JPS6110052A - Substrate material for thin membrane 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 material for a non-magnetic substrate used in a slider of a magnetic head used in data processing technology, particularly in the field of magnetic disk files.

(Prior Art) As a magnetic head used for a magnetic disk, one having a structure as shown in, for example, Japanese Patent Publication No. 57-569 is often used. In such a floating head, a magnetic core made of a magnetic material with high magnetic permeability is fixed to the rear end of a slider made of a non-magnetic substrate or a magnetic substrate. On the lower surface side of the slider, the magnetic core has a magnetic transducer gap, and the magnetic core is provided with an electromagnetic transducer winding to constitute a magnetic transducer. A floating magnetic head with such a configuration lightly contacts the magnetic disk due to the force of a spring when the magnetic disk is stationary. When the magnetic disk is rotating, the air near the surface of the magnetic disk similarly moves and flows to lift the bottom surface of the slider of the magnetic head.

A part of the magnetic transducer of the magnetic head is M-Zn
It is often made of ferrite or rough 1-ferrite such as 1qizn ferrite. However, when increasing the recording density of a magnetic disk, it is required to reduce the width of the magnetic core and the length of the magnetic conversion groove. In this case, a magnetic thin film made by sputtering or the like, such as a permalloy thin film or an amorphous metal thin film, is used as the magnetic core. Also, one magnetic core is made of soft ferrite and the other core is made of a magnetic thin film. If a thin film core is used, a thin film of an insulating material such as Al2O3 may be provided in common to the magnetic thin film and the slider to obtain electrical insulation between the electromagnetic conversion winding and the magnetic PTS film and between the electromagnetic conversion winding. be. In addition, if the non-magnetic substrate slider is made of a material with relatively low electrical resistance, a thin film of an insulating material is attached to the slider surface to insulate the Va thin film on the slider, and a magnetic A transducer may also be formed.

This kind of magnetic head does not come into contact with the magnetic disk because it is suspended by air flow while the magnetic disk is rotating, but when the magnetic disk starts rotating and stops rotating, the magnetic head Contact with the disc surface. The contact situation when stopping the rotation of the magnetic disk is such that as the rotation of the magnetic disk slows down, the flow of air on its surface gradually slows down. In this way, when the buoyancy of the magnetic head is lost, the magnetic head hits the surface of the magnetic disk. The reaction causes the magnetic head to fly up and fall back onto the disk surface. After repeating this motion several times, the magnetic head begins to be dragged along the magnetic disk, and finally stops. The magnetic head must withstand such shocks when starting and stopping, and its performance is determined by C8S characteristics (Content
act-8tart-8top).

In order to improve C8S performance, it is important that a portion of the slider of the magnetic head has excellent sliding properties. Furthermore, the surface of the slider should be flat and free of pores. It is necessary to have good wear resistance.

The structure of a part of the slider of a magnetic head is as shown in Japanese Patent Publication No. 55-163665, for example.
It has an extremely complex structure. In order to manufacture a magnetic head having such a structure with good productivity, it is necessary to have good machinability. It is required to have low cutting resistance during machining and to avoid clogging of the cutting blade.

Also, during machining, crystal grains in the processed area may fall off, but it is desirable that the size of these fallen areas be small.

To this end, it is desirable that the crystal grains of the material constituting the slider be small.

The above-mentioned magnetic head is described in Japanese Patent Application Laid-Open No. 55-551
No. 63665. The slider of the magnetic head shown in A is made of a mixture of Al2O3 and TiC, and the weight ratio of Al2O3 and TiC is 60:40 to 80.
: In the range of 20.

Al2O3TIC ceramics have good workability and do not cause cracks or chipping when processed into complex shapes. It also has excellent wear resistance. However, when this ceramic is used as a slider for a magnetic head, it is inferior in C8S properties, particularly in sliding properties, which is the most important performance.

Since Al20a TiC ceramics have poor sliding properties as described above, it was proposed in Japanese Patent Publication No. 58-166562 to remove TiC particles on the slider surface by reactive ion sputtering. However, after removing TiC by reactive ion sputtering, a bore several nanoliters deep was created, and after long use, A
C8S properties sometimes deteriorated due to lack of l20a particles.

