JP3121979B2 - Non-magnetic ceramics for recording / reproducing head and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic ceramic for a recording / reproducing head used for a ceramic substrate for a thin film magnetic head, a slider for various magnetic heads, a spacer for a magnetic head, a tape guide for magnetic recording, and the like. It is related to the manufacturing method, the material itself has a large hardness,
Since it has a Young's modulus, a head with high processing accuracy can be manufactured, and a highly reliable information recording device can be provided. In addition, frictional force and suction force with recording disks and recording tapes, which are high-density recording media, can be provided. And a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, high-density magnetic recording has made rapid progress. However, 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. As a recording / reproducing magnetic head, a thin film head suitable for increasing the density of magnetic recording using a magnetic thin film has attracted attention instead of a magnetic head using a conventional ferrite or the like.

[0003] A thin film head using a magnetic thin film is manufactured, for example, as follows. First, after an alumina sputtered film is formed as an insulating film on the surface of a substrate having a diameter of 6 inches to 3 inches, thousands of transducers are formed on the upper surface of the alumina film by using a lithography technique. An insulating alumina film is formed again on the substrate on which the transducer has been formed. The magnetic head is obtained by cutting individual magnetic heads from the substrate in consideration of the polishing allowance as a slider. After cutting out the bar material including the individual thin film heads, one surface of the bar material is polished as a sliding surface.

In recent years, as the recording density of a Winchester-type magnetic head has been improved, the flying height of the magnetic head from the disk surface has been reduced to submicron or less. The flying height of the slider changes from the difference. 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 has been proposed to stabilize the flying height of the head between the inner and outer circumferences.

[0005] Therefore, for the above reason, after polishing the sliding surface, which is one surface of the bar material cut out from the substrate,
A groove (recess) is formed on this sliding surface. This groove is generally machined. However, when a negative pressure slider having a groove of several μm is formed, milling by an ion beam, reactive ion milling, chemical etching, or the like is performed.

[0006]

In the conventional thin film head, a warp of several microns per 50 mm in length is generated in the slider bar during the above-mentioned cutting, and the magnetic gap depth (throat height) on the sliding surface is generated. Although the change of the thickness was also several microns, the influence on the electrical characteristics related to the read / write was small.

However, in magnetic heads for high-density recording, variations in gap depth due to the warpage cause a decrease in electrical characteristics. Therefore, the warpage in the state where the slider bar material is cut out needs to be submicron or less per 50 mm length. For magnetic heads for high-density recording, etc., alumina / titanium carbide-based materials have conventionally been used as slider materials.
Although the warpage of the slider bar material cut can be reduced to some extent, the load at the time of cutting with a diamond grindstone is large, and there is a problem that it is difficult to cut accurately in a short time. Was.

Further, when forming grooves in the slider bar material, it is necessary to finely process the sliding surface by ion milling or the like. However, from the viewpoint of mass production and accuracy, the processing time and the uniformity of the processed surface are required. Is an important characteristic in manufacturing. But,
The conventional alumina / titanium carbide composite material has a problem that the amount of processing per unit time by ion milling is small, and that the processed surface after ion milling has large irregularities. That is, in recent years, the processing speed by ion milling is high,
There is a demand for a material having a small unevenness on the processing surface.

In addition, the conventional slider material for a thin film head made of alumina and titanium carbide has a large attraction force and frictional force with a disk, causing a head crash or the like, and significantly reducing the reliability of an information recording apparatus. There was a problem. In order to enhance the reliability of the magnetic head, a material having a small frictional force and an attractive force generated between the magnetic head and the disk and having excellent sliding characteristics has been required.

In order to reduce the frictional force and the attraction between the recording disk and the recording or reproducing head, it has been proposed to form a crown or the like on the flying surface of the head to reduce the attraction. However, the size of this crown is several nanometers.
It is necessary to increase the precision of the apparatus, and this has made mass production of inexpensive heads difficult.

According to the present invention, deformation of grinding by a diamond grindstone or the like can be suppressed, precision processing can be performed, the load at the time of grinding is small, and the amount of processing per minute in fine processing by ion milling or the like is large. It is an object of the present invention to provide a non-magnetic ceramic having a small unevenness, a small attraction force and a low frictional force with a disk, and excellent slidability, and a method for producing the same.

[0012]

Means for Solving the Problems The present inventor has studied the above problems, and as a result, in the non-magnetic material for the head,
By increasing the Young's modulus of the material itself, deformation during processing of the slider bar material can be suppressed. The non-magnetic ceramic for the recording / reproducing head is made of 43 to 95% by volume of silicon carbide, ~ 57 % by volume
By setting the Young's modulus to 400 GPa or more , precision processing is possible, and the grinding load is small.
The present inventors have found that a processing speed by ion milling is high, irregularities on a finely processed surface are small, and a material having a small attraction force and frictional force with a disk and excellent in sliding characteristics can be obtained, and the present invention has been achieved.

