JP3325439B2 - Slider for magnetic head and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to ceramic substrates for magnetic heads, sliders for various magnetic heads, spacers for magnetic heads, magnetic tape guides, non-magnetic ceramics used for micromachine parts and the like, and more particularly to computers. The present invention relates to a non-magnetic ceramic which is most suitable as a material for a slider of a magnetic head used for magnetic recording such as a hard disk, a magneto-optical disk, a floppy disk, a magnetic tape, an audio recorder and a video tape recorder.

[0002]

2. Description of the Related Art In recent years, high densification of magnetic recording has made rapid progress. With this high density, high coercivity media such as hard disks, 8 mm VTRs, electronic still cameras, video floppies and digital audio have been developed. Conventionally, a magnetic head using ferrite or the like has been used as a recording / reproducing magnetic head.

In recording on a magnetic medium using such a magnetic head, a composite slider is employed as one of the methods for achieving a high linear density and a high track density corresponding to an increase in capacity. In a so-called composite type magnetic head, a magnetic head core is bonded to a ceramic slider. The magnetic head core and the slider are bonded by setting the atmosphere at a high temperature of about 400 ° C. and melting the glass disposed therebetween.

As a characteristic required of such a slider material, it is necessary to have excellent sliding characteristics with a magnetic medium. The track density of a high-density recording head is 10 μm or less, and the slider material used for them is required to have a small pore. Furthermore, in the case of a magnetic head for a hard disk, the head rotates while the disk rotates.
A method called S (Contact Start / Stop) is employed. In this CSS method, the disk and the head slide in contact immediately after the disk is started and immediately before the disk is stopped. Therefore, if there is a pore in the slider part when sliding, lubricant or magnetic wear powder or the like adheres to the pore part or adheres from the pore part, thereby destroying the magnetic medium, data destruction or the head. And the reliability of the magnetic recording device is significantly reduced.
In particular, in recent years, the distance (flying height) between the magnetic disk and the head during operation has become smaller, and the magnetic film of the magnetic disk has become thinner, and the magnetic disk is more easily damaged. From this point, a material having a small pore size is required for the slider material.

In recent years, the flying height of the magnetic head from the disk surface has been reduced to submicron or less with the increase in the recording density of the Winchester type magnetic head. The flying height of the slider changes due to the difference in speed. In order to reduce the change in the flying height, not only the conventional positive pressure portion is provided on the air bearing surface, but also a minute groove (recess) is formed on a part of the sliding surface to form a negative pressure portion. It is practiced to make the flying height of the head constant at the inner and outer circumferences.

Therefore, for the above-described reason, the slider material is polished on the sliding surface, and then the groove (recess) is formed on the sliding surface.
To form This rail is generally machined, but when a negative pressure slider having a groove of several μm is formed, it is processed by milling with an ion beam, reactive ion milling, chemical etching, or the like.

At present, slider materials such as calcium titanate (CaTiO ₃ ) and barium titanate (B
aTiO ₃ ), alumina-titanium carbide (Al ₂ O ₃ -T)
iC) materials are used, and their thermal expansion coefficients are 100 to 120 × 10 ⁻⁷ / ° C. for calcium titanate, 80 to 100 × 10 ⁻⁷ / ° C. for barium titanate, and 70 to 100 × 10 ⁻⁷ / ° C. for alumina-titanium carbide. 80 × 10 ⁻⁷ / ° C.

On the other hand, as a head core in a composite head, a composite core using Mn—Zn ferrite or a thin film having high magnetic permeability is generally used. Since the core and the slider are glass bodyed, a slider having a thermal expansion coefficient close to that of the core is adopted. For example,
The thermal expansion coefficient of Mn-Zn ferrite is 105 to 130 ×
Calcium titanate-based material is widely used as a nonmagnetic slider material which is as large as 10 ⁻⁷ / ° C. and can be used for this ferrite core. The composite core using the thin film has a coefficient of thermal expansion of 115 to 105 × 10 ⁻⁷ / ° C.
Calcium titanate-based materials are often used as slider materials. Further, in generating a narrow sharp recording magnetic field corresponding to high-density recording, a non-magnetic slider material is adopted so as not to affect a magnetic circuit.

