JPS59203771A - 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 structural materials constituting various magnetic heads, particularly floppy disk heads.

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

This non-magnetic material for the magnetic head always slides on 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 nonmagnetic material, reducing the functionality of the magnetic head. 3 on the surface of the trench material
If there is an r-id of 0μ or more, this may cause minute chips to occur from the void portion and cause scratches on the surface of the magnetic storage medium.

Furthermore, since these components are processed into the magnetic head through precision machining processes, appropriate workability is required during two-machining processes.

Alumina, forsterite, steatite, etc. cannot satisfy these requirements.

Recently, for heads using N-zn ferrite, B, a material known as a microwave dielectric material, has been used.
It has become common to use a0-TiO2-ZrO2-based porcelain. This is +BaO'r+02-Zr
O2-based porcelain has appropriate workability and wear resistance, and by adjusting the composition ratio, it can be improved to 90 to 100 without impairing mechanical properties.
This is based on the discovery that the coefficient of thermal expansion can be freely changed within the range of X 10-7/°C.

However, as the performance of floppy disk devices has improved in recent years, the requirements for magnetic head materials have become increasingly strict, and the required value for the polished surface has increased to 5.
Below μ is becoming the standard. Ba0 for this request
-TtC)2ZrO2-based porcelain can no longer be manufactured using normal manufacturing methods, and hot press or hot isostatic press (HIP)
) is used. These high-density techniques have made it possible to reduce the voids on the polished surface to a certain extent to meet the required performance, but the high price has prevented widespread use.

The purpose of the present invention is to reduce the voids on the polished surface to 5μ or less despite the normal sintering method, and to have a coefficient of thermal expansion of 90 to 100×l0-7/
℃ BaOT r 02-Z ro2 type non-magnetic ceramic composition for magnetic heads.

The present invention includes TiO280-91.0 mot%, Ba
O6~] 6. Omob%, ZrO20.5~3.0m
ot%, k120. ．． 0.05-1. Omot%.

Y2O30,05~1. The total is 1 from the component range of Omot%, and the thermal expansion coefficient is 9 with a composition of OOmot%.
This is a non-magnetic ceramic composition for a magnetic head, characterized in that the temperature is in the range of 0x10-'°C to 100x10-7/°C.

In the Ba0-TiO system, the mat ratio of TIO2 is 80
In the composition range of mol% or more, the crystal phase of BaT O and T IO
Although it can be predicted from the usual phase equilibrium diagram that B a 2 T l 9020 consists of two crystal phases of 2, detailed research on microwave dielectrics confirmed the existence of B a 2 T l 9020 as a third crystal phase. Furthermore, it is known that the greater the amount of this crystalline phase contained, the greater the strength of the porcelain. Although the amount of Ba2TI 9020 crystal phase produced differs depending on the calcination and sintering conditions, Z(a)2゜S as an additive
It has been recognized that inclusion of nO2 can promote the formation of the Ba2Ti902o crystal phase, and this improves dielectric properties, so BaOTlO2ZrO2 ceramics have been used as dielectric materials for microwaves.

Bao-T i 0 as a structural material for magnetic heads
When looking at 2-Z ro2 type porcelain, Ba2TI, 02
The increase in mechanical strength due to the formation of o is advantageous for applications. In addition, by changing the ratio of BaO and T + '02, the crystal phase of Ba 2T I q O20 and Ti
It has the advantage that the ratio of the O2 crystal phase can be controlled and the coefficient of thermal expansion can be controlled by the volume ratio of both.

from these things.

Bao TiO2-ZrO2-based porcelain has come to be commonly used as a structural material for magnetic heads.

The blending ratio of T r 02 and BaO in the present invention is essential for controlling the thermal expansion coefficient between 90X]O/°C and 100xl-0/°C.

Z ro 2 is Ba2T I 90 as explained above
This is a substance that promotes the formation of 20 crystal phases. Z
This effect was not observed when the amount of rO2 was less than +0.5 mot%.

If it exceeds 3 mot%, the inside of the sintered body is likely to be reduced during the sintering process.

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 after pulverization. That is, as the crushing progresses,
The sintered density is improved and the voids on the polished surface are smaller and less numerous. In order to obtain a sintered body with small voids, the key is how efficiently the pulverization after calcination can be carried out.

