JP3215000B2 - Non-magnetic ceramics for recording / reproducing head slider and method of manufacturing 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 used for a recording / reproducing head slider such as a magnetic head and a method for producing the same. The material itself has a high hardness and a high Young's modulus. Ceramics for a recording / reproducing head slider, which has a low frictional force and an attractive force with a recording disk, which is a high-density recording medium, as well as can provide a highly reliable information recording device that can manufacture a non-magnetic ceramics, and its manufacture It is about the method.

[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. 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, 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.

[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. However, the conventional alumina / titanium carbide composite material has a problem in that the amount of processing per unit time by ion milling is small, and the unevenness of the processed surface after ion milling is large. That is, in recent years, a material having a high processing speed by ion milling and a small processing surface unevenness has been required.

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 which has a small unevenness and has a small attraction force and a small frictional force with respect to a disk and is excellent in slidability and a method for producing the same.

[0012]

As a result of studying the above problems, the present inventor has found that in the case of a non-magnetic material for a head slider, by increasing the Young's modulus of the material itself, the bar material of the slider is reduced. Non-magnetic ceramics for the recording / reproducing head are composed of 3.6 to 10.1% by volume of titanium oxide and 96.4 to 89.9% by volume of alumina. By including rutile crystal phase as titanium oxide, precision processing is possible, grinding load is small, processing speed by ion milling is large, unevenness on micro-machined surface is small, frictional force and adsorption force with disk It has been found that a material having a small sliding property and excellent in sliding characteristics can be obtained, and the present invention has been achieved.

That is, the non-magnetic ceramic for a head slider for recording / reproducing according to the present invention comprises titanium oxide of 3.6 to 1 %.
And 0.1% by volume, the alumina from 96.4 to 89.9% by volume, or with respect to the main component of 100 parts by weight, there is a zirconia comprising 0.1 to 5 parts by weight, the body
Product specific resistance is 10 ¹⁰ Ωcm or more and titanium oxide
Has an average crystal grain size of 1 μm or less . Such non-magnetic ceramics include titanium oxide having an average particle size of 0.6 μm or less as a raw material in a range of 3.6 to 10.
A mixed powder containing 1 % by volume and 96.4 to 89.9 % by volume of alumina, or a molded product of this mixed powder was 1175 to 1175%.
Hot pressing at 1300 ° C. or the mixed powder,
Alternatively, the molded body of this mixed powder is heated at 1175 to 1300 ° C.
After the preliminary firing, hot isostatic pressure treatment is performed at 1000 to 1300 ° C., and then 800 to 1200 in an oxidizing atmosphere.
It is characterized in that it is heat-treated at ℃.

Here, the reason why the ratio of titanium oxide and alumina is limited to the above-mentioned ratio is mainly that the bar material for the slider or the flat sliding surface is processed with high precision. When the content is less than 0.6% by volume (when the content of alumina is more than 96.4% by volume), the effect of improving the sliding properties and sinterability by titanium oxide is reduced, and the strength and Young's modulus are reduced and the material is easily deformed. If titanium oxide exceeds 10.1% by volume (alumina is less than 89.1% by volume), the Young's modulus decreases, the deformation during processing of the bar material increases, and the floating surface of the slider increases. This is because it is difficult to accurately process the surface into a plane. Also, the milling surface roughness tends to be large.

The non-magnetic ceramic of the present invention is
It is desirable that zirconia be contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the main component composed of titanium oxide and alumina. This is because the addition of zirconia improves chipping characteristics during machining and improves flatness. This is because a smooth 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.
If the amount is less than 1 part by weight, the edge formed by diamond wheel processing or groove processing is easily chipped. If the amount is more than 5 parts by weight, the Young's modulus of the material tends to decrease, which is not preferable. It is. The amount of zirconia based on 100 parts by weight of the main component composed of titanium oxide and alumina is 3 to 5 parts by weight from the viewpoint of obtaining a flat sliding surface, and 0.1 to 3 parts by weight from the viewpoint of high Young's modulus. It is desirable to do.