[0013] That is, the non-magnetic ceramic of the present invention comprises a silicon carbide 43 to 95 vol%, and the alumina 5-57% by volume, but the Young's modulus is not less than 400 GPa, the silicon carbide 43-95 and volume%, alumina 5-5
A main component consisting of 7% by volume, relative to the 100 parts by weight of the main component, zirconia containing 0.1 to 5 parts by weight, Yan
It is desirable that the switching rate be 400 GPa or more . This non-magnetic ceramic contains 43 to 95% by volume of silicon carbide having an average particle diameter of 1 μm or less as a raw material, and has an average particle diameter of 0.2 to 1 μm.
It is produced by hot pressing or hot isostatic pressing a mixed powder containing 5 to 57 % by volume of alumina, a compact of this mixed powder, or a sintered body of the mixed powder.

Here, the reason why silicon carbide and alumina are limited to the above ratios is that when silicon carbide is less than 43 % by volume (alumina is more than 57 % by volume), the Young's modulus becomes 400 GPa or less, This is because it is difficult to accurately process the air bearing surface into a flat surface. When silicon carbide exceeds 95% by volume (alumina is 5% by volume)
This is because it becomes difficult to densify the sintered body. In particular, from the viewpoint of high Young's modulus, it is desirable that silicon carbide contains 43 to 95% by volume and alumina contains 5 to 57% by volume. From the viewpoint of densification, silicon carbide contains 43 to 95% by volume.
60 vol%, alumina desirably contains 57 to 40 vol%.

The non-magnetic ceramic of the present invention is
It is desirable to contain 0.1 to 5 parts by weight of zirconia with respect to 100 parts by weight of the main component consisting of silicon carbide and alumina, but this improves chipping characteristics during machining by adding zirconia, This is because a flat sliding surface can be obtained. Here, the reason that zirconia is contained in an amount of 0.1 to 5 parts by weight with respect to the main component is that zirconia is 0.1% by weight.
When the amount is less than 1 part by weight, the edge portion formed by diamond wheel processing or groove processing is easily chipped, and when the amount is more than 5 parts by weight, the Young's modulus of the material tends to decrease, which is not preferable. Because. The amount of zirconia based on 100 parts by weight of the main component consisting of silicon carbide and alumina is preferably 3 to 5 parts by weight from the viewpoint of chipping resistance and 0.1 to 3 parts by weight from the viewpoint of high Young's modulus. .

The non-magnetic ceramic of the present invention preferably has a Young's modulus of 410 GPa or more. This is because when the Young's modulus is less than 410 GPa, for example, the deformation during processing such as cutting out the slider bar material tends to increase.

It is particularly desirable that the Young's modulus is 420 GPa or more.

The nonmagnetic ceramic of the present invention contains alumina and silicon carbide as main components, but may contain mullite in addition to zirconia.

In the non-magnetic ceramic of the present invention, for example, the average particle diameter of the raw material is 1 μm or less (50% particle diameter by Microtrack, here 50% by Microtrack).
% Particle diameter is a particle diameter and an integrated volume fraction in a graph of 50% of an integrated volume fraction) of a mixed powder containing silicon carbide and alumina in a hot press or hot isostatic pressure treatment (HIP). Or hot pressing or hot isostatic pressing of the compact of the mixed powder, or hot pressing or hot isostatic pressing of the sintered compact formed and fired as described above. It can be obtained by: Of these, it is particularly desirable to subject the pre-sintered body produced by a vacuum firing furnace, an oxidizing atmosphere firing furnace, or the like to hot isostatic pressure treatment.

The reason why the average particle size of the silicon carbide raw material is set to 1 μm or less is that if the average particle size is larger than 1 μm, the sintering temperature becomes high, so that the particle size of the alumina crystal becomes large and pores are formed in the sintered body. This is because it remains and it is difficult to remove it. Further, even if the sintered body is densified, the surface roughness Ra of the processed surface finely processed by ion milling becomes as large as 100 nm or more, which is not suitable as a slider material, for example. It is desirable that the raw material particle size of this silicon carbide is 0.3 μm or less.

The average particle size of the alumina raw material is a standard one, but is generally 0.2 to 1 μm. In addition, hot pressing or hot isostatic pressure treatment is used for firing because pores of 1 μm or more in the sintered body can be removed. Hot pressing is performed in a carbon mold at a pressure of 100 to 500 kgf / cm ² , 1700 to 2000 kg.
C. for 0.5 to 2 hours and hot isostatic pressure treatment in an argon or nitrogen atmosphere at a pressure of 500 to 2000 kgf.
It is suitably performed at 1550-1900 ° C./cm ² for 1 hour.

