JPS60171267A - Manufacture of ni-zn ferrite - 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 [Technical Field] The present invention relates to a method for manufacturing high-density ferrite.

[Prior art]

Ferrite is widely used in audio magnetic heads, VTR magnetic heads, computer magnetic heads, etc., but in recent years, with the progress of higher quality and higher density recording, ferrite has high magnetic properties and has been used in heads and There is a growing demand for dense ferrite with good workability and fewer pores that can cause media damage.

Conventional methods for producing high-density ferrite include the rubber press method, hot press method, and hot isostatic press method (hereinafter referred to as HIP method), but these methods have a large pore elimination effect and are difficult to produce. The HIP method has better properties than other methods. In addition, the method of producing high-density ferrite by the above-mentioned HIP method is, for example,
It is known from Japanese Patent Publication No. 558, Japanese Patent Publication No. 5B-14050, etc.

I (The method of producing high-density Ni-Zn ferrite by the IP method is to
After wet-mixing ZnO and ZnO oxides in a ball mill, filtering, and drying, in order to stably proceed with the subsequent molding and primary sintering steps, the mixture was pre-fired at a temperature of 900°C to 1100°C. % or more of the spinel phase. Thereafter, the powder is wet-pulverized for a predetermined time using a ball mill or an attritor to obtain the optimum powder. After further adding a binder, it is molded into a predetermined shape and 1
This is a method for producing dense Ni-Zn ferrite by subjecting the sintered material, which has been sintered and made into a closed pore state, to high-pressure and high-temperature treatment in an Ar gas atmosphere. At present, problems such as internal pores and precipitated ZnO phases remain.

Therefore, in order to produce ferrite that is dense, uniform, small particle size, and has excellent magnetic properties, sufficient consideration must be given not only to the primary sintering and HIP conditions, but also to the previous powder manufacturing process. I had to. In the calcined state of the toms, the particle size, particle size distribution, etc. must be controlled extremely accurately, and the results are not always completely satisfactory.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a manufacturing method that reliably provides Nt--Zn ferrite having a dense, uniform, small grain size and high magnetic properties.

[Structure of the invention]

The method of the present invention improves the relationship between the reactivity of the powder in the pre-firing step, the amount of so-called spinel phase, and the powder properties in the pulverization step, so-called particle size and particle size distribution, in the Ni-Zn ferrite crystal grains with the HIP treatment step. Focusing on the fact that it has a large effect on the structure and magnetic properties, by passing the mixed powder of ferrite raw materials through compression in a roll mill before calcining, a grain structure with a dense and uniform small particle size is obtained. This is how it was done.

That is, according to the present invention, powder raw materials containing iron, nickel, and zinc oxides as main components are mixed, pre-sintered, pulverized, press-molded, sintered, and hot isostatically pressed to produce high-density ferrite. There is obtained a method for producing a Ni--Zn ferrite material, characterized in that a roll mill compression treatment is performed between the mixing treatment and the pre-baking treatment.

〔Example〕

First, the ferrite mixed powder that had been subjected to the roll mill treatment according to the present invention was used as it was, as compared to the conventional one, which was treated at a lower temperature. This ferrite mixed powder was first treated with a ball mill for 40 hours, and then processed with a roll mill for 3 hours.
000 at a pressure of 9/cIl and then subjected to pre-firing treatment. In the conventional case, the material is subjected to pre-firing treatment without performing this compression passage step using a roll mill.

Figure 1 shows the relationship between the pre-firing temperature and the amount of spinel determined by X-ray diffraction when the above-mentioned pre-firing process is carried out for one hour, comparing the manufacturing method of the present invention and the conventional manufacturing method. It is a diagram. As can be easily seen from Figure 1, if the preheating treatment time is set to 1 hour, which is reasonable from a practical point of view, a single spinel set cannot be obtained with the conventional method unless the temperature is 900°C to 1100°C. On the other hand, 9 of the present invention can be obtained at a low temperature of 800°C, so it is extremely effective practically.

This is understood to be because the powder compressed through a roll mill has a large compression strain and easily becomes a single spinel set at low temperatures.

In addition, in the above, the compression pressure of the roll mill is 3 as an example.
000KP/cI/l is used, but of course it is not limited to this and has a considerable vertical width.

However, according to experiments, the compression pressure of the roll mill is 1000
At about KV/d, the amount of spinel obtained is not much different from that obtained by the conventional method, and at 1/d or more, the powder cannot be easily sized by passing through a sieve, which is not preferable. The amount of spin by the above X-ray diffraction is determined by the gamma-ray diffraction angle (
2θ) is the sum of the diffraction intensities of the spinel phase detected in the range of 60° to 90°, and the spinel phase and α-Fe 203
It is determined as a percentage of the total diffraction intensity.