[0016] The nonmagnetic ceramic of the present invention, it is necessary that the volume resistivity is 10 ¹⁰ [Omega] cm or more, which, when the volume resistivity is less than 10 ¹⁰ [Omega] cm is the conductive material This is because the current becomes closer and the current leaks. The volume resistivity is 1 × in terms of insulating material.
It is preferably at least 10 ¹¹ Ωcm, and more preferably at least 1 × 10 ¹² Ωcm from the viewpoint of preventing leakage current. In the non-magnetic ceramic of the present invention,
The average crystal grain size of titanium oxide in the sintered body is 1 μm
It is important that: This is because the surface roughness of the micromachined surface of the ion milling can be reduced. The average crystal grain size of titanium oxide is desirably 0.6 μm or less, and particularly desirably 0.3 μm or less.

Further, in the non-magnetic ceramics of the present invention, for example, the average particle size of the raw material is 0.6 μm or less (50% particle size by microtrack, where 50% particle size by microtrack is integrated with the particle size). In the graph of the volume fraction, the mixed powder containing titanium oxide and alumina having a cumulative volume fraction of 50%) is subjected to hot pressing or hot isostatic pressure treatment (HIP), or molding of the mixed powder. It can be obtained by subjecting the compact to hot pressing or hot isostatic pressure treatment, or subjecting the mixed powder to compacting and firing as described above to hot pressing or hot isostatic pressure treatment. 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 average particle size of the titanium oxide raw material is set to 0.6.
The reason why the diameter is not more than μm is that if the diameter is larger than 0.6 μm, the sintering temperature becomes high, so that the particle size of the alumina crystal becomes large,
This is because pores remain in the sintered body and it is difficult to remove the pores. Further, even if the sintered body is densified, the surface roughness Ra of the processed surface finely processed by ion milling is 1
This is because it becomes as large as 00 nm or more and is not suitable as, for example, a slider material. The raw material particle size of the titanium oxide is preferably 0.3 μm or less, particularly preferably 0.2 μm or less.

The reason why hot pressing or hot isostatic pressure treatment is employed for firing is that 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 50 to 500 kgf / cm ² , 117
Performed at 0.5 to 1300 ° C. for 0.5 to 1 hour. The hot isostatic pressure treatment was pre-baked at 1175 to 1300 ° C., and then the pressure was 500 to 2000 kgf in an argon or nitrogen atmosphere.
It is suitably performed at 1000-1300 ° C./cm ² for 1 hour.

In the present invention, after hot pressing or hot isostatic pressure treatment, 800 to 1 in an oxidizing atmosphere.
It is desirable to perform a heat treatment at 200 ° C., in order to increase the volume resistivity. Here, 800 to 12
The reason for the heat treatment at 00 ° C. is that if the temperature is lower than 800 ° C., the volume resistivity cannot be sufficiently increased.
This is because heat treatment at a temperature higher than 200 ° C. generates pores.

[0021]

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 is 2.19 × 10 ⁻⁴ ,
1.14 × 10 ⁻⁴ and 7.13 × 10 ⁻⁵ , indicating that the deformation becomes smaller as the Young's modulus increases. This indicates that a material having a higher Young's modulus can be processed into a surface having less deformation and a smaller flatness.

Therefore, the non-magnetic ceramics for a recording / reproducing head according to the present invention are suitable for alumina having a large Young's modulus.
By uniformly dispersing titanium oxide with excellent sliding properties, the Young's modulus of the material itself can be improved, and deformation during grinding with a diamond grindstone can be suppressed, and precision machining is possible. The load at the time of processing can be reduced, the processing speed by ion milling is high, the unevenness after processing is small, and the frictional force and suction force with the disk can be reduced.

