JPH07315916A - Substrate material for thin film head - Google Patents

Abstract

PURPOSE:To obtain a substrate material for a thin film magnetic head having a small grain size, excellent in machinability and excellent in lubricity with a medium in spite of high hardness and high strength. CONSTITUTION:Powdery starting material consisting of >=10wt.% TiC and the balance Al2O3 is sintered with plasma by electric discharge or powdery starting material contg. at least one among Cr2O3, TiO2, Y2O3 and MgO by <=5wt.% base consisting of >=10wt.% TiC and the balance Al2O3 is sintered with plasma by electric discharge. The resultant sintered compact is used as t.he objective substrate material for a thin film magnetic head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate material for a magnetic head incorporated in a floppy disk drive or a hard disk drive which is a peripheral device of a computer, and more particularly to a non-magnetic substrate material for a thin film magnetic head.

[0002]

_2. Description of the Related Art Conventionally, Al ₂ O ₃ --TiC ceramics having high strength and good chemical resistance have been used as a substrate material of this type.

[0003]

However, this kind of Al ₂ O ₃ -TiC ceramics causes abrasion of the recording medium due to its high hardness. Since the sinterability is poor, the time required for the sintering step is 6 to 8 hours at a high temperature of 1700 to 1800 ° C. even when using a hot press in order to obtain a dense material required as a substrate material. .
Since it has poor machinability, it has a drawback in that it cannot meet the demand for miniaturization. The present invention has been made in order to eliminate these drawbacks, and an object of the present invention is to provide a substrate for a thin film magnetic head which is excellent in sinterability, machinability and lubricity with a medium and has little wear.

[0004]

The present invention is based on the conventional Al ₂ O ₃ composition.
-TiC ceramics without defects, 1) A
A substrate material for a thin film magnetic head made of a sintered body obtained by performing spark plasma sintering of a raw material powder made of l ₂ O ₃ —TiC and not containing a sintering aid, 2) a main material made of Al ₂ O ₃ —TiC It is a substrate material for a thin film magnetic head made of a sintered body obtained by spark plasma sintering a raw material powder in which at least one of Cr ₂ O ₃ , TiO ₂ , Y ₂ O ₃ and MgO is added to its components.

According to the present invention: 1) 10% by weight of TiC
Including the above, the substrate material for a thin film magnetic head consisting of the balance Al ₂ O ₃ , 2) Containing 10 wt% or more of TiC, the balance Al ₂ O ₃
100 parts by weight of the main component consisting of Cr ₂ O ₃ and TiO
A thin film magnetic head substrate material is obtained which contains 5 parts by weight or less of at least one of ₂ , Y ₂ O ₃ and MgO.

In the present invention, the composition range of TiC is limited because the Vickers hardness is 2000 when the content is less than 10 wt%.
This is because

Further, in the present invention, Cr ₂ O ₃ , Ti
The reason why the addition amount of O ₂ , Y ₂ O ₃ and MgO is limited to 5 wt% or less is that the grain growth effect becomes remarkable when it exceeds 5 wt%.
This is because chipping occurs during processing.

[0008]

In the present invention, the sintering is performed by the spark plasma sintering method. Spark plasma sintering is a kind of hot pressing, but by applying a high voltage pulse voltage while applying high pressure to the sintering raw material powder using a hydraulic press device, etc., Create a plasma discharge,
By utilizing the heat generation effect and the surface diffusion effect / volume diffusion effect, it is a method in which sintering is completed at a low temperature in a short time as compared with ordinary hot pressing. The substrate material obtained by the present sintering method can be mass-produced, is suppressed in grain growth, is dense, and is excellent in workability.

[0009]

EXAMPLES The present invention will be described in detail below with reference to examples. A with an average particle size of 0.1 to 0.3 μm and a purity of 99% or more
l ₂ O ₃ , TiC, Cr ₂ O ₃ , TiO ₂ , Y ₂ O ₃ , MgO
Each powder raw material of was weighed so that the composition ratio shown in Table 1 was obtained,
The samples No. 1 to No. 13 were used. Each sample was weighed so as to have a predetermined composition, and ethanol was used as a solvent and mixed in a ball mill for 20 to 40 hours. This was filtered, dried, and then sized to prepare a raw material powder. In the table, A in the column of composition indicates the main component, and Al ₂ O ₃ and TiC
The total weight of Al ₂ O ₃ and TiC is 100% by weight. In addition, B represents wt% of the additive B with respect to A when A is 100 parts by weight.