On the other hand, it has been reported in Japanese Patent Application Laid-Open No. 57-100976 that Al 2032r 02 -based t-1:''/cus has high bending strength and strong toughness suitable for use in tools by containing tetragonal zirconia inside. number or rung (F, F
, Lan1+e) and the Journal of Materials Science (J
Our own of MaterialsSc
17 (1982) 247-254. However, when such strong ceramics are used for the slider, the workability is poor and complicated processing becomes difficult.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide a substrate material for a thin film magnetic head used in a slider etc. that has excellent sliding characteristics.

Furthermore, according to the substrate material of the present invention, machinability is also improved.

(Means for Solving the Problems) Therefore, the magnetic head substrate material of the present invention is characterized by using alumina-zirconia ceramics with good sliding properties.

The alumina-zirconia ceramic of the present invention contains 5 to 70 SO1% of zirconium oxide that substantially has a cubic crystal structure with good sliding properties, and the remainder is substantially aluminum oxide. In order to make the zirconium oxide substantially cubic structure, the zirconium oxide is Y203,
Dy 203. At least one species of Yb 203 is
It is desirable to contain 5 to 20 mo1%, preferably 8 to 12 mo1%, based on 021k.

When the zirconium oxide in the aluminum oxide is less than 5m01%, the tetragonal zirconia is more than 5%,
Since there is little cubic zirconia with good sliding properties, the sliding properties are poor. Further, the effect of grain refinement due to the composite of two types of ceramics is lost. Further, when the amount of zirconium oxide exceeds 70 mo1%, the number of pores in the ceramic increases, and the relative density is low even after HIP. Further, although cubic zirconia generally tends to cause grain growth, when the amount of zirconium oxide is large as compared to alumina, the crystal grains become large.

Therefore, when the amount of zirconium oxide is in the range of 5 to 70 mo1%, the effect of refining crystal grains due to compounding is large.
The crystal grain size is 2 μm or less, and there is little chipping. In particular, at around 20 mo1%, the particle size becomes the minimum and chipping also becomes the least.

Alumina-zirconia ceramics usually contain trace amounts of impurities. As an impurity, S! 0
2, Ca o, Hf 02 and MQ O are 21 in total.
It may be contained in an amount of 101% or less.

The alumina-zirconia ceramic phase contains enough stabilizer to exist as cubic zirconia even at room temperature. Y203, Dy2Oa, Yb
In the case of 20a, there are 5 to 20 so1 in the zirconia phase.
%, and the remainder is preferably Zr 02. However, there is no problem even if MgO and CaO are also contained at the same time.

If such a stabilizer is included in excess, for example, Y2
In the O3 case, Y4 Z is present in the cubic zirconia.
Compounds of Zr 02-Y20a such as ra 012 precipitate, leading to deterioration of sliding properties and reduction of strength. 20101% or more Y2O3, DV20a, Yl)2
It is undesirable to contain 0a.

When the amount of stabilizer decreases, more than 5% of zirconia becomes tetragonal, which changes to monoclinic due to glH on the substrate and heating and cooling to several hundred degrees Celsius during patterning. There is a risk that the substrate may warp or be misaligned due to volumetric expansion. Therefore, the lower limit of the stabilizer to produce stabilized zirconia is approximately 5 mo 1%. 'I'
The content m of 203 is preferably as small as 5Ilo1% or more, and a more suitable amount is about 8 to about 12 mo1%. In addition, it is a tetragonal crystal.

The density of cubic zirconia can be measured by X-ray diffraction. When the content of 8I is 01% or more, zirconia becomes completely cubic, and when the content is more than 12 mo1%, the sinterability becomes poor.

Furthermore, it is desirable that the relative density (compared to the theoretical density) of the substrate material used in the magnetic head of the present invention is 99% or more, and the number of bores is extremely small. Since it has such a high density, it has excellent sliding properties.

In the magnetic head substrate material of the present invention, it is not necessary to provide an insulating film such as an Al2O3 thin film between the alumina slider and the magnetic transducer. Since alumina-zirconia ceramics has almost the same electrical resistance as Al2O3 (10/d to 10'3 Ω·Cll1), there is no need to attach an insulating film.

Luniha, which manufactures the alumina-zirconia ceramics of the present invention, Zr 02 fine powder, Y2O3, Dy2O3, Yb
Blending 2O3 powder and A120a powder in a predetermined ratio,
Mix thoroughly, dry, add a small amount of binder, and granulate. This granulated powder is preformed into a molded body using a press having a key of the desired shape. After firing this molded body in the air at a temperature of 1400°C to 1600°C to a relative density of about 98%,
HIP at 0°C to obtain 99% or more alumina-zirconia ceramics.

