JPH05109024A - Substrate material for magnetic head - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a substrate material suitable for a magnetic head having excellent sliding characteristics, high strength, high toughness, wear resistance, and low frictional electrification resistance due to a small specific resistance. .. [Structure] Tetragonal Zr with Y ₂ O ₃ or MgO as a solid solution
O ₂ as a main component, TiC 15 to 40 wt% and T
A magnetic head substrate material containing 5 to 20% by weight of at least one of i, Zr, Mo, W, Ta, Nb and Cr silicides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head substrate (slider) material excellent in durability, wear resistance and lubricity.

[0002]

2. Description of the Related Art In recent years, thin film magnetic heads are rapidly becoming popular in order to meet the increasing demand for higher recording density in the field of magnetic disk devices. The thin film magnetic head has a structure in which a thin film element for recording and reproducing a magnetic signal is formed on the rear end surface of a ceramic slider, and the slider generates an air layer generated by a high speed rotation (20 to 40 m / s) of a magnetic disk. It has a function of writing / reading a record to / from a magnetic disk by utilizing the fact that it rides on the flow and slightly floats (0.2 to 4 μm) on the surface of the magnetic disk. Therefore, the slider activates the rotation of the magnetic disk,
Since a sufficient air laminar flow cannot be obtained at the time of stop, it always slides on the magnetic disk to perform a so-called contact start stop (CSS) operation. Further, even if the slider is flying normally, it is inevitable that the flying height and the flying posture are disturbed by external factors such as vibrations and the intervention of dust.

Since the flying height is becoming smaller in order to increase the recording density, the number of times the slider collides with the magnetic disk rotating at high speed due to such turbulence is increasing more and more.

From these things, it is important to improve the slidability of the slider of the magnetic head in order to improve the CSS performance. Furthermore, it is necessary that the surface of the slider is smooth, that there are no pores, and that it has good wear resistance.

Further, as described above, the magnetic head is frictionally charged when it comes into contact with and slides on the magnetic disk. If this charge amount becomes excessively large, noise may occur in the signal winding of the magnetic transducer or the flying height of the magnetic head may change. Therefore, it is desirable to configure the slider of the magnetic head with a material that does not cause frictional charging as much as possible.

Further, the slider of the magnetic head has an extremely complicated structure as disclosed in, for example, Japanese Patent Laid-Open No. 55-163665, and a magnetic head having such a complicated structure can be manufactured with high productivity. Requires that the slider constituent material has excellent machinability. That is, it is important that the cutting resistance during machining is small, that the cutting blade is not clogged, and that cracks and chipping do not occur.

As a conventional slider material, Al ₂ O ₃ based ceramics are widely known from the viewpoint of good thin film element formability, and there are many proposals for improvement. For example, JP-A-61-1588
62, JP-A-60-231308, and JP-A-60-183.
709 and JP-A-60-179923.

All of these are composed of Al ₂ O ₃ --TiC and other added particles, and are intended to improve wear resistance and workability. On the other hand, slider materials containing ZrO ₂ system as a main component are disclosed in, for example, JP-A-60-171617 and JP-A-63-27.
8312, Japanese Patent Laid-Open No. 60-66404, and the like, a slider having good sliding characteristics has been proposed.

[0009]

[Problems to be Solved by the Invention] However, the above A
The slider made of l ₂ O ₃ -TiC has excellent machinability and wear resistance, but when processing a slider with a high precision and complicated shape, cracks and chipping are not small and the processing yield is reduced, resulting in more damage. There is a strong demand for improvement in toughness and sliding characteristics.

A slider containing ZrO ₂ as a main component is Al ₂
O ₃ has excellent sliding characteristics compared with -TiC, but is inferior in wear resistance and workability. As described above, various slider materials have been proposed, but there is a strong demand for a material having excellent sliding properties, wear resistance, and fracture toughness and excellent machinability.

[0011]

The present invention has been made to solve the above-mentioned problems, and Y ₂ O ₃ or MgO is added in an amount of 3-7.
The main component is tetragonal ZrO ₂ containing wt.
15-40% C, and Ti, Zr, Mo, W, Ta, Nb,
The present invention provides a substrate material for a magnetic head, especially for a thin film magnetic head, characterized by containing at least one kind of silicide of Cr in an amount of 5 to 20%.

In the present invention, tetragonal ZrO ₂ having excellent sliding properties is used as a main phase, and TiC for imparting wear resistance and conductivity is dispersed, and Ti, Zr, Mo, W, Ta, and It is possible to obtain a substrate material having a sliding property, wear resistance, and machinability, which is composed of constituent phases in which at least one of Nb and Cr silicides is added and dispersed.

