JPH071531B2 - Thin film magnetic head slider and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film magnetic head slider for a magnetic disk device, and more particularly to a slider for improving the life of the magnetic disk and a manufacturing method thereof.

[Conventional technology]

In the field of magnetic disk storage devices, the levitation gap between magnetic disks and magnetic heads is becoming narrower in order to meet the increasing demand for higher recording density, and the practical application of thin film magnetic heads and thin film disks with good magnetic characteristics is being promoted. Is being considered.

The thin film magnetic head slider is provided with a thin film element on its end face, is held in contact with the surface of the magnetic disk, and has a function of levitating on the surface of the magnetic disk by an air flow generated on the surface of the magnetic disk rotating at a high speed. Therefore, the slider slides transiently with the magnetic disk when the magnetic disk rotation is started and stopped. Furthermore, the levitation clearance is narrowed (0.1
~ 0.3 μm), the chances of unexpected contact and sliding between the slider and magnetic disk will increase. For this reason,
The damage of the magnetic disk caused by the contact and sliding of the slider is a problem. In particular, in the case of a thin film disk, it becomes a big problem. That is, since the thickness of the magnetic material of the thin film disk is extremely small (0.05 to 0.1 μm), the allowable damage size is extremely small. Therefore, a slider that does not damage the magnetic disk is strongly desired.

As a conventional slider, there is typically an Al ₂ O ₃ / TiC sintered body disclosed in Japanese Patent Publication No. 58-5470. The Al ₂ O ₃ / TiC sintered body has good workability and is suitable for processing and manufacturing a thin film magnetic head with a good yield, but it is not always a satisfactory material for damage to the above-mentioned magnetic disk.

In order to solve this problem, for example, the method disclosed in JP-A-58-150122 has been proposed. This is a method in which the sliding surface of the slider with respect to the magnetic disk is coated with a lubricating substance such as MoS ₂ or C. The coating of the lubricating material certainly improves the life of the magnetic disk. However, a thin coating does not last long, whereas a thick coating substantially increases the floating gap, which is disadvantageous in improving the recording density.

On the other hand, a ZrO ₂ sintered body disclosed in, for example, Japanese Patent Application Laid-Open No. 58-121179 has been proposed as a slider that causes less damage to the magnetic disk itself. This material is certainly less damaged by the magnetic disk due to contact and sliding. However, the life of the magnetic disk is not always sufficient in a long-term continuous operation in which a minute floating clearance of the slider is maintained.

[Problems to be solved by the invention]

As described above, the conventional slider has a problem in the life of the magnetic disk. That is, it is difficult for the method of coating the sliding surface of the magnetic disk of the slider with a lubricating film to achieve both long life of the magnetic disk and high recording density. On the other hand, even when a ZrO ₂ sintered body, which shows improved slidability, is used, a sufficient magnetic disk life cannot always be obtained in practical use. This is because the ZrO ₂ sintered body is an electrical insulator, so dust in the atmosphere adheres due to electrostatic attraction, causing unexpected contact between the flying slider and the magnetic disk, which causes This is because the frequency of contact of the disks becomes large.

An object of the present invention is to provide a slider for a thin film magnetic head capable of narrowing the flying gap and not damaging the magnetic disk for a long period of time.

[Means for Solving the Problems] In order to achieve the above object, the present inventors have made efforts to impart conductivity to the ZrO ₂ sintered body, and have completed the present invention. That is, it has been found that the above object can be achieved by incorporating a crystal grain boundary phase containing at least C inside the slider material.

[Action]

 The present invention will be described in detail below.

In order to achieve the object of the present invention, ZrO ₂ is used as the base material of the slider material. The present inventors have found that C-added ZrO ₂
In the present invention, it was found that by selecting an appropriate firing temperature, C content, and firing atmosphere, a phase containing C is generated at grain boundaries and a sintered body having no pores inside is obtained. Was reached. That is, if the firing temperature is less than 1650 ° C, the grain boundary phase does not occur for any C content, so the firing temperature must be 1650 ° C or higher. On the other hand, when the firing temperature exceeds 2000 ° C., the crystal grains of the sintered body become extremely large, and chipping caused by processing becomes large, which is not preferable, and there is a problem in terms of firing cost. In order to prevent the problem of chipping, the crystal grain size needs to be 5 μm or less. Therefore, the firing temperature is preferably 1650 ° C to 2000 ° C.

On the other hand, if the C content is less than 0.2% by weight, some or most of C reacts with ZrO ₂ to produce ZrC crystal grains, which is not effective, and 0.2% by weight or more is required to produce the grain boundary phase. C content of is required. On the other hand, when the C content exceeds 2% by weight, C remarkably hinders the sintering of ZrO ₂ , and pores remain inside the sintered body, which is not preferable as a material such as a slider that requires precision processing. Therefore, the C content is preferably 0.2 to 2% by weight. Further, when the firing atmosphere is oxidizing, the added C is dispersed as CO or CO ₂ gas, and therefore the firing atmosphere needs to be non-oxidizing.

