JPH05315121A - Manufacture of ferrite - Google Patents

Abstract

PURPOSE:To provide the manufacture of a ferrite, which can lessen the dispersion of sintering density in every lot of ferrites simply. CONSTITUTION:46-51mol% iron oxide (Fe2O3), 11-16mol% nickel oxide (NiO, etc.), 28-34mol% zinc oxide (ZnO, etc.), and 3-13mol% copper oxide (CuO, etc.) are combined and mixed. The mixed material is roughly halved into two groups, and the respective groups are calcined for two hours at temperatures of 1100+ or -50 deg.C and 850+ or -50 deg.C so as to manufacture a first calcined substance (1100+ or -50 deg.C) and a second calcined substance (850+ or -50 deg.C). These two calcined substances are mixed and baked by specified quantities. Hereby, even if the baking temperature is dispersed, specified cavity ratio can be gotten.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ferrite used in a core for a cylindrical rotary transformer or the like.

[0002]

2. Description of the Related Art There are two types of rotary transformer cores mounted on a head cylinder of a video tape recorder, such as a flat plate type and a cylindrical type. The latter rotary transformer core is made by cutting a sintered ferrite core into an inner core and an outer core. Regarding their dimensional accuracy, the outer diameter, inner diameter, and groove width are required to be within ± 20 μm. On the other hand, the ferrite used in these members is generally iron oxide, nickel oxide, zinc oxide with copper oxide added, mixed, calcined, added with an appropriate binder, and then granulated, using a metal mold It is manufactured by press-forming into the shape of and then sintering.

However, the workability and other characteristics of the ferrite processed to the above dimensional accuracy must be taken into consideration. Sintered density in ferrite is 99%
If it is above, the core strength is good, but since it is hard when cutting is performed, it is necessary to reduce the feed speed of the cutting grindstone and take care not to crack the ferrite, so workability is poor. It is conceivable to reduce the sintered density of ferrite in order to improve the workability.

[0004]

However, in the above conventional structure, the sintering temperature must be kept below ± 2 ° C. in order to control the ferrite to a predetermined sintering density, so that it is very difficult to manufacture. It was Therefore, there is a problem that even if an attempt is made to produce the same sintered density, the sintered density varies from lot to lot.

The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a method for producing ferrite which can easily reduce the variation in the sintered density of the ferrite from lot to lot.

[0006]

In order to achieve this object, a first calcined product obtained by calcining a raw material containing iron oxide, nickel oxide, zinc oxide, and copper oxide at 1100 ± 50 ° C. and its raw material are used. A second calcined product calcined at 850 ± 50 ° C. was mixed and sintered.

[0007]

With this configuration, the porosity (sintering density) can be controlled by mixing the calcined product, not by controlling the sintering temperature.

[0008]

EXAMPLE A method for producing ferrite in one example of the present invention will be described below.

First, 46 to 51 mol% of iron oxide (Fe ₂ O ₃ etc.), 11 to 16 mol% of nickel oxide (NiO etc.), 28 to 34 mol% of zinc oxide (ZnO etc.) and copper oxide (CuO).
Etc.) 3 to 12 mol% and blended. In this embodiment, the above composition was combined to make 100 mol%, but the effect is not changed even if some other composition (impurities etc.) is contained in addition to this composition. Divide the mixed raw materials into two groups of about half each, and set each group at 1100 ± 50 ℃ and 8
The first calcinated product (1
100 ± 50 ° C) and second calcined product (850 ± 50 ° C)
Was produced.

The reasons for setting the above two calcination temperatures are as follows.
It will be described below. Calcination at 1150 ° C or higher for 20 minutes or longer
Or ZnO sublimation may occur, the composition of Zn at the time of main firing
Deviation occurs about -0.5 to -2.0 mol%, and
And the hardness of the pellet after calcination is
Curse hardness 700kg / mm ²It was over
In comparison with pellets that were calcinated at a crushing time of 1100 ° C
More than 3 times to reach mill grinding (20μm or less)
It is not preferable because it takes time. The calcination temperature is 105
If the temperature is 0 ° C or lower, perform milling (20 μm or less) and
When sintered at 1120 ± 15 ° C, the density is 98% or less.
It will be on the top and the purpose of leaving holes cannot be achieved.