The main constituent phase of the present invention, tetragonal ZrO _2, is
It is necessary to use tetragonal ZrO ₂ in which Y ₂ O ₃ or MgO is dissolved in 3 to 7%. Monoclinic ZrO when Y ₂ O ₃ and MgO are less than 3%
₂ increased, micro cracks were generated during cooling of the sintered body, and the mechanical strength significantly decreased. If it exceeds 7%, cubic ZrO
₂ is increased and the strength and fracture toughness are remarkably reduced, which is not preferable.

In the present invention, the crystal grain size of the tetragonal ZrO ₂ main phase is preferably 2 μm or less, and when it is 2 μm or less, strength and fracture toughness are improved, and machinability and chipping are reduced. You can As will be described later, at least one of TiC and specific Ti, Zr, Mo, W, Ta, Nb, and Cr silicides is dispersed in the tetragonal ZrO ₂ main phase to form crystal grains of the tetragonal ZrO ₂ phase. The growth of Zr
O ₂ phase crystal grains can be made finer.

In the present invention, TiC which imparts wear resistance and an antistatic function must be contained in a tetragonal ZrO ₂ constituent phase in a state of being uniformly dispersed. The content of TiC is 15
˜40%, which is necessary for abrasion resistance, conductivity, and refinement of tetragonal ZrO ₂ crystal grains.
% Or less is insufficient in terms of conductivity and wear resistance,
% Or more, TiC has a high hardness and sliding properties are deteriorated, which is not preferable.

In the present invention, the lubricating property is further excellent,
Suppresses the growth of tetragonal ZrO ₂ grains and imparts high thermal conductivity. At least one of Ti, Zr, Mo, W, Ta, Nb, and Cr silicides is in the tetragonal ZrO ₂ -TiC constituent phase. It is necessary to disperse and contain it. The content of these silicides is 5 to 20% in the sintered body, which is due to lubricity and tetragonal ZrO ₂
It is necessary for refining the crystal grains of 5% or less. Lubricity and high thermal conductivity cannot be exhibited at 5% or less, and a dense sintered body cannot be obtained at 20% or more. Instead, growth of tetragonal ZrO ₂ crystal grains Is not preferable.

The grain size of the raw material of the tetragonal ZrO ₂ , TiC, Ti, Zr, Mo, W, Ta, Nb, Cr solid solution of Y ₂ O ₃ or MgO constituting the present invention is the average grain size. Is preferably 0.1 μm or less. This is because if it is 0.1 μm or more, the crystal grains generated by sintering become large and the smoothness of the surface of the substrate is deteriorated, which is not preferable. Although a small amount of other components may be present as impurities,
It is preferably 0.5% or less, particularly 0.1% or less.

Although the present invention has the above-mentioned constitution, in order to produce the ceramics of the present invention, Y ₂ O ₃ of 0.1 μm or less is produced.
Or MgO solid solution ZrO ₂ powder, TiC powder, Ti, Zr,
It is possible to obtain a sintered body by using a hot press to mix at least one powder of Mo, W, Ta, Nb, and Cr silicide at a predetermined ratio, mix them well, and dry them.

Further, a small amount of binder is added to the above-mentioned mixed powder and granulated by a spray dryer, and the granulated product is C
Molded by IP, pressureless sintering or pre-fired HIP (Sinter-HIP) or capsule HIP in vacuum or non-oxidizing atmosphere
The same effect can be obtained by (encapsulating in a capsule).

Since the sintering temperature when performing this hot pressing greatly influences the performance of the obtained ceramics, 14
0 to 1600 ° C. is preferable, and when the sintering temperature is 1400 ° C. or less, a dense sintered body having a low density cannot be obtained, and 1600 ° C.
If it exceeds, the growth of crystal grains of tetragonal ZrO ₂ becomes remarkable, which is not preferable.

[0021]

[Function] As described above, tetragonal ZrO ₂ having excellent sliding characteristics
With TiC as the main phase and tetragonal ZrO with wear resistance and conductivity
₂ Zr, Ti, Mb, W that disperse in the main phase to improve machinability such as strength and fracture toughness, control lubricity and growth of tetragonal ZrO ₂ crystal grains, and impart high thermal conductivity , Ta, Nb, Cr
Of at least one of the above silicides, and exhibiting excellent sliding properties, abrasion resistance, machinability, and lubricity as a substrate material for thin-film magnetic heads due to the interaction thereof. it is conceivable that.

