe2O3.
The composition is selected from a composition range in which ZnO is 3 to 30 mol% and the balance is MnO.

[0008] The firing of ferrite can be carried out in a continuous furnace in a firing cycle of 24 hours or less, and there is no need for special sealing or the like. Further, there is no need to pay particular attention to the temperature increase rate, temperature increase, and sintering atmosphere.

[0009]

[Function] The magnetic permeability of the manganese-zinc ferrite obtained by the above manufacturing method is much higher than that of conventional products. This is due to the following reasons. In2 O3 is 80
It decomposes at temperatures above 0°C and In2O sublimates. The presence of high-valent ions of sublimated indium near the grain boundaries increases the amount of vacancies of metal ions near the grain boundaries, increases the mobility of the grain boundaries, and promotes grain growth. In2O3 used in the present invention is similar to PbO, Bi2, which has similar effects.
Since the sublimation rate is lower than that of O3, MoO3, etc., there is no need to pay attention to the heating rate or heating atmosphere.
The amount of sublimation of InO2 is suppressed until the grain growth process reaches 300° C. or higher, and the grain growth promoting effect of InO2 is maintained. Finally, most of the added indium sublimes and does not remain near the grain boundaries, so there is no decrease in magnetic permeability due to grain boundary stress, and the magnetic permeability is 10,000.
A high magnetic permeability characteristic of about 0 or more is exhibited.

0010

[Example] Figure 1 shows manganese-zinc ferrite (Fe2
O3 53 mol%, ZnO 20 mol%, MnO
The graph shows the magnetic permeability when 0 to 0.4% by weight of In2O3 was added to 27% by mole) and firing was performed under three conditions. Table 1 shows the firing conditions.

[0011]

[Table 1]

[0012] Addition of a small amount of In2O3 causes a rapid increase in magnetic permeability. Even if the firing conditions change, In2 O3
The characteristic curve of magnetic permeability with respect to the amount of addition does not basically change. However, the properties are improved overall when firing is performed in the atmosphere (Example A). If the amount of In2O3 added is too large, the magnetic permeability decreases, so it is more preferably 0.03.
The content should be approximately 0.2% by weight.

[0013]

Effects of the Invention As described above, the present invention is a method in which a small amount of In2O3 is added to manganese-zinc ferrite and then fired.
Continuous grain growth is promoted above ℃, and finally I
Most of the nO2 sublimes and does not remain near the grain boundaries. Therefore, no decrease in magnetic permeability due to grain boundary stress is observed, and a high magnetic permeability of about 10,000 or more is exhibited. Furthermore, in the method of the present invention, high permeability magnetic materials can be mass-produced with a firing cycle of 24 hours or less and even at elevated temperature in the atmosphere, so the firing cost can be significantly reduced. Furthermore, as described above, in the method of the present invention, grain growth is promoted and additives do not remain at grain boundaries, so high-density oxide magnets such as cores for flyback transformers can also have high performance.

[Brief explanation of the drawing]

FIG. 1 is an In2O3 addition amount-magnetic permeability characteristic diagram with firing conditions as parameters.

Claims (1)

[Claims] [Claim 1] Fe2O3 50-58 mol%, Z
In2O3
A method for producing manganese-zinc ferrite, which comprises adding 0.02 to 0.3% by weight of manganese-zinc ferrite and firing.