JPH05120635A - Substrate material for magnetic head - Google Patents

Abstract

PURPOSE:To obtain the material having excellent slidability, friction resistance and fracture toughness and small specific resistance and small triboelectrification property as an electrical property as the substrate material for magnetic heads. CONSTITUTION:This substrate material for thin-film magnetic heads is formed by incorporating 20 to 65%, by weight %, ZrO2 phase contg. at least tetragonal ZrO2 therein and essentially consisting of the balance TiB2.

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 material having excellent durability and wear resistance.

[0002]

2. Description of the Related Art In recent years, magnetic heads, particularly 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 face of a ceramic slider serving as a substrate, and the slider rotates at a high speed (2
(0 to 40 m / s), it has a function of writing and reading data on and from the magnetic disk by utilizing the fact that it slightly floats (0.2 to 4 μm) on the surface of the magnetic disk by riding on the laminar air flow. . Therefore, the slider does not obtain a sufficient air laminar flow when starting and stopping the rotation of the magnetic disk, so that the slider always slides on the magnetic disk and performs 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 shown 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, JP-A-60-1
There are those disclosed in JP-A-83709 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 mainly composed of ZrO ₂ system are disclosed, for example, in JP-A-60-171617 and JP-A-63.
Many sliders are proposed in JP-A-278312 and JP-A-60-66404, and sliders having good sliding characteristics have 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, it does not have many cracks and chippings, which reduces the processing yield, resulting in more fracture toughness. It is strongly desired to improve sliding characteristics.

A slider containing ZrO ₂ as a main component is Al ₂
It has better sliding properties than O ₃ -TiC, but is said to have poor 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 contains ₂₀ to 65% by weight of ZrO ₂ phase containing TiB ₂ as a main component and containing at least tetragonal ZrO _2. The present invention provides a substrate material for a magnetic head, especially a thin film magnetic head.

The present invention is directed to wear resistant, high hardness, conductive TiB ₂
, Which is a main constituent phase, and which is composed of a sintered body in which monoclinic and tetragonal ZrO ₂ with excellent sliding characteristics and fracture toughness coexist, or tetragonal ZrO ₂ is dispersion strengthened, wear resistance Therefore, a substrate material having excellent machinability can be obtained.

In the present invention, ZrO ₂ phase containing at least tetragonal ZrO ₂ and TiB ₂ are weight% (hereinafter the same), the former is 20 to 65%, and the latter is the balance.
The reason for these limitations is that when the ZrO ₂ phase is too much, the specific resistance becomes high and the charging property becomes high, and the formation of titanium zirconium boride solid solution in the grain boundary layer decreases and the ZrO ₂ phase decreases.
Fracture toughness for crystal growth easily occurs in O ₂ is for of such a decrease, TiB ₂ is high hardness is too small, it becomes difficult to have sintered at hardly sintered, a monoclinic ZrO ₂ When used together with tetragonal ZrO ₂ , cracks are generated due to volume change accompanying transition, and when only tetragonal ZrO ₂ partially stabilized with Y ₂ O ₃ or MgO is used, fracture toughness is improved. Is less effective for. The desirable ratio is 30 for the former
˜60%, balance TiB ₂ .

The dispersion-strengthened phase ZrO ₂ of the present invention must be at least tetragonal ZrO _2, particularly Y ₂ O ₃ or tetragonal ZrO _{2 in} which MgO is dissolved in 3 to 7%. When coexisting with monoclinic ZrO ₂ , it is a powder that is not solid-dissolved with Y ₂ O ₃ or MgO. If it is 20% or less of the total amount with TiB ₂ , the transition from monoclinic to tetragonal is small. Therefore, it is not preferable because cracks occur and the sintered body cannot be removed. When the content is 65% or more, the zirconium titanium boride solid solution formed in the grain boundary layer is less produced, and ZrO ₂ grains are significantly produced, which is not preferable.

[0015] Also in ZrO ₂ in the case of tetragonal ZrO ₂ Y ₂ O
_{When the} content of ₃ or MgO is less than 3%, monoclinic ZrO ₂ increases and microcracks occur during cooling of the sintered body, resulting in a significant decrease in mechanical strength. When it is more than 7%, cubic ZrO ₂ increases and strength increases. However, the fracture toughness is lowered, which is not preferable.