[0009]

As described above, in the manufacturing process of the slider for the magnetic head, when the concave portion is formed on the air bearing surface and the negative pressure portion is provided, the sliding surface is finely processed by ion milling or the like. There is a need. However, the conventional titanium oxide composite material such as calcium titanate has a problem that defects called pits are generated on the processed surface after ion milling.

[0010] Therefore, lubricant or magnetic wear powder adheres to the pit portion, or deposits fall off from the pit portion,
As a result, there is a problem that the magnetic medium is destroyed, data is destroyed, and the head is damaged, and the reliability of the magnetic recording apparatus is significantly reduced. Therefore, in recent years, a material having a small defect on a processed surface by ion milling has been required.

In addition, the conventional slider material for a composite head made of a calcium titanate-based material has a large frictional force and an adhesive force with a disk, which causes a head crash or the like, which lowers the reliability of the information recording apparatus. There was a problem. In order to enhance the reliability of the magnetic head, there is a demand for a material which has a small interaction between the magnetic head and the disk and which does not damage the medium or the head and has excellent sliding characteristics.

In order to reduce the interaction between the recording disk and the recording or reproducing head, it has been proposed to make the flying surface of the head into a crown shape. The size of the crown shape is several nanometers. In order to manufacture this with high accuracy, it is necessary to increase the precision of processing jigs and devices, and it has been difficult to mass-produce the device at low cost. Also,
If pores having a size exceeding 2 μm exist on the sliding surface, there is a problem that the medium is damaged when the slider slides on the medium.

Further, as a core material, a composite core using a Mn-Zn ferrite having a high magnetic permeability or a magnetic thin film is used in place of the Ni-Zn ferrite in order to respond to a higher density of magnetic recording. Has a coefficient of thermal expansion of 10
There is a problem that the coefficient of thermal expansion of the slider is different from this value, which is as large as 5 to 115 × 10 ⁻⁷ / ° C. For this reason,
There is a problem in manufacturing the magnetic head, such as stress acting on the core due to the heat treatment at the time of glass welding, deteriorating the magnetic properties and generating cracks in the core.

[0014]

Means for Solving the Problems The present inventors have studied the above problems, and as a result, as a slider for a magnetic head, 95.0 to 99.95% by weight of Fe ₂ O ₃ and 0.
The 05 to 5.0 wt% of ZrO ₂ as a main component, composed of a sintered body of non-magnetic ceramics containing 0.5 to 0.01 parts by weight of Mn to these 100 parts by weight of the main component, the sintered body Has a relative density of 99% or more and a pore size of 2 μm or less.

[0015]

That is, according to the present invention, Fe ₂ O ₃
By setting the content by weight or more, it is possible to obtain a material which is capable of precision processing, has few pits on a finely processed surface by chemical etching or ion milling, and is less likely to damage a medium or a head by CSS and has excellent sliding characteristics. I found that I could do it.

The non-magnetic ceramic of the present invention has a thermal expansion coefficient of 106 to 108 × 10 ⁻⁷ / ° C. and is glass-bonded to a Mn—Zn ferrite core having a large magnetic permeability or a composite core using a thin film. It is possible. Moreover, by setting the average particle size of the raw material to 1.0 μm or less, it is possible to obtain a dense porcelain in which the size of the underlying pores is 2 μm or less.

The reason why the content of Fe ₂ O ₃ is set to 95% by weight or more is that ZrO ₂ , Mn compound, CeO ₂ , Ti
When a large amount of components of O ₂ and SiO ₂ is contained, irregularities are generated on the processed surface due to the difference in the milling rate between the compositions. Therefore,
By increasing the content of Fe ₂ O _3, sub-components other than Fe ₂ O ₃ is by uniformly dispersed in fine, it is possible to reduce the pit of the processing surface by ion milling.

In view of the frictional force with the disk and the presence or absence of damage after CSS, it is desirable that Fe ₂ O ₃ be contained in an amount of 99.0% by weight or more. From the viewpoint of good processing, the average particle diameter of Fe ₂ O ₃ constituting the material is desirably 10 μm or less, preferably 5 μm or less.

Further, ZrO ₂ which is a sintering aid
The reason why the content is set to ５5% by weight is that if it exceeds 5% by weight, the effect of reducing pits after ion milling described above is poor, and
In addition, cracks may occur during firing, while if it is less than 0.05% by weight, sinterability is reduced.