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

Further, the raw material particle size of titanium oxide is set to 0.6 μm.
m (50% particle size by Microtrack), the temperature range during pre-firing before hot pressing or HIP processing can be set to a wide range of 1175 to 1300 ° C, and 95% or more. A pre-sintered body having a relative density is obtained, and the subsequent HIP processing becomes possible. In addition, by using such a titanium oxide having a raw material particle size of 0.6 μm or less, a composite material having a fine crystal particle size with an average crystal particle size of a sintered body of 1.0 μm or less can be produced. Raw material particle size of titanium oxide is 0.6μm
Above, the range of the pre-firing temperature is limited, and the relative density is 95%.
This is because it becomes difficult to obtain the above stable pre-sintered body. As the pre-firing temperature increases, the particle size of the titanium oxide crystal increases. When the temperature exceeds 1300 ° C., the titanium oxide reacts with alumina to synthesize aluminum titanate.
Since the hardness and the Young's modulus are reduced, it is necessary that aluminum titanate is not detected by X-ray diffraction measurement. Further, the pre-firing temperature is high or the raw material particle size is large and the average crystal particle size of titanium oxide of the sintered body is 1 μm.
The material having a diameter of m or more had a surface roughness Ra of a processed surface finely processed by ion milling as large as 100 nm or more, and was not suitable as a slider material.

In order to enhance the insulating properties of the slider, hot isostatic pressing (HIP) in an argon atmosphere is used.
It is desirable that the material produced by the carbon-type hot pressing has a small volume resistivity of 10 ⁴ Ωcm. Furthermore, if insulation is required, hot pressing or HIP
By subjecting the treated material to a heat treatment in an oxidizing atmosphere, the volume resistivity can be increased to 10 ¹⁰ Ωcm or more.

[0026]

【Example】

Example 1 A raw material having an average particle diameter of 0.6 μm as titanium oxide and a raw material having an average particle diameter of 0.44 μm as alumina were weighed such that the composition of the sintered body became as shown in Table 1, and pulverized and mixed using alumina balls as a medium. The mixed raw material is dried, passed through a 40 mesh and sized, and then filled in a carbon mold and filled with 350 kgf / cm.
^A hot pressing treatment was performed at a temperature of 1150 ° C. to 1300 ° C. by applying a pressing force of ² . Table 1 shows the characteristics of the sintered body.

[0027]

[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 that of the intensity measurement and using a pulse echo method. 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 volume resistivity is set to 3 mm × 4 mm × 4.
Apply silver paste to both ends of a 0 mm test piece and
It was measured by the terminal method. In addition, at the same time, in an oxidizing atmosphere, 110
The volume resistivity of the sample after the heat treatment at a temperature of 0 ° C. for 2 hours was measured. Further, the sample before the heat treatment was subjected to milling using an argon source of Kaufman-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 (TF700H) was simultaneously milled. The surface roughness used a Nanoscope 2 atomic force microscope (AFM) manufactured by Digital Instruments. The AFM has a probe tip curvature R10n made of silicon nitride manufactured by Olympus Corporation.
A probe of m to R 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 ceramic of the present invention has a strength of 509 MPa or more and a hardness of 15.3 GPa.
As described above, the Young's modulus is 385 GPa or more, there is no pore of 1 μm or more in the sintered body, and the milling speed is 100
It can be seen that the surface roughness is not less than A / min and that the milling surface has good characteristics. On the other hand, the conventional alumina-titanium carbide composite material has a high Young's modulus of 398 GPa, but has a large load during processing, a low milling speed, and a high milling surface roughness Ra.

Next, 1.6 × 2.2 ×
A slider having two rails of 0.9 mm in size was prepared, and a Haruna Tsushin CSS tester was used.
A test was conducted to evaluate the number of CSS times, disk damage, and head damage. The test method was performed by sliding a slider on the disk, the maximum rotation speed of the disk was 3600 rpm, and 3600 rpm from the stop.
The time at which m was reached was 5 seconds, and after holding at 3600 rpm for 3 seconds, the operation was stopped after 5 seconds and the stopped state was 5 seconds.
This operation was set to one CSS. As a result, the sample No.
In the case of the material No. 12, the number of CSSs was 30,000 times, which caused damage to the disk and the head.
It was confirmed that the sample No. 11 exhibited excellent sliding characteristics without damage to the disk or head even when the number of CSSs was 40,000.

Example 2 A raw material having an average particle size of 0.55 μm as titanium oxide and a raw material having an average particle size of 0.44 μm as alumina were weighed so that the composition of the sintered body was as shown in Table 2, and pulverized using alumina balls as a medium. Mixed. The mixed raw material was dried, sized through a 40 mesh, and then granulated by adding paraffin wax as a binder. And after molding this, 1175 ° C
From 1300 ° C. Table 2 shows the relative density calculated from the specific gravity and composition of the prefired body.

