JPH062616B2 - Ceramic material for magnetic head slider - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic material used particularly for a magnetic head slider.

2. Description of the Related Art Recently, a permalloy thin film having high magnetic permeability has been used as a head magnetic circuit constituent material of a magnetic head for high density recording. Ceramic materials are generally used as slider materials for such magnetic heads.
Good CS / S characteristics (abrasion resistance of slider sliding surface, etc.), dense structure, high hardness, cutting, grooving,
In each process such as mirror finishing, it is required to have excellent workability. As meeting such requirements, alumina - titanium carbide _{(A 2} O 3 -TiC) sintered body and the like.

For example, A ₂ O described in JP-A-55-163665
Obtained by firing a mixture of ₃ and TiC by a hot pressing method and used for a slider element of a flying magnetic head. A ₂ O ₃ and TiC described in JP-A-56-140066.
, Yttrium oxide (which may be included as a solid solution or a constituent of the composite) or yttrium carbide (which may be included as a double carbide or a constituent of the composite) in the form of hot Those obtained by the isobaric pressure (HIP) method, Al ₂ O ₃ and Ti described in JP-A-57-135772.
At least one free-cutting property-imparting agent selected from MgO, NiO, Cr ₂ O ₃ , and ZrO ₂ and Y ₂ O ₃ are added to C and TiO ₂ , and those obtained by the HIP method.

In addition to this, a method of adding Mo or W in the form of a single substance or a carbide and firing the mixture to obtain an A ₂ O ₃ —TiC sintered body can be mentioned.

Further, MgO described in JP-B-60-54266,
Aluminum oxide containing at least one or more of Y ₂ O ₃ , CrO ₃ and NiO and ZrO ₂ (average particle size of powder is 1 μm or less) and titanium carbide powder containing titanium carbonate powder (average particle size of powder is 1 μm or less). ) And sintering in a reducing atmosphere, JP-B-51-569
And those obtained by hot pressing the mixed powder of titanium carbide powder, titanium oxide powder, and alumina powder described in JP-A No. 53-14568.

However, A ₂ O ₃ -Ti obtained by the above method
All of the C sintered bodies have a problem in workability such that when the cutting processing speed is increased, the chipping occurrence rate is high, and the particles easily fall off, and also the particles easily fall off during mirror surface processing. In order to reduce the chipping occurrence rate, in the ceramic sintered body for the ceramic tool material, F
Although the group e metal is added in the form of a simple substance or an oxide, it becomes non-magnetic, and an undesirable situation occurs when it is used as a magnetic head slider material.

Therefore, we solve this _problem, A ₂ O 3 -Ti
The present inventors have proposed a C sintered body to which at least one oxide of Ga, Ba, Ce and Nb is added (Japanese Patent Application No. 59-278810).

However, even this one is not sufficient in terms of grain detachment particularly in the CS / S characteristics, and improvement in this point is desired.

II Object of the Invention The object of the present invention is to have particularly good CS / S characteristics, have a dense structure, have no particles falling off, have high hardness, are non-magnetic, and have excellent processability in each step. It is to provide a ceramic material useful for a magnetic head slider.

III DISCLOSURE OF THE INVENTION Such an object is achieved by the present invention described below.

That is, the present invention is based on 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina, and Ga, B
at least one of a, Ce and Nb oxides is 0.0
1 to 5 parts by weight and 0.01 to 5 parts by weight of an oxide of Ti are contained in the ceramic material for a magnetic head slider.

IV Specific Configuration of the Invention Hereinafter, the specific configuration of the present invention will be described in detail.

The ceramic material of the present invention is an alumina-titanium carbide sintered body.

The alumina-titanium carbide sintered body is a mixture of alumina (A ₂ O ₃ ) powder and titanium carbide (TiC) powder, and Ga,
It contains at least one selected from Ba, Ce and Nb oxides and an oxide of Ti.