The reason for setting the calcination temperature on the low temperature side to 850 ± 50 ° C. is that if the calcination temperature is less than 800 ° C., the spinelization, which is the crystal structure of ferrite, does not proceed completely after calcination. Was done. Therefore, when molding is performed using a calcined product that does not have a spinel structure, shrinkage of more than 20% occurs during main firing, and the crack generation rate increases. In addition, if calcination is performed at 900 ° C. or higher, the temperature during the main calcination must be increased, which is not economical and shortens the life of the furnace.

Five samples were prepared by mixing the first and second calcined products produced as described above in the following weight ratios.

Sample A First Calcinated Product: Second Calcinated Product = 1: 1 Sample B First Calcinated Product: Second Calcinated Product = 1: 2 Sample C First Calcinated Product: Second Calcinated Product = 1: 3 Sample D 1st calcination product: 2nd calcination product = 1: 4 Sample E 1st calcination product: 2nd calcination product = 1: 5 These samples were wet-milled with a ball mill to 1
Apply for 6 hours, organic binder (polyvinyl alcohol, etc.)
Is added, and dried by a method such as a spray dryer to 98% or more to granulate. At this time, the particle size of this dried product is 80μ.
It is m-200 micrometers. And this dried product is 1120 ±
Firing was performed at 10 ° C. As a result, ferrite having the following porosity could be produced in each sample.

Sample A Porosity 10 to 13% Sample B Porosity 8 to 12% Sample C Porosity 6 to 7% Sample D Porosity 4 to 5% Sample E Porosity 1 to 3% where It should be noted that the same porosity as above can be obtained even if the firing temperature varies by ± 10 ° C. In the conventional manufacturing method, a predetermined porosity cannot be obtained unless the firing temperature is controlled within ± 2 ° C. However, according to the manufacturing method of this embodiment, even if the firing temperature varies to some extent, The porosity of can be obtained. Further, as a result of the experiment, the same porosity can be obtained even if the firing temperature has a variation of ± 30 ° C.

Next, various characteristics of the above sample are shown in (Table 1).

[0016]

[Table 1]

As can be seen from this (Table 1), in the ferrite manufacturing method of this embodiment, the porosity can be easily controlled and the other characteristics thereof are not deteriorated.

[0018]

According to the present invention, a first calcined product obtained by calcining a raw material containing iron oxide, nickel oxide, zinc oxide and copper oxide at 1100 ± 50 ° C. and the raw material is calcined at 850 ± 50 ° C. By mixing and sintering the second calcined product, the porosity (sintering density) can be controlled not by the sintering temperature but by the mixing of the calcined product. It is possible to reduce the variation in the sintering density of.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location H01F 41/02 D 8019-5E (72) Inventor Yoshio Onaka 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Denki Sangyo Co., Ltd.

Claims (4)

[Claims] 1. A first calcined product obtained by calcining a raw material containing iron oxide, nickel oxide, zinc oxide, and copper oxide at 1100 ± 50 ° C., and a second calcined substance obtained by calcining the raw material at 850 ± 50 ° C. A method for producing a ferrite, characterized in that the fired product is mixed and sintered. 2. Iron oxide of 46 to 51 mol%, nickel oxide of 11 to 16 mol%, zinc oxide of 28 to 34 mol%, and copper oxide of 3 to 12 mol%, which are 100 mol% in total. The method for producing a ferrite according to claim 1, which is characterized in that. 3. The ratio of the first calcined product to the second calcined product is 1:
The method for producing a ferrite according to claim 2, wherein the ferrite is 1 to 5. 4. The method for producing a ferrite according to claim 3, wherein the sintered density is 90% to 99%.