JPS6172682A - Zirconia substrate 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 (Field of Industrial Application) The present invention relates to a non-magnetic substrate material suitable for forming a magnetic thin film used in vertical floppy heads and the like.

(Prior art) In recent years, there has been a strong demand for higher recording densities in the field of magnetic recording. Due to the limitations of the magnetic recording system, the perpendicular magnetic recording system is attracting attention as an alternative.

As recording media for perpendicular magnetic recording, coating type hexagonal 13a ferrite with large C-axis anisotropy, and thin film type GO-
Or magnetic films are seen as promising and are being developed.

On the other hand, since conventional magnetic heads formed from ferrite cores are not compatible with magnetic heads, development of magnetic heads with new configurations is underway. For vertical floppy heads, those using a co-Nb-Zr material as the core are considered promising. This is Go-Zr
By adding Nb, the saturation magnetic flux density decreases, but the magnetic permeability increases, so the magnetic properties are improved in a comprehensive sense, but currently sputtering on non-magnetic substrates such as glass by Co-Nb-Z
A method has been invented and put into practical use in which r fJ is formed into a film and a gap portion is formed by bonding. Furthermore, since the Go-Nb-Zr film alone lacks magnetic flux density, ferrite is often used as a backup material, but in any case, a non-magnetic substrate must be used on the surface facing the floppy disk surface. do not have. however,
Currently used glasses have problems in terms of wear resistance or sliding properties. Therefore, a new non-magnetic substrate other than glass is required.

(Problems to be Solved by the Invention) As mentioned above, in the case of a non-magnetic substrate for a vertical floppy head, since a Co-Nb-Zrll film is directly formed thereon, it is necessary to satisfy the following characteristics. be.

First, the coefficient of thermal expansion is Go -Nb-Zr II! It is necessary that the temperature is equivalent to 100'XIO°C of J. If the difference in thermal expansion coefficient between the substrate material and the thin film is too large, problems such as peeling and cracking of the film occur during cooling after film formation. Therefore, the difference in thermal expansion coefficient is at most ±10xi
o'°C-', preferably ±5X10-7°C-'.

Second, since the film is directly deposited, the surface condition of the substrate is extremely sensitive.
Therefore, it is desirable that the bore size be within 1% at most, and that the surface roughness and minute waviness be as small as possible.

Thirdly, do not damage the floppy disk during sliding.
In other words, good sliding properties are required.

Fourthly, good workability is required when processing into a head shape.

An object of the present invention is to provide a ceramic substrate for a magnetic head that satisfies the above-mentioned required characteristics for the substrate.

(Means for Solving the Problems) In order to achieve the above object, the present invention contains 10 to 30 Wj% of yttrium oxide and 0.5 to 1% of aluminum oxide.
0wt%, Mn 02 , Tf 02 , Si
This is a zirconia substrate for a magnetic head, characterized in that it contains 0.2 to 10 wt% of at least one of 02R and l"e20s, and the remainder is substantially zirconium oxide.

The present invention uses stabilized zirconia as a substrate material, thereby achieving the above-mentioned first aspect. This was achieved by discovering that the third required characteristic is satisfied. That is, the thermal expansion coefficient of zirconium oxide (Zr 02 ) varies somewhat depending on yttrium oxide (Y203 ) ffi, but it is 95 to 100×10'°C, and Qo -Nb
-The adhesion when the Zr film is formed is very good.

Moreover, Zr 02 is other aluminum oxide (Al 20
It has extremely superior sliding properties compared to ceramics such as 3), and also has good wear resistance.

As is well known, Zr 02 has two existing uses. One is to add a small amount of ffi+ to fine zrO2 powder.
7) MgO, CaO, Y203, etc. (partially stabilized zirconia that adds a D stabilizer to allow the high temperature layer of the square product to remain up to V temperature and obtains high strength and toughness through stress-induced transformation) The other type is stabilized zirconia, which is used in oxygen sensors that utilize oxygen ion conductivity at high temperatures by adding a large amount of stabilizer.In this way, depending on the amount of stabilizer, the Properties vary greatly.

In partially stabilized ZrO2, the crystal grains are fine and high density products can be easily obtained, but on the other hand, the resistance during cutting is too large, which violates the fourth requirement of good workability as a substrate material. It's inappropriate. On the other hand, the workability of stabilized zirconia, which is mainly composed of cubic crystals, is significantly improved compared to partially stabilized zirconia, but cubic crystals tend to cause grain growth and leave bores inside the grains, so high-density products cannot be used. The disadvantage is that it is difficult to obtain.

In the present invention, stabilized zirconia contains MnO2°T;
02. s;02. Adding sintering aids such as Fe2O3,
Moreover, by using hot isostatic pressing (T11P) treatment after pressureless sintering, it was possible to achieve a high density with a relative density of 99% or more. That is, all of these oxides form a solid solution in ZrO2 and promote sintering of ZrO2, so they are effective in increasing the density.

On the other hand, since the addition of the above-mentioned oxide promotes grain growth, there is a possibility that large bores that cannot be eliminated remain within the grains. Therefore, in the present invention, Al2O which does not form a solid solution with Zr02 is used.
3 is added, and its dispersion suppresses grain growth of cubic ZrO2. In this way, in the present invention, by using Al2O3 and a sintering aid in combination, the effects of both promoting sintering and suppressing grain growth can be seen, so even pressureless sintering alone can achieve a sintered density of about 96 to 97%. Solids are obtained. By further HIPing this, a relative density of 99% or more was achieved.