Such an alumina-titanium carbide sintered body is generally obtained by adding a mixture of alumina (A ₂ O ₃ ) powder and titanium carbide (TiC) powder to an oxide of Ga, Ba, Ce, Nb (for example, GaO, CeO ₂ , Nb ₂ O ₅ or the like) or a compound which becomes an oxide by firing, for example, a powder of at least one compound selected from a carbonic acid compound (for example, BaCO ₃ or the like) and an oxide of Ti. It is added and fired.

Examples of the method for adding the Ti oxide or the like include (1) Ti oxides (TiO ₂ , TiO, Ti ₂ O)
₃ ) or a powder having at least a surface of a Ti oxide or a compound which becomes an oxide by firing, for example,
Alkoxide of Ti ([(CH ₃ ) ₂ CHO] ₄ Ti
Etc.) directly adding powder, (2) hot pressing the alumina-titanium carbide sintered body,
When firing by the hot isostatic pressing (HIP) method or the like, a method in which a part of titanium carbide is changed to Ti oxide or TiO ₂ by using an oxygen atmosphere can be mentioned.

These methods may be used alone or in combination.

Oxides of Ti, TiO ₂ is interposed between the _A 2 _{O 3} and TiC in _A 2 _O 3 -TiC sintered _A 2 _{O 3}
It is considered that it plays a role of strengthening the grain bond between TiC and TiC.

The A ₂ O ₃ powder is preferably pulverized, and the average particle diameter is preferably 0.1 to 1 μm, and particularly preferably 0.4 to 0.6 μm.

The TiC powder is preferably pulverized, and the average particle diameter is preferably 0.1 to 3 μm, particularly preferably 0.5 to 1.5 μm.

The mixing ratio of A ₂ O ₃ and TiC is such that A ₂ O ₃ is 60.
It is preferable that TiC occupy ˜95 wt% and correspondingly the remaining 40-5 wt%.

This is because if TiC is less than 5% by weight, the effect of adding TiC is small, and A ₂ O ₃ grains are likely to grow, and if it exceeds 40% by weight, workability is rapidly deteriorated.

Ga added to A ₂ O ₃ -TiC mixture, Ba, C
The average particle diameter of the powder of e, Nb oxide or carbonate compound is preferably 0.1 μm, and particularly preferably 0.5 to 1 μm.

Further, the addition amount is 0.01 to 10 parts by weight, particularly 1 to 7 parts by weight as an oxide, including an oxide and alkoxide of Ti and the like, relative to 100 parts by weight of the A ₂ O ₃ —TiC mixture. preferable.

That is, 0.01 to 5 parts by weight of Ti oxide and 0.01 to 5 parts by weight of at least one of Ga, Ba, Ce and Nb oxides are included.

This is because if the addition amount of these is less than 0.01 parts by weight, the effect of the present invention becomes ineffective, and if it exceeds 10 parts by weight, the uneven distribution of the additives in the sintered body increases rapidly.

When Ti oxide, alkoxide or the like is directly added to the A ₂ O ₃ —TiC mixture as powder, the average particle size of the powder of Ti oxide or alkoxide is 0.1 to 0.1
It is preferably 3 μm, particularly preferably 0.5 to 1.0 μm.

The content of Ti oxide in the material does not depend on the addition method,
The amount of the oxide is 0.01 to 5 parts by weight with respect to 100 parts by weight of the A ₂ O ₃ —TiC mixture, and is preferably 1 to 4 parts by weight, particularly preferably 2 to 3.5 parts by weight.

If the content is less than 0.01 parts by weight, A ₂ O ₃ and T
This is because the function of strengthening the grain bond with iC cannot be fulfilled, and when it exceeds 5 parts by weight, uneven distribution of TiO _{2 in} the sintered body increases.

To identify and quantify the above oxides, the ICP emission spectroscopic analysis method and the combustion infrared absorption method in an oxygen stream may be used.

The A ₂ O ₃ —TiC sintered body is usually a mixture of A ₂ O ₃ powder and TiC powder, powders of Ga, Ba, Ce, Nb oxides, carbonate compounds, and the like, as well as Ti oxides and alkoxides. It is obtained by adding and mixing the powder of 1. to form a molded body, sintering the molded body by a hot press sintering method in an oxygen atmosphere or a non-oxidizing atmosphere, and allowing it to cool.