In the present invention, TiB _{2 as a} main component, at least tetragonal ZrO _{2 as} a dispersion strengthening agent, and this and monoclinic Z.
The phase in which rO ₂ coexists and the grain boundary layer are composed of zirconium titanium boride solid solution produced by the reaction of TiB ₂ and ZrO _2, and the crystal grain size of these constituent phases is preferably 2 μm or less, When the thickness is 2 μm or less, strength and fracture toughness are improved, and machinability and chipping can be reduced.

In the present invention, in order to further reduce the crystal grain size, the grain size of the raw material used is made fine, and the average grain size is 0.
The thickness is required to be 1 μm or less, and if it exceeds 0.1 μm, the crystal grains generated by sintering become large and the smoothness of the surface of the substrate is lowered, 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 sintered body of the present invention, TiB ₂ powder of 0.1 μm or less,
Monoclinic ZrO ₂ powder or Y ₂ O ₃ or tetragonal ZrO ₂ powder was dissolved in MgO were mixed in a predetermined mixing ratio and dried thoroughly mixed and pulverized to obtain a sintered body using a hot press be able to. Also, a small amount of binder is added to the above-mentioned mixed powder and granulated by a spray dryer, and the granulated product is molded by CIP, and pressureless sintering or pre-calcined HIP (Sinter-HIP) in a vacuum or non-oxidizing atmosphere. ) Or a capsule HIP (encapsulated in a capsule), the same effect can be obtained.

The sintering temperature when performing this hot pressing greatly affects the performance of the obtained ceramics.
0 to 1700 ° C is preferable, and when the sintering temperature is 1500 ° C or lower, a dense sintered body having a low density cannot be obtained, and 1700 ° C.
If it exceeds, the grain growth of the coexisting phase of TiB ₂ and the monoclinic and tetragonal ZrO ₂ which are the constituent phases becomes remarkable, which is not preferable.

[0021]

In the present invention, the conductive, high hardness and wear resistance
The TiB ₂ as a main component, sliding characteristics, ZrO ₂ or its monoclinic ZrO ₂ excellent tetragonal fracture toughness coexist a sintered body obtained by dispersion strengthening by further grain boundary layer is a TiB ₂ ZrO ₂
Zirconium borate solid solution (ZrTi) B ₂ formed by the reaction with the compound suppresses the grain growth of the constituent phases to form a fine microstructure with no pores, optimized by the interaction of these Is considered to exhibit excellent sliding properties, abrasion resistance, and machinability as a substrate material for thin-film magnetic heads.

[0022]

EXAMPLES The present invention will be described below based on examples. TiB ₂ powder as raw material (purity 99%, average particle size 0.1 μm
Below) and monoclinic ZrO ₂ powder (purity 99%, average particle size 0.0
3 μm) or Y ₂ O ₃ or MgO in a solid solution of 3 to 7%, tetragonal ZrO ₂ powder (purity 99%, average particle size 0.03 μm) was mixed at a predetermined ratio, and ethanol solvent was mixed with a ball mill. Used ZrO ₂ balls (partially stabilized ZrO ₂ balls) were mixed and ground 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 1500, respectively.
~ 1700 ℃, hot pressed for 1 hour under Ar atmosphere, 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 indenter press-fitting, a load for pre-cracking was applied and the earphone detected pop-in. 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
-Partially stabilized with TiC 30% substrate and Y ₂ O ₃ 5.2%
Comparison was performed using a ZrO ₂ —TiC 30% 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.
Especially, the fracture toughness is _{2 to 3} % compared to Al ₂ O ₃ -30% TiC substrate.
2.5 times, ZrO ₂ (Y ₂ O ₃ 5.2% partial stabilization) -30%
It is about 1.3 times better than the TiC 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. .

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

The magnetic head substrate of the present invention has a wear resistance,
It is a dense sintered body with conductive and high-strength TiB ₂ as the main constituent phase and dispersion strengthened with tetragonal ZrO ₂ that has high toughness and excellent sliding characteristics. Sliding characteristics, wear resistance, mechanical properties It has the technical advantages of excellent workability, low specific resistance, low triboelectricity, and high thermal conductivity.

Claims (3)

[Claims] 1. TiB ₂ as a main component and at least tetragonal ZrO ₂
A substrate material for a magnetic head, comprising ₂₀ to 65% by weight of ZrO ₂ containing. 2. The substrate material for a magnetic head according to claim 1, wherein the tetragonal ZrO ₂ contains 3 to 7% by weight of Y ₂ O ₃ or MgO in ZrO ₂ . 3. A substrate material for a magnetic head according to claim 1, wherein the constituent phase is titanium boride, monoclinic and tetragonal ZrO ₂ and the grain boundary layer is titanium zirconium boride solid solution.