Furthermore, in the present invention, in order to obtain desired effects, it is necessary to select the composition, sintering conditions, etc. within predetermined ranges, as described below. It is preferable that the amount of Y20a added as a stabilizer is 10 to 30 Wj%. The reason for this is that if the amount of Y203 is less than i owt%, residual square pieces will be present, resulting in a large cutting force. %, it becomes difficult to increase the sintered density, and Y42r3012 and the like precipitate in the cubic crystals, which adversely affects the sliding properties.

The amount of Al2O3 added is preferably 0.5 to 10 wt%.

This is because if it is less than o, swt%, it will not be dispersed in zrO2 and have no effect of suppressing crystal grain growth.
%, the hardness increases and the sliding properties of Zr 02 are impaired. MnO2゜Ti 02
,S! The amount of sintering aids such as 02 and Fe 203 needs to be limited to 0.2 to 10 wt%. This is 0.
This is because if it is less than 2 wt%, there is no effect of improving sintering density as an auxiliary agent, and if it exceeds 10 wt%, contrary to the case of Al2O3, the hardness of Zr02 is reduced. In addition, in the present invention, when the addition amount of Al2O3 and sintering aid is large, the thermal expansion coefficient decreases to below 95X10'°C-', which is the objective range of the present invention of 100±5X10''7°C-/. Therefore, it is inappropriate to add too much.The sintering conditions are 130 °C in the atmosphere.
Firing at 0 to 1600°C is desirable. This is because below 1300°C, sintering is insufficient and the density cannot be increased, and above 1600°C grain growth cannot be suppressed even if Al2O3 is contained. In addition, HIP conditions are 1200~1500℃, 1ooo~150℃
Zero atmospheric pressure is desirable.

In addition, the zirconia ceramic in the present invention contains a total of 2 impurities such as MfJ O, Hf O□, and CaO.
Even if the content is less than wt%, the effects of the present invention will not be diminished in any way.

In the present invention, in order to stabilize Zr 02, Y2
O3 is added, but the addition method is Zr 02
, Y20a powder may be mixed and directly sintered, or a powder co-precipitated from a solution state and calcined may be used.

(Example) The zirconia substrate for a magnetic head of the present invention will be described in more detail with reference to Examples.

Y20 to fine Zr02 powder with a secondary particle size of 0.5μm
3. AI 203, MnO2゜Ti as sintering aid
02. Si02. Fe2O3 was blended in the proportion shown in the table and mixed in a ball mill using ethanol as a solvent. In addition, polyvinyl alcohol (PVA) is used as a binder.
Polyethylene glycol (PEG) was added, and the mixture was granulated by spray drying at 7-degrees, and after molding, it was sintered under the conditions shown in Table 1. After measuring the thickness using the underwater displacement method, it was made into a 3" wafer by surface grinding and mirror lapping. After measuring the surface roughness,
Form a film of o-Nb-ZrI% by sputtering,
The adhesion of the membrane was evaluated. In addition, cutting resistance was measured by measuring the stress applied to the blade of a peripheral slicer using a piezoelectric element. The above results are shown in Table 2.

No. in the table, 1.5, 6.9.10, 13, 14゜17
is a comparative example outside the scope of the present invention.

In Table 2 No. 1 to 5, AI 2035wt%, TiO25w
This is a case where t% of Y2O3 is added and the amount of Y2O3 is changed.

N001, which has a low Y203 ffi, has a relative density that is close to almost the theoretical density and a fine crystal grain size, but the cutting resistance is significantly greater than in other cases, making it unsuitable as a substrate material. If the Y2O3 suspension is increased, the cutting resistance will decrease, but if it is too high, as in N005, the density will decrease rapidly.

No. 6 to 9 are Y2O315wt%, TiQ25wt%
was added to change the Al 203fl.

When A1203ffi is small like No. 6, the crystal grain size is as large as 15 to 20 μm, whereas as Al2O3 is increased, the crystal grain becomes finer and chipping during cutting becomes smaller. However, if the amount is too large, the thermal expansion coefficient becomes small and the adhesion of the film deteriorates.

No. 10 to 13 are Y 20315wt%, Al203
TiQ2fi was changed by adding 5 wt%. T! If 02ffi is small, sufficient sintered density cannot be obtained. As Ti021 increases, sufficient density and hardness decrease.

Nos. 14 to 17 are cases where the sintering temperature was changed.

At 1200°C, the density is as low as 95%; at 1300°C, it becomes sufficiently dense to the extent required for -IIP, but
At temperatures above 0°C, grain growth of crystal grains cannot be suppressed even if Al2O3 is added.

In Nos. 18 to 21, MnO2゜Si02, Fe203, etc. were added instead of T + 02, but although there were differences in grain size and color of the sintered bodies, sufficient density was obtained in all cases. It was done.

(Effects of the Invention) As described above, the zirconia substrate of the present invention has excellent sliding properties, high density, workability, etc., and is a suitable material for a substrate for a vertical floppy head.

Agent Patent attorney Taka Ishi Tachibana Indication of the Ma case 1982 Patent application No. 192356 Title of the invention Relationship to the case involving a person who corrects zirconia substrates for magnetic heads Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (s
og) Norio Kono, Representative of Hitachi Metals, Ltd.

Claims (3)

[Claims] (1) Yttrium oxide 10-30wt%, aluminum oxide 0.5-10wt%, MnO_2, TiO_
2. A zirconia substrate for a magnetic head, comprising 0.2 to 10 wt% of at least one of SiO_2 and Fe_2O_3, with the remainder being substantially zirconium oxide. (2) Thermal expansion coefficient is 95 to 105 x 10^-^7℃^-
The zirconia substrate for a magnetic head according to claim 1, wherein the zirconia substrate is ^1. (3) The zirconia substrate for a magnetic head according to claim 1 or 2, which has a density of 99% or more of the theoretical density.