The sintering temperature in this case is 1500 to 1800 ° C., especially 16
50-1750 degreeC is preferable.

If the temperature is lower than 1500 ° C., a dense sintered body cannot be obtained, and if the temperature is higher than 1800 ° C., the sublimation of the additive increases and the surface layer and the inside have a different structure.

The pressing pressure is about 200 to 300 kg / cm ² .

The non-oxidizing atmosphere may be an inert gas such as N ₂ , Ar, or He, H ₂ , CO, various hydrocarbons, or the like, a mixed atmosphere thereof, or a vacuum.

The sintering time is generally 1 to 3 hours.

Upon sintering, the green compact of the raw material powder is pre-sintered in an oxygen atmosphere or a non-oxidizing atmosphere (for example, vacuum up to 1200 ° C., then preferably Ar atmosphere), and then in a HIP furnace. A hot isotropic isostatic pressing (HIP) method of sintering the pre-sintered body may be used. The presintering temperature is preferably 1400 to 1650 ° C. and the time is preferably 1 to 3 hours. The temperature in the HIP method is 130
0-1500 ° C, sintering time 1-5 hours, pressure 100
It is 0 to 1500 kg / cm ² , and may be performed in an oxygen atmosphere or an inert atmosphere such as Ar.

In this case, oxygen gas, Ar gas, etc. should be kept at 300 to 40 at room temperature.
Pressurize to 0 kg / cm ² and then apply pressure by heating as above.

Whether the oxygen atmosphere or the non-oxidizing atmosphere is selected when performing the hot pressing method or the HIP method mainly depends on the addition method of the oxide of Ti.

When a powder of Ti oxide or alkoxide is directly added, a non-oxidizing atmosphere is preferable.

The non-oxidizing atmosphere is used to prevent the oxidation of TiC.

On the other hand, when it is necessary to convert TiC to Ti oxide during firing, it is preferable to use an oxygen atmosphere.

The added Ti oxides and alkoxides remain almost as oxides after sintering, regardless of the addition method.
As described above, the grain bond is strengthened.

Further, the added Ga, Ba, Ce and Nb oxides and carbonate compounds also remain almost as oxides after sintering, and Ti
Like the compound, it is thought to function to strengthen the grain bond.

It is confirmed by X-ray analysis that all of the compounds remain in the metallic state, because the bonded state is poor and cause the grains to fall out, and the favorable results are not obtained, but the sintered body of the present invention does not remain in the metallic state. ing.

The A ₂ O ₃ —TiC sintered body thus obtained is
While maintaining a high level of Vickers hardness, the strength is 9
Can be reduced from 5 kg / mm ² in 70~80kg / mm ^2, it is possible to include a cutting workability about twice.

In addition, it is less likely that particles will fall off during mirror finishing.

The ceramic material of the present invention described above is useful in various applications. Especially as a magnetic head slider material
_{The 2} O ₃ -TiC sintered body can be applied not only to a so-called flying type magnetic head substrate or slider, but also to a slider such as a floppy head and various dummy blocks.

According to the present invention, Ga, Ba, C are added to 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina.
Containing 0.01 to 5 parts by weight of at least one kind of e, Nb oxide and carbonic acid compound in the form of oxide, and 0.01 to 5 parts by weight of oxides of Ti and alkoxide in the form of oxide. Since it is added as described above, it is possible to obtain a ceramic material that has a dense structure, does not drop grains, has high hardness, is nonmagnetic, and has excellent workability in each step. As a magnetic head slider material, CS / S
The characteristics are also very good. Therefore, it is particularly expected to be used as a magnetic head slider material for high density recording.

VI Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown, and the effects of the present invention will be described in more detail.

Example 1 A ₂ O ₃ (purity 99.9%) powder having an average particle size of 0.5 μm and TiC (purity 99%, carbon content of 19% or more and 1% or less of which is free coquence) having an average particle size of 0.7 μm. Is)
Various additives (Table 1) were added at a ratio as shown in Table 1 to 100 parts by weight of and were mixed at a weight ratio of 7: 3, and wet mixing was performed by a ball mill for 20 hours. .