[0034]

[Table 2]

These pre-sintered bodies were subjected to HIP treatment at 1200 to 1300 ° C. for 1 hour in an argon atmosphere, and the density, hardness, strength, Young's modulus, presence / absence of pores, milling speed, milling surface roughness were obtained in the same manner as in Example 1. The degree and volume resistivity were measured and are shown in Table 2. The volume resistivity is a value after HIP and after heat treatment at 1100 ° C. for 2 hours in an oxidizing atmosphere in the same manner as in Example 1. In addition, the relative density after HIP of the samples 14 to 20 of the present invention was 99.5% or more, and it was a dense sintered body. Further, when the sliding characteristics of the sample before the heat treatment were examined in the same manner as in Example 1, the number of CSSs of Sample Nos. 14 to 20 was 40,000.
It was confirmed that there was no damage to the disk or head even after the rotation and excellent sliding characteristics were exhibited.

Comparative Example A raw material having an average particle size of 1.5 μm as titanium oxide and a raw material having an average particle size of 0.44 μm as alumina were weighed so that the composition of the sintered body became as shown in Table 3, and pulverized and mixed using alumina balls as a medium. The mixed raw material was dried, sized through a 40 mesh, and then granulated by adding paraffin wax as a binder. After molding, 1175 to 1 in an oxidizing atmosphere
Pre-baking was performed at 350 ° C. for 2 hours. Table 3 shows the relative density calculated from the specific gravity and composition of the prefired body.

[0037]

[Table 3]

These pre-sintered bodies were HIPed at 1200 to 1350 ° C. for 1 hour in an argon atmosphere. However, a dense sintered body having a relative density of 99% or more could not be produced. From this, the average particle size of titanium oxide is 1.5
It is understood that when a raw material of μm is used, a dense sintered body cannot be produced even by the HIP treatment.

[0039]

As described in detail above, in the non-magnetic ceramics for the recording / reproducing head slider of the present invention, the Young's modulus of the material itself can be increased, whereby the deformation at the time of processing is small and the floating surface is flat. The material can control the degree of precision with high precision, can perform fine processing, has a high processing speed, has small irregularities on the fine processing surface, has a small frictional force and suction force generated between the head and the disk, and has excellent sliding characteristics. Obtainable.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating the amount of deformation of a work when a load is applied to the work at the time of mirror finishing, calculated by a finite element method.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 5/31 C04B 35/00-35/22

Claims (3)

(57) [Claims] (1) 3.6 to 10.1 % by volume of titanium oxide;
Alumina consists of a 96.4 to 89.9% by volume, the volume
The specific resistance is 10 ¹⁰ Ωcm or more and the titanium oxide
Io, wherein the average crystal grain size is 1μm or less
Non-magnetic ceramics for recording / reproducing head sliders with excellent milling processability . 2. The composition according to claim 1, wherein said titanium oxide comprises 3.6 to 10.1 % by volume.
A main component comprising 96.4 to 89.9 % by volume of alumina, and 0.1 to 5 parts by weight of zirconia based on 100 parts by weight of the main component, and a volume resistivity of 10 ¹⁰ Ωcm
And the average crystal grain size of titanium oxide is 1 μm or less.
Excellent ion milling process characterized by being below
Non-magnetic ceramics for recording and reproducing head slider was. 3. Titanium oxide having an average particle diameter of 0.6 μm or less is 3.6 to 10.1 % by volume, and alumina is 96.4 to
Hot-pressing the mixed powder containing 89.9 % by volume or a molded body of this mixed powder at 1175 to 1300 ° C;
Alternatively, the mixed powder, or a molded product of the mixed powder is
1000-13 after pre-firing at 175-1300 ° C
Hot isostatic pressure treatment at 00 ° C., and then heat treatment at 800 to 1200 ° C. in an oxidizing atmosphere.
A method for producing non-magnetic ceramics for recording / reproducing head sliders having excellent ion milling properties .