[0022]

When the flying surface of the slider is mirror-finished, the flatness of the flying surface facing the disk needs to be strictly controlled in accordance with a decrease in the flying height. FIG. 1 shows a schematic diagram in which the amount of deformation of a work in a state where a load is applied to the work during mirror polishing is calculated by the finite element method. In such a state, when the work fixing jig is fixed with, for example, an adhesive, a force of f acts on the end portion due to the effect of the adhesive. still,
The work shape is 4mm x 1.3mm x 2.5mm,
The load was 1.0 kgf. And the Young's modulus is 130
00 kgf / mm ² , 25000 kgf / mm ² , 40
As a result of calculation for materials different from 000 kgf / mm ² , the deformation amount Δx of the work was 2.19 × 10 ⁻⁴ m.
m, 1.14 × 10 ⁻⁴ mm and 7.13 × 10 ⁻⁵ mm, and it can be seen that the deformation becomes smaller as the Young's modulus increases.

Accordingly, it is understood from this that a material having a higher Young's modulus can be processed into a surface having less deformation and a better flatness. Therefore, non-magnetic ceramics having a high Young's modulus can be manufactured by using alumina having a large Young's modulus as a main component and uniformly dispersing silicon carbide having excellent sliding properties in the alumina. By carefully selecting the firing conditions and raw materials to obtain such a large Young's modulus, a silicon carbide / alumina composite material for a recording / reproducing head, which has conventionally been difficult to densify, can be produced.

The non-magnetic ceramic for a recording / reproducing head according to the present invention improves the Young's modulus of the material itself by dispersing SiC having excellent sliding characteristics in alumina having a high Young's modulus, and grinds the material with a diamond grindstone or the like. In addition to suppressing deformation during processing, precision processing is possible and the load during grinding is reduced, the processing speed by ion milling is large, unevenness after processing is small, and
It is possible to reduce the frictional force and the attraction force with the disk.

Further, by adding zirconia to the main component consisting of silicon carbide and alumina, it is possible to improve the chipping characteristics at the time of machining and to improve the surface roughness after machining.

[0026]

【Example】

Example 1 A silicon carbide raw material powder having an average particle size of 0.4 μm and an alumina raw material powder having an average particle size of 0.2 μm
And crushed and mixed using alumina balls as a medium. Incidentally, the average particle size is 5 according to Microtrack.
0% particle size.

The mixed raw material powder is dried, passed through a 40 mesh and sized, and then filled in a carbon mold to obtain a powder of 350 kgf /
A pressing force of 1 cm ² was applied and hot pressing was performed at 1800 ° C. for 0.5 hour. Table 1 shows the characteristics of the sintered body.

[0028]

[Table 1]

Here, the density was measured by the Archimedes method, and the hardness was measured by using a hardness meter of AVK (manufactured by Akashi Seisakusho). The measurement condition is 20kgf load with Vickers indenter
Was added for 15 seconds, and then measured from the size of the indentation by the indenter. The strength was measured by preparing a test piece having a cross section of 3 mm × 4 mm, and measuring the strength by a three-point bending test method with a span of 30 mm. The head speed at this time is 0.5 mm / mi.
n. The Young's modulus was measured by preparing a sample having the same shape as the strength measurement, applying a load by three-point bending, and measuring the amount of deformation and the slope of the load value. The presence or absence of pores was determined by polishing using a 1 μm diamond abrasive grain, and then observing the polished surface with a scanning electron microscope to determine the presence or absence of pores of 1 μm or more.

Next, the sample was subjected to milling using an argon source of a Kauffman-type Miratron (manufactured by Commonwealth), and the milling speed and milling surface roughness were determined. The acceleration voltage was 800 V, and an argon beam was applied from an angle of 45 degrees with the normal to the processed surface of the sample. For comparison, an alumina-titanium carbide composite material (TF700
H) was simultaneously milled. The surface roughness used a Nanoscope 2 atomic force microscope (AFM) manufactured by Digital Instruments. For the AFM, a probe made of silicon nitride manufactured by Olympus Corporation and having a tip curvature R of 10 to 30 nm was used. The measurement visual field was 10 μm square. The milling speed was measured by measuring the step between the milled surface and the covered surface using a surface roughness meter.

According to Table 1, the nonmagnetic ceramics of the present invention (samples Nos. 2 to 11) have a Young's modulus of 400 GPa or more, and no pores of 1 μm or more exist in the sintered body.
It can be seen that the milling speed is 110 A / min or more and the milling surface roughness Ra is 68 or less, which is a good characteristic. On the other hand, the conventional alumina-titanium carbide composite material (sample No. 13) has a high Young's modulus of 398 GPa, but has a large processing load, a low milling speed, and a large milling surface roughness Ra. I understand.