The Mn element acts as a sintering aid,
The reason for setting the content to 0.01 to 0.5 part by weight is that 0.1 part by weight is used.
If the content exceeds 5 parts by weight, a composite compound phase of Mn having a particle diameter of 1 μm or more is generated, and the irregularities on the ion milled surface become large, which is unsuitable as a slider material. On the other hand, since Mn is contained as an unavoidable impurity in Fe ₂ O ₃ , it is difficult to manufacture it industrially at a low cost with less than 0.01 part by weight.

Further, the non-magnetic ceramic of the present invention comprises:
Components other than these may be contained in a total range of 3% by weight or less. For example, 0.036% by weight or less of SiO ₂ ,
It may contain up to 0.032% by weight of Al ₂ O ₃ and up to 0.02% by weight of Y ₂ O ₃ .

Ferrite has different magnetic properties depending on the crystal structure. Mn-Zn ferrite, Ni-Zn ferrite and the like exhibit ferromagnetism because the crystal has an inverse spinel structure, but have a positive spinel structure or a corundum type crystal. Ferrite having a structure becomes a nonmagnetic material. Fe ₂ O of the present invention
Ceramics containing ₃ as a main component are non-magnetic ceramics because of their corundum-type crystal structure.

Next, the present invention relates to a method for producing Fe ₂ O ₃
Powder, a slurry containing a raw material powder having an average particle diameter of 1.0 μm or less composed of ZrO ₂ powder and MnO ₂ powder is filled in a mold, and a solvent in the slurry filled in the mold is separated using a filter. After the pressure molding, the obtained molded body is fired by hot pressing or hot isostatic pressure treatment to produce a slider for a magnetic head made of non-magnetic ceramics.

[0025]

That is, in the method for producing a nonmagnetic ceramic of the present invention, it is important to use a raw material powder containing 95% by weight or more of Fe ₂ O _{3 and} having an average particle size of 1.0 μm or less. Then, a dense sintered body can be obtained by wet molding using the raw material powder. Alternatively, the compact or sintered compact of the raw material powder is hot pressed or HIPed.
By performing the treatment, a dense sintered body can be obtained.

Here, the average particle size of the raw material powder is 1.0 μm
The following refers to a 50% particle size by a Microtrack, that is, a graph of particle size and an integrated volume fraction of 50%.
% Means that the particle size is 1.0 μm or less. By using such a raw material powder having an average grain size of 1.0 μm or less, a nonmagnetic ceramic having a fine crystal grain size with an average crystal grain size of a sintered body of 10 μm or less can be produced. Moreover, by setting the average particle size to 1.0 μm or less, the temperature range during pre-baking before hot pressing or HIP processing can be set to a wide range of 950 to 1200 ° C., and the relative density of 99% or more Is obtained, and the subsequent HIP processing becomes possible.

That is, if the average particle size of the raw material powder exceeds 1.0 μm, the range of the pre-firing temperature is limited, and the relative density
% Or more, it is difficult to obtain a stable pre-sintered body. Then, as the pre-firing temperature increases, the crystal grain size of the sintered body increases, and pores remain in the sintered body, which makes it difficult to remove the pores by HIP treatment.

When the density of the pre-sintered body is low, the number of pits generated on the processed surface finely processed by ion milling increases even if the sintered body is densified, which makes it unsuitable as a slider material. . For example, if the firing temperature is 120
When the temperature exceeds 0 ° C., the crystal grain size of iron oxide becomes 15 μm or more, not only the strength is reduced, but also the pit size generated on the processed surface finely processed by ion milling is large, which is not suitable as a slider material.

For the above reasons, the average particle size of the raw material powder is set to 1.0 μm or less. In order to obtain a sintered body having no pores of 1 μm or more, the average particle size of the raw material powder is set to 0.7 μm or less.
It is more preferable that the thickness be not more than μm.

In the case of molding such a raw material powder, wet molding is performed. For example, the average particle size of the raw material is 0.6μ
m is filled with a slurry containing powder containing 95% by weight or more of iron oxide in a mold, and the powder is pressed under a pressure of 500 kg / cm ² or more while separating the solvent using a filter. A dense and uniform molded body that could not be obtained by molding was obtained, and the sintered body obtained by firing this molded body in an oxidizing atmosphere did not show pores of 2 μm or more.