In order to obtain microscopic uniformity of the slider material, it is preferable that the phase containing C be uniformly generated at the grain boundaries. For this purpose, C and ZrO ₂ powder must be mixed very uniformly before firing. For this purpose, it is desirable to dissolve the organic substance that thermally decomposes to produce C in a suitable solvent and mix it with the ZrO ₂ powder.

Since the generated C-containing phase has conductivity, the existence of this phase at the grain boundaries makes the entire sintered body conductive. As a result, the slider is prevented from being charged, and the adhesion of dust in the atmosphere to the slider due to electrostatic attraction is reduced. Dust adhesion to the slider is one of the major causes of disturbing the flying stability of the flying slider and causing unexpected contact between the slider and the disk.
Therefore, the operating life of the magnetic disk can be extended by the conductivity of the slider.

In the present invention, at least a part of the phase containing C can be made amorphous. This has the following advantages. That is, since the amorphous phase containing C has weaker mechanical strength than the ZrO ₂ crystal of the base material, it preferentially wears due to sliding. As a result, due to sliding with the magnetic disk, extremely fine C wear powder is present on the sliding surface of the slider, and this serves as a lubricant to further improve the sliding characteristics. Further, the presence of the amorphous phase softens the hardness of the slider, so that the magnetic disk is less damaged by the contact.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

Example 1 ZrO ₂ powder having a particle diameter of 0.1 μm (however, 8 mol% of Y ₂ O ₃ was solid-dissolved) was added to 0, 0.2, 0, 4, 2.0, 4.0, 5.0% by weight of novolak. The phenol resin was dissolved in acetone and added, and the mixture was kneaded with a ball mill for 48 hours. Novorask
The phenolic resin produces about 50% by weight of added C by thermal decomposition. After the obtained mixture is dried, it is pressed into a mold,
It was subjected to hot press firing. In hot press firing, a sample is loaded into a graphite mold, the graphite mold is subjected to high-frequency induction heating in a vacuum atmosphere of 10 ^-4 Torr, and a load is applied to the graphite mold with a hydraulic press to compress the sample at a pressure of 500 kgf / cm ^2. I went. Firing is 18
I went to 00 ℃ for 1 hour.

The sintered body thus obtained was first analyzed for the C content.
Next, the microstructure of the sintered body was observed using an electron microscope. Further, the surface of the sintered body was polished with a lapping machine and observed with a microscope to check the presence or absence of pores. Moreover, the electrical resistivity was measured.
Table 1 shows these results. In the observation with an electron microscope, the presence or absence of C in the grain boundary phase was examined by the energy loss measuring method, and the crystallinity of the grain boundary phase was examined by the presence or absence of the halo phenomenon in the diffraction pattern observation.

From Table 1, it can be seen that the grain boundary phase containing C is present in the products of the present invention containing 0.2% by weight or more of C (Sample Nos. 2, 3, 4). Further, it is understood that the electrical resistivity of the sintered body is remarkably lowered due to the generation of the grain boundary phase. On the other hand, in the product of the present invention containing 2% by weight or less of C, no porosity is observed, while 2.
The sintered body containing 5% by weight of C (Sample No. 6) has pores. When a sintered body having pores was processed into a slider shape under constant processing conditions, many cracks and holes were generated, and it was unsuitable as a slider.

As a result of observation with an electron microscope, the generated grain boundary phase was C
An amorphous phase containing was found.

FIG. 1 is a scanning electron micrograph of a typical fracture surface of a ZrO ₂ sintered body according to the present invention. A grain boundary phase containing C is recognized between ZrO ₂ crystal grains.

Example 2 To the same ZrO ₂ powder as described in Example 1, 2.0 wt% of Novolac phenol resin was dissolved in acetone and added, and the mixture was kneaded by a ball mill for 48 hours. The resulting mixture was dried, pressed into a mold, and hot pressed by the same method as described in Example 1. However, the firing temperature is 16
The test was performed in 5 ways, 00 ℃, 1650 ℃, 1800 ℃, 2000 ℃, and 2050 ℃.

The obtained sintered body was examined for C content, microstructure, and electric resistivity in the same manner as in Example 1. Furthermore, the size of the crystal grain size was examined. Table 2 shows these results.

It can be seen from Table 2 that the grain boundary phase containing C is present in the product of the present invention (Sample Nos. 8, 4, 9) having a firing temperature of 1650 ° C. or higher. It is also found that the electrical resistivity of the sintered body is remarkably reduced due to the formation of this phase. On the other hand, the firing temperature is 2000
At 2050 ° C (Sample No. 10), which exceeds ℃, the crystal grain size is 9.1.
It is as large as μm. When an attempt was made to process this sintered body into a slider shape, large chipping comparable to the grain size occurred and it was unsuitable as a slider.

