JPS59203770A - Non-magnetic ceramic composition for magnetic head - 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 The present invention relates to non-magnetic ceramics necessary for the construction of magnetic heads of floppy disk devices such as electronic computers.

Conventionally, alumina, forsterite, steatite, etc. have been used as nonmagnetic structural materials for magnetic heads. However, these drawbacks are that the composition of the magnetic material ferrite differs depending on the specifications of the magnetic head, so the thermal expansion coefficient changes accordingly, and the thermal expansion coefficients of ferrite and non-magnetic material do not match. Cracks occurred in one of the glass bonding steps, reducing the yield of 9.

This non-magnetic material for the magnetic head always slides along the floppy disk surface at high speed simultaneously with the ferrite. Therefore, if its wear resistance is not on the same level as ferrite, a gap will be created between the ferrite portion and the non-magnetic material, reducing the functionality of the magnetic head. Furthermore, if there are voids of 30 microns or more on the surface of the material, minute chips may occur from the voids, causing scratches on the disk surface of the magnetic storage medium. Furthermore, these components are processed into magnetic heads through a precision machining process.

Appropriate workability is required.

Alumina, forsterite, steatite, etc. cannot satisfy all of these requirements. Therefore, recently, for heads using Mn--Zn ferrite, it has become common to use calcium titanate-based porcelain, which is a known material, as the dielectric material.

Mn-Zn ferrite is a material with a relatively large thermal expansion coefficient for porcelain.9 Although it varies slightly depending on the composition ratio, 1
It has a coefficient of thermal expansion of 05-1.15X10/°C.

Calcium titanate porcelain.

This is because it has been found that it is a non-magnetic porcelain that has a coefficient of thermal expansion that can accommodate this, and has appropriate workability and wear resistance.

As the performance of floppy disk drives has improved in recent years, the requirements for magnetic heads and their materials have become increasingly strict, and a requirement for voids on the polished surface of 5 μm or less is becoming the standard.

In response to this demand, calcium titanate-based porcelain cannot be produced using normal manufacturing methods, so wrinkle hot pressing methods and hot isostatic pressing methods (HIP) have come to be used. By using these methods of increasing the density, it is possible to achieve voids on the polished surface of 5μ or less.

Problems tend to arise with mass production and manufacturing costs9. A wide range of applications are impeded.

The object of the present invention is to provide a non-magnetic ceramic composition for a Cao-T + 02 magnetic head, which can be produced using a conventional sintering method but has voids on the polished surface of 5 μm or less.

The present invention provides TiO249 mo1% to 65 mo1%
+CaO34mo1% ~50 mo1%t Y2O
It has a composition with an ingredient range of 30.05mol% to 2.0mol%, with a total of 100mol%, and a thermal expansion coefficient of 1.0OX10/℃ to 120XiO'/
1? This is a non-magnetic ceramic composition for a magnetic head, characterized in that the composition falls within the range of:

The coefficient of thermal expansion is approximately determined by the ratio of TiO2 and CaO. However, the amount of Y2O6 added is also slightly different5, Y2O3
As the amount of increases, the coefficient of thermal expansion decreases. TiO2 and Ca
The reason why the amount of 0O was selected as above is within the range of these amounts, which corresponds to the coefficient of thermal expansion of Mn-Zn ferrite]
, 0OX10/°C], a coefficient of thermal expansion in the range of 20 x 1.0 7°C is obtained.

The purpose of adding Y2O3 is to reduce the size and size of voids on the polished surface of the sintered body.

The size and amount of voids on the polished surface of the sintered body are inversely proportional to the particle size of the calcined powder. That is, as the grinding progresses, the sintered density improves, and the voids on the polished surface simultaneously become smaller and their number decreases.

In order to obtain a sintered body with small voids, the most important point is how to obtain a pulverized powder after calcining with a small particle size.

The countermeasure is to increase the crushing efficiency. If the calcined powder is softened by lowering the calcining temperature, the grinding efficiency will increase and powder with a smaller particle size can be obtained, but in that case, the raw material calcium carbonate (CaCOs) will not undergo sufficient decomposition reaction. This may cause gas to be generated inside the sintered body, causing huge voids.

As a result of trying various additives to the p-CaO-TiO2 system, the inventor found that the addition of an appropriate amount of Y2O3 suppresses the reaction during calcination, and a soft calcined powder can be obtained even under calcination conditions where CaCOs is sufficiently decomposed and reacted. I found out that it can be done. Furthermore, we investigated the polished surface of the porcelain obtained by wet re-pulverizing the powder, molding and sintering it, and found that it was obtained by the same calcining, crushing and sintering with the conventional CaO-T]02 system. It has been found that the voids are significantly smaller and the number of voids is reduced compared to that of porcelain. Y2O
The lower limit of the addition amount of 3 is 0.05, the upper limit is 2.0 mo1
The reason why it is limited to 0.05% is because the above-mentioned effect cannot be obtained if the amount added is less than 0.05%, and 2.
%, the hardness of the porcelain will increase, the material will become brittle, and its workability will deteriorate.

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

For T1021 CaCO3, a reagent with a purity of 99% or higher was used.

Further, as for Y2O3 as an additive, a reagent with a purity of 99 or higher was used. The raw materials were blended to have the composition shown in the table and wet mixed in a 1 lumen. After drying, pulverize from 1100℃ to 1200℃.
It was calcined for 3 hours at ℃. Is the calcined powder made of resin? - Pulverized for more than 20 hours using Lumil.

Next, after drying, mix the binder and mix the binder. Ot/m
Press molding was performed at a pressure between

Sintering was performed in air between 1280°C and 1340°C. The density and thermal expansion coefficient of the obtained sample were measured, and the roughness of the polished surface was evaluated. The results are shown in the table.

In the margin table below, experimental samples Nα1~5, 6~10°1]~1
5.16-20.21-25 are +Tt02 respectively
This is a group of samples in which the mixing ratio of CaO and CaO is constant, and the amount of Y2O3 added is different.

The coefficient of thermal expansion is approximately determined by the ratio of +TlO2 and CaO.

However, the amount of Y2O3 added is also slightly different; as the amount of Y2O3 increases, the coefficient of thermal expansion decreases.

The thermal expansion coefficient of a non-magnetic porcelain for a magnetic head using Mn-Zn ferrite is 1.0OX10'/℃~120
X10/℃ is required and T r 02 that can satisfy this value
The mixing ratio of CaO and Samples Nα1 to 2o.

Therefore, the blending ratio of TlO2 and CaO is 49, respectively.
It can be seen that 34 to 50 mot% is sufficient for ~65 mot.

On the other hand, in the case of no addition of Y2O3 (sample N11l l 6
F 11. +i-6, 21) and the case of addition (residue sample), it is clear that it improves the voids on the polished surface.

Addition of Y2O3 is effective. The effect is 0.05mo
Even A% is acceptable. Also, the amount of Y2O3 increases and 2
If mo exceeds 1%, the material becomes brittle and has poor workability (Samples Nα5, 10, 15, 20, 25).

As is clear from the above examples, two TiO249~
65motq6. CaO34~50motchi, Y2O5
0.05-2 mot% non-magnetic ceramic composition contains Mn
-Zn has a coefficient of thermal expansion corresponding to that of ferrite, has small voids on the polished surface, and has excellent workability, making it ideal as a nonmagnetic material for magnetic heads.

Claims (1)

[Claims] ], Tie249~65mot%, Ca034
~50motq6゜Y2O3o, 05~2.0mo1
1. A nonmagnetic ceramic composition for a magnetic head, characterized in that the composition has a total of 1,00 mo1% over a range of components.