Further, in the present invention, the pores of 2 μm or more in the sintered body can be removed by employing hot pressing or HIP processing during firing. Here, hot pressing is performed using a carbon type or SiC
Mold and zirconia mold are filled with the raw material powder, and the pressure is 50-50.
0 kgf / cm ² , 0.5 at a temperature of 1000 to 1200 ° C.
Perform for ~ 5 hours. The HIP treatment is performed in an argon or nitrogen atmosphere at a pressure of 500 to 2000 kgf / cm ² ,
Suitably, it is carried out at a temperature of 1000 to 1200 ° C. for 1 hour.

Among these production methods, in particular, a high-density sintered body can be obtained by forming a raw material powder by wet molding and then subjecting a pre-sintered body produced by a firing furnace in an oxidizing atmosphere to hot isostatic pressure treatment. .

[0034]

EXAMPLE 1 Iron oxide (Fe ₂ O ₃ ) raw material and zirconia (ZrO ₂ )
Manganese oxide (MnO ₂ ) and the composition of the final sintered body were as shown in Table 1.
And crushed and mixed using a ball mill to obtain the average particle diameter shown in Table 1. The addition amount of zirconia was replaced by the amount of abrasion mixed by a ball mill.

Each raw material is pulverized and mixed, then dried, a binder such as paraffin wax is added, and the mixture is sized through a 40 mesh. Then, the mixture is filled in a cemented carbide mold, and a pressure of 1500 kgf / cm ² is applied. In addition, dry molding was performed. After heat-treating the obtained molded body at 400 ° C. for 5 hours to remove the binder in the molded body, pre-baking is performed at 950 ° C. to 1200 ° C., and argon gas is further heated at 1000 to 1100 ° C. using a hot isostatic press. The medium was pressurized. Table 2 shows the properties of the obtained sintered body.

[0036]

[Table 1]

[0037]

[Table 2]

Here, the Archimedes method was used for the specific gravity.
The Vickers hardness was measured using an AVK (manufactured by Akashi Seisakusho) hardness tester.
After adding f for 15 seconds, it was measured from the size of the indentation by the indenter. A sample having a Young's modulus of 3 × 4 × 40 mm was prepared and measured by a pulse echo method. The presence or absence of pores was determined by polishing using a 1 μm diamond abrasive, and then observing the polished surface with a scanning electron microscope to determine the presence or absence of pores of 2 μm or more.

Next, the sample was subjected to ion milling using a milling device manufactured by Seiko Electronics Co., Ltd.
The presence or absence of pits of m or less was confirmed.

As shown in Table 2, the embodiment of the present invention (No.
Nos. 2 to 6 and 8 to 9) had high relative densities and hardness, no pores or pits after milling, and showed excellent results.

Next, 1.6 × 2.2 ×
A slider having two rails of 0.9 mm size was prepared, and a CSS tester manufactured by Haruna Tsushin Co., Ltd. was used.
A test was performed to evaluate the number of S times, damage to the disk, and damage to the head. The test method was performed by sliding a slider on the disk, and the maximum rotational speed of the disk was set to 36.
00 rpm, the time of 3600 rpm from the stop is 5 seconds, and after holding at 3600 rpm for 3 seconds,
After a lapse of seconds, the operation was stopped, and the stopped state was set to 5 seconds. This operation is called C
The number of SS was 1.

As a result, Samples No. 1 and 10
In this example, the number of CSSs was 30,000, which caused damage to the disk and the head.
It was confirmed that the samples Nos. 6, 8 and 9 had no damage to the disk or the head even when the CSS frequency was 40,000, and exhibited excellent sliding characteristics.

Example 2 A raw material having an average particle diameter of 0.6 μm was used as iron oxide, weighed so that the composition of the final sintered body was as shown in Table 3, and pulverized and mixed by a ball mill. The crushed and mixed raw material slurry is filled in a mold, and the pressure is adjusted to 8 while separating the solvent using a filter.
Pressure molding was performed at 00 kg / cm2. The wet-formed body was fired at 950 to 1200 ° C. Table 4 shows the properties of the obtained fired body.