As a result of observation with an electron microscope, an amorphous material containing C was observed in the produced grain boundary phase.

Example 3 Using the sintered bodies of sample numbers 1 to 5 and 7 to 9 obtained in Example 1, a slider was processed as shown in FIG. FIG. 2 is a perspective view showing an example of a thin film magnetic head slider,
The slider has a thin film element forming surface 3 and a magnetic disk sliding surface 4.

The characteristics of the slider obtained by the processing with respect to the life of the magnetic disk were examined by the following method. First, in the slider, the sliding surface of the magnetic disk was placed on the magnetic disk and held by the gimbal spring on the magnetic disk surface. Next, rotate the magnetic disk at a rotational speed such that the peripheral speed at the slider position is 40 m / sec,
The slider was floated by 0.3 μm, and after 30 seconds, the magnetic disk stopped rotating. By repeating the above starting and stopping of the rotation of the magnetic disk, the time until the gimbal spring was suddenly loaded due to damage to the magnetic disk was measured. As the magnetic disk, a coating type disk was used in which an organic resin obtained by kneading Fe ₂ O ₃ magnetic powder and Al ₂ O ₃ filler powder was coated as a magnetic layer on the surface of an Al disc.

Table 3 shows the measurement results. As shown in Table 3, a ZrO ₂ sintered body (sample number 3,4,5,8,9) containing a grain boundary phase containing C and having an electrical resistivity of 10 ⁸ Ωcm or less was not used in the conventional ZrO ₂ It can be seen that the life of the magnetic disk is at least about twice as long as that of the sintered body (Sample Nos. 1, 2, 7).

In addition, partially stabilized ZrO ₂ may be used as ZrO ₂ of the present invention.

Partially stabilized ZrO ₂ (PSZ) has attracted attention as a ceramic with excellent wear resistance and toughness. However, the following points are serious problems for its practical use. That is, PSZ has extremely poor workability. Since PSZ has mechanical properties of good wear resistance and toughness,
On the contrary, in the case of processing, the processing is extremely difficult and the cost becomes high. Even if an attempt is made not to leave a processed portion after firing in order to solve this point, the molded body undergoes a dimensional change (shrinkage) of several tens of percent before and after firing, so that it is difficult to control the dimension with high accuracy. For this reason, PSZ has excellent mechanical properties, but it is difficult to put it into practical use in high-precision products and complex-shaped products.

According to the present invention, PSZ can be made conductive by adding C. As a result, PSZ electrical discharge machining becomes possible, and high precision products and complex shaped products become possible. Moreover, since the amount of C added is at most 2%, the excellent mechanical properties of PSZ are not impaired at all. Furthermore, in addition to the wear resistance of PSZ, it has the advantage of being lubricated by C.

This PSZ is suitable as a sliding member, for example, as a wheel bearing, a bearing member, a nozzle member, or the like, but since it is particularly conductive and can prevent charging, it can be used as a guide roller for a magnetic tape. It is suitable as a sliding member for magnetic equipment.

〔The invention's effect〕

According to the present invention, it is possible to obtain a slider material that does not damage the magnetic disk for a long period of time, so that the floating gap of the thin film magnetic head can be reduced, the recording density of the magnetic disk storage device can be improved, and the magnetic disk Effective in extending the life.

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph showing the grain structure of crystals of the ZrO ₂ sintered body according to the present invention. FIG. 2 is a perspective view showing an example of the thin film magnetic head slider. 1 ... Grain boundary phase containing C, 2 ... ZrO ₂ crystal grains, 3 ... Thin film element forming surface, 4 ... Magnetic disk sliding surface.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaki Oura 2880, Kozu, Odawara, Kanagawa Stock company Hitachi Ltd. Odawara factory (72) Inventor Kanen Nagaike 2880, Kozu, Odawara, Kanagawa Hitachi Odawara In the factory (56) References JP-A-60-66361 (JP, A) Actually developed Shou 60-51666 (JP, U)

Claims (5)

[Claims] 1. A 0.2 to 2.0% by weight of the thin-film magnetic head slider phase containing C is characterized in that it consists of ZrO ₂ sintered body present in ZrO ₂ grain boundaries. 2. The thin-film magnetic head slider according to claim 1, wherein at least a part of the phase containing C is amorphous. 3. C or an organic substance which produces C upon thermal decomposition and Zr
A method of manufacturing a thin-film magnetic head slider, which comprises firing the mixture with O ₂ powder at a temperature of 1650 to 2000 ° C. in a non-oxidizing atmosphere. 4. The method of manufacturing a thin film magnetic head slider according to claim 3, wherein the organic substance and the ZrO ₂ powder are mixed by dissolving the organic substance in a solvent. 5. A method of manufacturing a thin film magnetic head slider according to claim 3, wherein a phenol resin is used as the organic substance.