The mixed slurry was dry-granulated and filled in a black boat mold having an inner diameter of 77 mm. This in a vacuum atmosphere for 1 hour, sintering temperature 1
500-1800 ° C, press pressure 200-300 kg /
Hot press sintering was performed at cm ² .

After cooling, remove each sintered body from the mold,
The sample was processed with a diamond grindstone to prepare a sample (Table 1) having a diameter of 3 inches and a thickness of 4 mm.

A sample 301 containing no additive was also prepared in the same manner as above.

Samples 101-107, 201-211 and 30 above
No. 1 is shown in Table 1 of characteristics.

The method of evaluating the characteristics is as follows.

(1) Mirror Surface Machinability Each sample was lapped with green carbide (GC) abrasive grains, then polished with diamond abrasive grains, and the presence or absence of grains was examined by secondary electron image diffraction and a surface roughness meter.

Also, an X-ray image was obtained using an X-ray microanalyzer,
The surface was analyzed to examine the composition of the dropout part.

(2) Magnetism The presence or absence of magnetism was examined by a sample vibration type magnetometer (VSM).

(3) Cutting processability (a) Cutting property (constant pressure cutting experiment) Glass was adhered on a uniaxial thrust bearing, and a sample (width 30 mm, thickness 4 mm) was adhered thereon, and this sample was 500 g and 1000 g. The cutting speed at the time of pulling with a weight and cutting with a diamond cutting whetstone was measured.

(B) Chipping occurrence (constant speed cutting experiment) When cutting with a diamond cutting grindstone by constant speed feed (25 mm / min), the occurrence rate of chipping at a depth of 10 μm or more from the cut surface (width 30 mm, thickness 4 mm) Of the sample of 30 mm) with a microscope (20
0 times).

Five or less are represented by 0, 5 to 10 are represented by Δ, and more are represented by x.

(4) CS / S characteristics (a) Wear resistance Sample thin film elements are collectively formed and processed into a slider shape,
Contact start / stop for magnetic head 2
The degree of wear (μm) after repeated 10,000 times was examined.

(B) Grain loss (electrolytic evaluation) A voltage of 1 V was applied between the platinum and the sample, and the degree of TiC grain loss due to the electrolytic action was examined.

Rmax (index of surface roughness) of 100 Å or less is represented by ◯, 100 to 1000 Å is represented by Δ, and that exceeding 1000 Å is represented by x.

From Table 1, it can be seen that the samples of the present invention are excellent in all of mirror surface workability, cutting workability and CS / S characteristics. Further, it is also known that since it is non-magnetic and has good mirror surface workability, mirror surface processing of the slider sliding surface becomes easy, and it is suitable as a magnetic head slider material.

The sample of the present invention also had a high Vickers hardness.

Example 2 The A ₂ O ₃ powder and the TiC powder used in Example 1 were mixed in a weight ratio of 6.5: 3.5 and BaCO.
2% by weight of ₃ was added and the same treatment as in Example 1 was performed to prepare a sample.

However, the firing atmosphere is an oxygen atmosphere, the firing time is 1 hour, the sintering temperature is 1500 to 1800 ° C., and the pressing pressure is 2
It was set to 00 to 300 kg / cm ² .

In this case, 10% by weight of TiC was changed to Ti oxide.

The characteristics of this sample were evaluated in the same manner as in Example 1.

The results are shown below.

From the results, the effect of the present invention is clear.

Claims (2)

[Claims] 1. To 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina, 0.01 to 5 parts by weight of at least one oxide of Ga, Ba, Ce and Nb and Ti. A ceramic material for a magnetic head slider, which comprises 0.01 to 5 parts by weight of an oxide. 2. A compound selected from oxides of Ga, Ba, Ce and Nb and / or compounds which become these oxides by firing, per 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina. At least one kind and an oxide of Ti as 0.01 to
The ceramic material for a magnetic head slider according to claim 1, wherein the ceramic material is added so that 5 parts by weight is added and sintered.