Next, samples Nos. 2 to 11 in Table 1 and No. 1
Material No. 3 was made into a slider shape having two rails of 1.6 × 2.2 × 0.9 mm in size, and using a CSS tester manufactured by Haruna Tsushin Co., Ltd. A test was performed to evaluate the damage. The test was performed by sliding a slider over the disk, and the maximum rotational speed of the disk was set to 3600 r.
pm, 3600 rpm from the time of the stop was 5 seconds, and held at 3600 rpm for 3 seconds, stopped after 5 seconds, this stopped state was held for 5 seconds, and a series of these operations was performed once CSS times. As a result, the material No. 13 causes damage to the disk or head after 30,000 times, whereas the composite materials Nos. 2 to 11 of the present invention show excellent sliding characteristics without damage even after 30,000 times. There was found.

Example 2 A silicon carbide raw material powder having an average particle size of 1.0 μm and an alumina raw material powder having an average particle size of 0.2 μm
And then pulverized and mixed using alumina balls as a medium, then molded at a pressure of 1 ton / cm ² and
Pre-baking was performed at 00 ° C. for 2 hours. Pre-fired body at 1700 ° C
And a hot isostatic pressure treatment for 1 hour. The properties, milling speed and surface roughness of the sintered body were measured in the same manner as in Example 1, and the results are shown in Table 2.

[0034]

[Table 2]

According to Table 2, the samples Nos. 14 to 2 of the present invention were obtained.
At 0, the Young's modulus is large, no pores of 1 μm or more are present in the sintered body, the milling speed is high, and the milled surface roughness has good characteristics. Example 1
When the sliding characteristics were examined in the same manner as in
In No. 20, it was confirmed that even if the number of CSSs was 30,000, there was no damage on the disk or the head, and that excellent sliding characteristics were exhibited.

Example 3 A raw material having the composition shown in Table 1 of Example 1 was molded at a pressure of 1 ton / cm ² , and was prefired at 1000 ° C. for 2 hours. The prefired body was subjected to hot isostatic pressure treatment at 1700 ° C. at a pressure of 2000 atm for 1 hour. The properties, milling speed and surface roughness of the sintered body were measured in the same manner as in Example 1, and the results were shown in Table 3.
It writes in.

[0037]

[Table 3]

From Table 3, it can be seen that even when hot isostatic pressure treatment is performed, the Young's modulus is 410 GPa or more, no pores of 1 μm or more exist in the sintered body, and the milling speed is 110 A.
/ Min or more, and the milling surface roughness also has good characteristics.

Further, when the sliding characteristics were examined in the same manner as in Example 1, the number of CSSs was 3 in Sample Nos. 23 to 30.
It was confirmed that there was no damage to the disk or the head even after 0000 times, and that the sample exhibited excellent sliding characteristics.

Comparative Example A raw material having an average particle size of 1.5 μm as a silicon carbide powder having a composition of 8 and a raw material of 0.5 μm as an alumina were pulverized and mixed using alumina balls as a medium, and fired in the same manner as in Example 1. The sintered body had pores of 1 μm or more, and the same sliding test as in Example 1 was carried out.
When the number of SS was 300, the disk was damaged.

[0041]

According to the non-magnetic ceramics of the present invention, the Young's modulus of the material itself can be increased, whereby the deformation during processing is small, the flatness of the floating surface can be controlled with high accuracy, and fine processing can be performed. Thus, a material having a high processing speed, a small unevenness on a finely processed surface, a small frictional force or a suction force generated between the head and the disk, and excellent sliding characteristics can be obtained. Thereby, for example, a non-magnetic ceramic for a recording / reproducing head which is optimal for a ceramic substrate for a thin-film magnetic head, a slider for various magnetic heads, a spacer for a magnetic head, a guide for a magnetic tape, etc. can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a calculated amount of deformation of a work under a state where a load is applied to the work during mirror polishing by a finite element method.

Claims (3)

(57) [Claims] 1. A method according to claim 1, comprising 43 to 95% by volume of silicon carbide and 5 to 57 % by volume of alumina, and having a Young's modulus of 400 GPa.
Non-magnetic ceramics for a recording / reproducing head characterized by the above . 2. A main component comprising 43 to 95% by volume of silicon carbide and 5 to 57 % by volume of alumina.
A non-magnetic ceramic for a recording / reproducing head, comprising 0.1 to 5 parts by weight of zirconia with respect to 0 parts by weight and having a Young's modulus of 400 GPa or more . 3. The method according to claim 1, wherein the silicon carbide having an average particle diameter of 1 μm or less is 43 to
95 volume%, alumina having an average particle size of 0.2 to 1 μm
A method for producing a non-magnetic ceramic for a recording / reproducing head, comprising subjecting a mixed powder containing from 57 to 57 % by volume, a molded product of the mixed powder, or a sintered body of the mixed powder to hot pressing or hot isostatic pressure treatment. .