[0022]

EXAMPLES The present invention will be described below based on examples. ZrO ₂ powder (purity 99%, average particle size 0.03 μm) and TiC powder (purity 99%, average particle size 0.1 μm or less) and Zr containing 3 to 7% Y ₂ O ₃ or MgO as a raw material , Ti, Nb
, W, Ta, Nb, Cr silicide (purity 99%, average particle size 0.1μm or less) was mixed at a predetermined ratio, and ethanol was used in a ball mill to produce ZrO ₂ balls (partially stable). ZrO ₂ balls) for 10 hours. This mixed powder was dried with an evaporator, ethanol was extracted, dried and lightly crushed.

This powder was filled in a graphite mold of hot press, the pressure was 350 kg / cm ² , and the temperature was 1400 each.
~ 1600 ℃, hot pressed in Ar atmosphere for 1 hour, 6
A 0 mmφ × 5 mm thick sintered body was obtained.

As the physical properties of the sintered body, the density was measured by the Archimedes method, the theoretical density was divided to obtain the relative density, and the bending strength was measured according to JIS R 1601 "Bending test method for fine ceramics".

The fracture toughness is determined by the SEPB method (Single Edge P
Re-Cracked Beam method). That is JIS R 160
After preparing a sample conforming to 1 and making an indentation by Vickers indentation, a load for pre-cracking was applied, and pop-in (Pop-in) was detected with an earphone. Subsequently, coloring was performed to measure the precrack length, and a bending test was performed to measure the breaking load. After measuring the pre-crack length of the fractured sample, the fracture toughness was determined by the fracture toughness calculation formula.

The Vickers hardness was measured by a Vickers hardness meter with a load of 300 g using the mirror-polished surface of the bending test piece. Bending test pieces were used to measure the specific resistance by the four-terminal method.

60 mmφ manufactured by the same method as above
× An evaluation test as a magnetic head slider was performed using a sintered body having a thickness of 5 mm.

The obtained sintered body was mirror-polished, cut with a diamond cutting grindstone, and fine chipping at the corners was observed with a microscope. This chipping test was conducted with a resinoid grindstone (3
Using a cutter having a diamond abrasive grain of 0 μm, the cutting was performed at 0.3 mm and the feed rate was 5 mm / sec. When the chipping depth does not exceed 2 μm, it does not substantially affect the slider quality and maintains satisfactory quality.
This is indicated by ◯, when it exceeds 2 μm, it is indicated by Δ, and when it is significantly chipped, it is indicated by ×.

The slidability and wear resistance were evaluated by a CSS test in which an actual thin film magnetic head shape was cut out from a sintered body and brought into contact with a magnetic disk to rotate the disk.

For the slidability, the coefficient of friction was determined by the CSS test of the disk and the head. When the coefficient of friction was less than 0.5, it was indicated by ◯. As shown. Wear resistance is CSS
The test was repeated 10,000 times, and the presence or absence of scratches on the sliding surface of the magnetic head slider was evaluated.

As a comparative example, Al ₂ O ₃ —TiC 30% substrate and Y
ZrO ₂ —TiC 30% partially stabilized with ₂ O ₃ 5.2 wt%
Comparison was made using the substrate. The respective results are shown in Tables 1 and 2.

As shown in the results of Tables 1 and 2, the present invention has a high density, a small specific resistance, a high hardness and a high bending strength.
In particular, the fracture toughness is _{2 to 3} compared to Al ₂ O ₃ -30% TiC substrate.
3 times, ZrO ₂ (Y ₂ O ₃ 5.2% partial stabilization) -30% TiC
It is about 1.4 times better than the substrate. The bending strength shows a strength that does not pose a problem for the magnetic head slider.

In the evaluation as a magnetic head slider, almost no pores were observed when mirror-polished, and chipping resistance, abrasion resistance, and sliding characteristics were superior to those of the comparative example, and it is the most suitable slider. ..

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

The magnetic head slider (substrate) of the present invention
The material is tetragonal ZrO ₂ , which has high sliding strength and high strength and toughness, as the main constituent phase, and TiC for imparting wear resistance and conductivity.
Dispersed in the tetragonal ZrO ₂ phase, and Ti, Zr, M with excellent lubricity
O, W, Nb, Ta and Cr silicides are added and at least one of them is dispersed uniformly, and has excellent sliding characteristics, lubricity, wear resistance, machinability, and specific resistance. And small triboelectrification properties and high thermal conductivity, which is an excellent technical advantage.

Claims (2)

[Claims] 1. Tetragonal Z containing 3 to 7% by weight of Y ₂ O ₃ or MgO.
Contains rO ₂ as the main component, contains 15 to 40 wt% of TiC, and
A magnetic head substrate material comprising 5 to 20% by weight of at least one kind of silicides of Ti, Zr, Mo, W, Ta, Nb and Cr. _2. A substrate material for a magnetic head according to claim 1, wherein the average crystal grain size of tetragonal ZrO ₂ is 2 μm or less.