The temperature at which this HIP (Hot Isostatic Press) is performed determines the performance of the obtained alumina-zirconia ceramics. A temperature of 1300° C. or higher is necessary to increase the relative density of ceramics to 99% or higher. However, if the temperature is higher than 1500℃, the grain growth of stabilized zirconia grains will become significant, so if the temperature is lower than 1500℃, HI
It is desirable to do P.

As mentioned above, alumina-zirconia ceramics are always used! ■It is suitable for mass production because it can be made by 1-111) after sintering, but it can also be made by hot pressing.

The alumina-zirconia ceramic thus obtained is cut into the shape of a magnetic head slider using a diamond blade, and then finished using a grinder or the like. A magnetic core and signal coil are attached to a slider-shaped object to create a magnetic head.

(Effects of the Invention) As explained above, since the substrate material for a thin film magnetic head of the present invention uses alumina-zirconia ceramic as its nonmagnetic substrate, it has excellent slidability with a magnetic disk and wear resistance. Cubic zirconia is soft and has good sliding properties. Also, since it has a high density and almost no bore, C8
S performance is high.

Furthermore, since the crystal grains are extremely small, there is almost no chipping, and the machinability is good, fine processing can be performed.

(Example) Regarding the alumina-zirconia ceramics of the present invention,
An example is shown below.

Example Al2O3 powder, ZrO2 fine powder with an average particle size of 0.03 μs, and Y203. DY 20a powder was blended in the proportion shown in the table and mixed for 24 hours in an alumina ball mill using pure water as a solvent. Dry the mixed solution, add 10% PVA solution, granulate it with a sieve machine, and then 80φ with a pressure of 1 ton/C1.
A molded body of ×G~7 was preformed. 15 in the atmosphere
After firing at 00℃ for 1 hour, it was heated to 1350℃ at 1500 atm.
The density of the sintered body was measured by the underwater replacement method and divided by the theoretical density to obtain the relative density. A part of the sample was polished to a mirror surface.The sample was also viewed under a microscope to measure the average grain size.

The chipping resistance was measured according to the size of chipping that occurs on the edges during grooving with a dicer (indicated by the maximum chipping depth in the table).

The cutting resistance was measured using a piezoelectric element using a peripheral slicer and the stress applied to the slicer.

The sliding characteristics were determined by a C8S test in which a magnetic disk was rotated and an alumina-zirconia ceramic was made to slide in contact with the magnetic disk. In the table, O marks indicate those that withstood 100,000 or more contacts, Δ marks indicate those that withstood 30,000 to 100,000 contacts, and X marks indicate that defects occurred after less than 30,000 contacts. It is. During this measurement, a piezoelectric element made of bimorph was attached to the tip of the ceramic, and the occurrence of defects was measured based on the pressure change.

As is clear from the table, samples No. 011 to No.

Samples up to 13 are alumina-zirconia ceramics, and sample FIN0.14 is alumina-titanium carbide ceramics. This No. 14 is a known one,
The sliding properties were poor compared to alumina-zirconia ceramics, and defects occurred after less than 30,000 cycles of C8S. but,
The alumina-zirconia ceramics withstood more than 30,000 cycles of C8S. Further, samples Nos. 083 to 13 containing 5101% or more of ZrO2 withstood 100,000 times or more of C8S.

The cutting resistance force of sample No. 13 was extremely large. This is because the Y20a content was only 2 mo1%, so a large amount of tetragonal zirconia was produced.

Looking at the grain size and maximum chipping depth, sample No.
It is clear that the values from No. 3 to No. 10 are extremely small.

From this result, it was found that when the amount of ZrO2 was in the range of 5 to 70 mo1%, the crystal grain size and maximum chipping depth were small, and the vibration characteristics were improved.

In addition, the hardness is HV r 1300-1600. Density is also H
More than 99% was obtained by IP.

Claims (1)

[Claims] 1. Substantially cubic zirconium oxide with 5 to 70
A substrate material for a thin film magnetic head made of alumina-zirconia ceramics containing mol% of aluminum oxide and the remainder being substantially aluminum oxide. 2. In claim 1, the alumina-zirconia ceramic has cubic zirconium oxide particles dispersed in an alumina matrix, and these cubic zirconium oxide particles are
A substrate material for a thin film magnetic head, comprising 5 to 20 mol% of at least one of _2O_3, Dy_2O_3, and Yb_2O_3.