One countermeasure is to reduce the calcination temperature as much as possible and grind it into a soft powder, but if calcination is performed at too low a temperature, the raw material barium carbonate (BaC03) may not be sufficiently decomposed. Gas (CO2) to be observed inside the sintered body
), a huge void is generated and has the opposite effect.

As a result of trying various additives to the BaO'r+02 ZrO2 system, the inventor found that A/=,,03. It has been found that the addition of Y2O3 suppresses the reaction during calcination, and a soft calcined powder can be obtained even under calcination conditions in which BaCOx is sufficiently decomposed. Furthermore, the voids in the polished surface of the porcelain obtained by molding and sintering the powder obtained by wet re-grinding are removed by conventional Bao T
It has been found that the size and number of particles are significantly smaller than that of porcelain obtained by the same calcining, crushing, and sintering process using the r 02-ZrO2 system.

fi, t203. The amount of Y2O3 added is 00 in both cases.
The reason for limiting the amount from 5 to 1.0 is that if the amount added is less than this, the effect will be lost, and if it is more than this, the inside of the porcelain will easily form rings during the sintering process, and the material will become hard and difficult to work with. This is because it has been recognized that the deterioration of

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

For T +021 BaCO3 and Z r02, use reagents with a purity level of 99 or higher.

The purity of At203 and Y2O3 as additives is 9.
9% or more of reagent was used. The raw materials were blended so as to have the composition shown in the table, and wet-mixed using a galmill. After drying, crush
Calcining was performed for 3 hours between 1100°C and 1200°C.

The calcined powder was pulverized for 20 hours or more using a resin ball mill. Next, after drying, mix the binder.

10-2. It was molded at a pressure of Ot/cJ. Sintering is 128
The test was carried out in the atmosphere between 0°C and 1360°C. The density and coefficient of thermal expansion of the obtained sample were measured, and voids on the polished surface were observed using a metallurgical microscope. The results are shown in the table.

Blank space below (7) Experimental test strips 1 to 27 are ZnO2, At203. These are sample groups with different amounts of Y2O3.

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

Nonmagnetic ceramics for magnetic heads using NlZn ferrite are required to have a coefficient of thermal expansion of 90 to 100 x 10-7/°C. Samples that can satisfy this are &1 to 25, and the blending ratios of TlO2 and BaO are 80 to 9, respectively]
,, Omo1%, 6-16.0mo7%.

The effect of ZrO2 improves the sinterability of porcelain, and the mechanical strength is improved. It also has the effect of preventing reduction.

This effect was observed up to at least 0.5 mot%.

On the other hand, if the amount of ZnO2 exceeds 3 mol %, the reduction will occur and the voids on the polished surface will become larger. Sample planes 1.11 and 16.21 have excessive Z r O2, so the mechanical strength of the porcelain is weak and the voids on the polished surface are large.
5, 10, 15, 20.25 are Z r O2
In this case, the inside of the sintered body is partially reduced,
The color turns gray, which is not practical.

At203 is effective in preventing grain growth during sintering and obtaining a dense sintered body. The effect was observed at 0.05 moA% or more. If it exceeds +1.0 mo7%, the porcelain becomes hard and brittle and has poor workability. Also BaO and T
Depending on the ratio of r02, reduction may be possible.

Y2O3 has the effect of suppressing reactions during calcination, facilitating pulverization of calcined powder, and narrowing voids in the sintered body. Its effect is 0
．． 05mo/:% or more. On the other hand, the content of Y2O3 increases and 1. , when Omot% is exceeded, At2o
Similar to 3, it hardens the material and deteriorates workability. 4゜9.
14, 19.24 is At203. This is an example in which either Y2O3 is in excess, and the workability is poor.

As is clear from the description of the above examples, 1. According to the present invention, a non-magnetic porcelain composition having a thermal expansion coefficient in the range of 90 to 100 x 10-7/°C, and 2. can be obtained, which is suitable as a non-magnetic structural material for magnetic heads.

Claims (1)

[Claims] 1. TiO280-91.0mol%, BaO6-16
．． 0 mol%, ZrO20.5-3.0 mol%, Al
2O30.05~1.0mol%, Y2O30.05~
The total amount from the component range of 1.0 mot% is 100m
1. A non-magnetic ceramic composition for a magnetic head, characterized in that the composition is made of a composition having a concentration of 0.1%.