[0010]

[Table 1]

Next, the obtained powder is filled in a mold made of graphite carbon, and the temperature is set to 1500 ° C. for 5 minutes to obtain 500.
Spark plasma sintering is performed at a pressure of kg / cm ² and φ60
A disc-shaped sample having a size of mm × 6 mm was prepared.

As the evaluation of the material properties of the sample obtained by the above steps, the relative density by the Archimedes method, SEM
The crystal grain size, Vickers hardness, and bending strength (F) by the three-point bending method were measured.

From each disk-shaped sample, 5 × 5 × 10 m
After cutting out m prisms, these prisms are adjacent to each other 5 ×
2 x 2 μm generated on the ridge by mirror-finishing 2 faces of 10 mm
The above chipping number was counted and converted into the occurrence rate per cm, and the workability was evaluated.

Further, a practical head-shaped chip was cut from each sample, brought into contact with a metal-based medium at a constant pressure and slid at 3600 rpm for a certain period of time, and then the weight reduction amount of the medium was measured. Then, the slidability was evaluated. In addition,
Evaluation is 1700 by the normal hot press of No.13.
Relative evaluation was performed by setting the value of the Al ₂ O ₃ —TiC material obtained by sintering at ℃ × 2 hours as 100.

The above results are summarized in Table 2. The sample No. in Table 2 corresponds to the sample No. and composition in Table 1.

[0016]

[Table 2]

Sample Nos. 1 to 10 are examples of the present invention, and sample Nos. 11 to 13 are comparative examples. Especially sample No.13
Is a sample sintered by conventional hot pressing.

Samples No. 1 to 10 of the present invention and No. 13
From the comparison with, the content of TiC is 10 wt% or more, and the balance is Al ₂
The sample made of O ₃ has a smaller crystal grain size and a smaller amount of wear of the medium in the wear test than the sample (No. 13) obtained by the conventional hot pressing. Further, despite the fact that spark plasma sintering is performed at 1500 ° C., which is 200 ° C. lower than that of conventional hot pressing, the relative density is as high as 99.6 to 99.98%, the Vickers hardness is high, and the chipping occurrence rate is also improved. You can see that

No. 10 and No. 13 in the example of the present invention.
Comparing with No. 10, it can be seen that No. 10 has almost the same density, Vickers hardness, and chipping occurrence rate as No. 13 containing the sintering aid, although it does not contain the sintering aid.

The example of the present invention and No. containing 5 wt% of TiC.
Comparing No. 11 with each other, it can be seen that when TiC is small, Vickers hardness is small and bending strength is also small.

Cr ₂ O ₃ , TiO ₂ , Y ₂ as sintering aids
No. 12 in which the addition amount of O ₃ and MgO exceeds 5 wt%
When the addition amount exceeds 5 wt%, the crystal grain size becomes coarse,
It also shows that the chipping occurrence rate increases.

In summary, 1) 10 wt% TiC
% Or more, and the remaining raw material powder consisting of Al ₂ O ₃ is subjected to spark plasma sintering to obtain a substrate material for a thin film magnetic head equivalent to the conventional one without adding a sintering aid,
2) Cr ₂ O ₃ , TiO ₂ , Y _{2 with} respect to 100 parts by weight of the main component containing 10% by weight or more of TiC and the balance Al ₂ O _3.
Despite high strength and high hardness, excellent lubricity with the medium and good machinability can be obtained by spark plasma sintering a raw material powder containing one or more of O ₃ and MgO in an amount of 5 wt% or less. It was found that a substrate material for a high density thin film magnetic head can be obtained.

[0023]

As is clear from the above results, according to the present invention, a substrate material for a thin film magnetic head equivalent to the conventional one can be obtained although 1) it does not contain a sintering aid. 2) Small particle size, excellent machinability, high hardness and high strength
A substrate material for a thin film magnetic head having excellent lubricity with a medium can be obtained.

Claims (2)

[Claims] 1. A TiC content of 10 wt% or more, with the balance being Al.
_A substrate material for a thin film head, which is obtained by spark plasma sintering a raw material powder of ₂ O ₃ . 2. The content of TiC is 10 wt% or more, and the balance is Al.
Relative to 100 parts by weight of the main component consisting of _{2 O 3, Cr 2 O 3} , T
A substrate material for a thin film head, which is obtained by spark plasma sintering a raw material powder containing at least 5 parts by weight of at least one of iO ₂ , Y ₂ O ₃ and MgO.