From these results, it is possible to sufficiently increase the density and the hardness without performing the HIP treatment and eliminate the pores and the pits after the milling process by performing the wet molding.

[0045]

[Table 3]

[0046]

[Table 4]

When the sliding characteristics were examined in the same manner as in Example 1, the samples Nos. 11 to 15 of the present invention showed no damage to the disk or the head even when the CSS frequency was 30,000 times, and was excellent. It was confirmed that it exhibited sliding characteristics.

Example 3 A raw material having an average particle diameter of 3 μm was used as iron oxide, weighed so that the composition of the final sintered body was as shown in Table 5, and pulverized and mixed by a ball mill. The pulverized and mixed raw material was dried, passed through a 40 mesh and sized, and then granulated by adding paraffin wax as a binder. After the granulated powder was dry-formed, it was prefired at 950 to 1200 ° C for 2 hours in an oxidizing atmosphere. Table 6 shows the properties of the prefired body.

[0049]

[Table 5]

[0050]

[Table 6]

These pre-sintered bodies were HIPed at 950 to 1200 ° C. for 1 hour in an argon atmosphere. However, the sample having the average particle size of the raw material exceeding 1 μm (No. 1)
6, 17, 19, and 20) could not produce a dense sintered body having a relative density of 99% or more. On the other hand, the sample (No. 18) in which the average particle size of the raw material is 1 μm or less has a relative density of 99%.
% Or more.

From this, the average particle size of the pulverized raw material was 1 μm.
When a raw material exceeding m was used, the specific gravity of the pre-sintered body was low, the relative density was lower than 99%, and a dense pre-sintered body could not be obtained. For this reason, a dense sintered body could not be produced even by the HIP treatment.

[0053]

As described above, according to the present invention, 95.0 is obtained.
And 99.95 wt% Fe ₂ O _3, a main component of ZrO ₂ 0.05 to 5.0 wt%, from 0.5 to 0.01 parts by weight of Mn to these 100 parts by weight of the main component Comprising a sintered body of non-magnetic ceramics having a relative density of 9
By forming a slider for a magnetic head having a pore size of 9% or more and a pore size of 2 μm or less, pores do not occur, the pit size on a micromachined surface can be reduced, and damage to the medium and the head due to sliding of the magnetic head and the disk. It is possible to provide a material and a manufacturing method which are excellent in sliding characteristics with less friction. As a result, a lubricant, a magnetic powder or the like does not adhere to the magnetic head during CSS, so that destruction of recorded data and damage to the head can be reliably prevented, and the reliability of the magnetic recording apparatus can be significantly improved. In addition, thereby, the coefficient of thermal expansion becomes 106 to 108 × 10 ⁻⁷ / ° C., and Mn—Z
Since the thermal expansion coefficients of the n-type ferrite core and the composite core are substantially equal to each other, it is possible to achieve an effect that the glass and the core can be welded to each other.

Further, according to the present invention, after wet molding using a raw material powder having an average particle diameter of 1.0 μm or less consisting of Fe ₂ O ₃ powder, ZrO ₂ powder and MnO ₂ powder of 95% by weight or more, By baking in an oxidizing atmosphere, or by baking a dry-formed or dry-formed body by hot pressing or HIP processing, non-magnetic ceramics having few pores and small pits on a processing surface can be mass-produced at low cost. .

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein 95.0 to 99.95% by weight of Fe ₂ O is present.
₃ , 0.05 to 5.0% by weight of ZrO ₂ as a main component,
Mn is 0.5 to 0. 0 to 100 parts by weight of these main components.
It consists of a sintered body of non-magnetic ceramics containing 01 parts by weight ,
The relative density of the sintered body is 99% or more and the pore size is 2
μm or less, slider for a magnetic head
- 2. An Fe ₂ O ₃ powder of at least 95% by weight , ZrO ₂
A mold was filled with a slurry containing a raw material powder having an average particle diameter of 1.0 μm or less, which was composed of powder and MnO ₂ powder, and the solvent in the slurry filled in the mold was separated using a filter , followed by pressure molding. Then, the obtained molded body is hot pressed.
Or non-magnetic by firing by hot isostatic pressure treatment
Manufactures sliders for ceramic magnetic heads
A method for manufacturing a slider for a magnetic head .