Next, the powder obtained by the above-mentioned pre-calcination treatment is subjected to a subsequent ball mill treatment (second time), and the particle size distribution of the resulting pulverized powder will be explained by comparing the particle size distribution of the present invention and the conventional one. The raw materials used and the first ball milling were the same as in the case of FIG. 1 above. The pre-calcination treatment of the raw material powder was performed at 850°C in the case of the present invention using the results obtained previously.
In the conventional case, the temperature was 1000°C.

This prefired powder was pulverized for 12 hours in a ball mill (second time).

FIG. 2 is a diagram showing the particle size distribution of the pulverized powder obtained in this way.9 The particle size is about 0.6 μm in the conventional case, while it is about 0.2 μm in the case of the present invention. It is small, and the distribution shape is narrow.

The reason why the powder according to the present invention is small is because the temperature of the pre-baking treatment, which is a pre-process, is low in the present invention and the grain growth of the powder is suppressed. A powder with good properties can be obtained.

And when this powder is subjected to the next pressing treatment.

A product having a relative density of 96- or more can be obtained. Furthermore, Ni-Z
Judging from the fact that roll milling of ferrites other than n-based ferrites does not show the same effect as Ni-Zn ferrites, ZnO appears to play a major role.

The two embodiments described above describe the features of the present invention, from Alroll milling to press processing, but the embodiments to be described from now on will be carried out on products that have undergone all steps. In this example, two types of compositions are used as raw materials. One raw material contains 49.5 mo1% of Fe2O3 and 19.0 mo1 of NiO.
It is an oxide powder having a composition of 1% by mole and 31.5% by mole of ZnO.

The other raw materials are oxide powders having a composition of 49.5 mo1% Fe2O3, 17.0 mo1% NiO, and 33.5 mo1% ZnO. Hereinafter, the former will be named composition A, and the latter will be named composition. Exactly the same treatment is then performed on these two raw material powders. In either composition,
-1, Zuko's oxide raw material powder was mixed for 40 hours in a ball mill, filtered and dried, then heated to 3000K in a roll mill.
It passes through compression at a pressure of P/d. Thereafter, it was prefired at a temperature of 800°C for 1 hour in an air atmosphere.

Furthermore, the average particle size was 0.2 μ by milling in a ball mill for several hours.
m of powder was obtained, a binder was added to this powder, and a 60 x 30 x 1 powder was obtained using a press at a pressure of 92000 KV/d.
A green compact of 0wn was prepared, and primary sintering was performed in the air at a temperature of 150°C for 2 hours, followed by HIP treatment for 2 hours at a treatment temperature of 1100°C and a pressure of IOD OK9/crIl+ 7 in an atmosphere of 7. went.

Figure 6 shows the high-density Ni-Zn obtained as described above.
FIG. 2 is a diagram illustrating some properties of ferrite in comparison with articles obtained by a conventional method that does not involve compression passing through a roll mill.

Further, FIG. 4 is a diagram showing a similar comparison of effective magnetic permeability, which is one of the dynamic characteristics.

Points to note in particular in Figure 6 are as follows.

The characteristics of the ferrite obtained by the method of the present invention are as follows.

Compared to conventional products, it has a high specific resistance, a small average particle size and a small porosity, and a large bending strength. Note that the bending strength is high.

When this ferrite is used as a magnetic head.

Combined with its high magnetic properties, it is extremely effective.

Furthermore, it can be seen from FIG.
Since it shows excellent frequency characteristics, the = &B case also improves at almost the same rate. In terms of the characteristics shown in Figure 6, this means that specific resistance, average particle size, and porosity are improved. The powder particle size obtained by ball milling is 0.
This is due to the fact that it is about 2 μm, which is about one-sixth of the conventional size.

[Effects of the Invention] As explained above, according to the present invention, high-density Ni--Zn ferrite having excellent magnetic and mechanical properties can be easily produced, and is extremely useful as a ferrite material for magnetic heads.

Below is the money mouth

[Brief explanation of the drawing]

Figure 1 is a diagram comparing the relationship between the pre-firing temperature of Ni-Zn ferrite and the amount of spinel obtained by this pre-firing between the present invention and the conventional one. Fig. 5 shows a comparison of the particle size distribution of the pulverized powder obtained by the present invention and the conventional one, and Figure 5 shows a comparison of the characteristics of the Ni-Zn ferrite after HIP treatment between the present invention and the conventional one. FIG. 4 is a diagram comparing the effective magnetic permeability, which is one of the characteristics of Ni-Zn ferrite, between the present invention and the conventional one. Figure 1 Bracket 2

Claims (1)

[Claims] 1. A method for producing high-density ferrite by mixing, pre-sintering, pulverizing, press-molding, sintering, and hot isostatically pressing powder raw materials containing iron, nickel, and zinc oxides as main components. , Nr characterized in that a roll mill compression treatment is performed between the mixing treatment and the calcination treatment.
- Method for manufacturing Zn7 elite material.