JPH062617B2 - 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. An alumina-titanium carbide (Al ₂ O ₃ —TiC) sintered body is mentioned as one satisfying such requirements.

For example, Al ₂ O ₃ described in JP-A-55-163665.
Obtained by firing a mixture of TiO2 and TiC by a hot pressing method and used for a slider element of a flying magnetic head. Al ₂ O ₃ and TiC described in JP-A-56-140066.
, Yttrium oxide (which may be included as a constituent of a solid solution or a composite) or yttrium carbide (which may be included as a constituent of a double carbide or a composite), and hot Those obtained by the isobaric pressure (HIP) method, Al ₂ O ₃ , TiC described in JP-A-57-135772
Further, 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 TiO ₂ and the compound is obtained by the HIP method.

In addition to this, a method of adding Mo or W in the form of a simple substance or a carbide and firing the mixture to obtain an Al ₂ O ₃ —TiC sintered body can also 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). ) Are mixed with each other and sintered in a reducing atmosphere, titanium carbide powders described in JP-B Nos. 51-569 and 53-14568,
Examples thereof include those obtained by hot pressing a mixed powder of titanium oxide powder and alumina powder.

However, Al ₂ O ₃ -TiC obtained by the above method
When the cutting speed is high, the rate of chipping is high and the particles easily fall out of the sintered body.
There is still a problem in workability such that grains are likely to come off during mirror finishing. In order to reduce the chipping occurrence rate, in the ceramic sintered body for the ceramic tool material, the Fe group metal is added in the form of a simple substance or an oxide, but when it is used as a magnetic head slider material, it becomes non-magnetic. An unfavorable situation occurs.

Therefore, Al ₂ O ₃ -TiC, which has solved such a problem,
The present inventors have proposed a 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 workability, reliability, and CS / S characteristics particularly when manufacturing a magnetic head slider, and improvement of this point is desired.

II Object of the invention The object of the present invention is, in particular, there is no grain shedding, very good workability, having a dense structure, high hardness, non-magnetic,
(EN) A ceramic material useful for a magnetic head slider having high reliability and CS / S characteristics.

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

That is, the first invention of the present invention is a ceramic material containing 5 to 40% by weight of titanium carbide in a mixture containing titanium carbide and alumina, wherein the average particle size of titanium carbide in the sintered body is 1 It is a ceramic material characterized by having a particle size of 0.1 to 2.5 μm and a titanium carbide particle size of 0.1 μm or less in an amount of 10% by weight or less.

Moreover, 2nd invention has Ga, B with respect to 100 weight part of mixture containing 5-40 weight% titanium carbide and alumina.
A ceramic material containing 0.01 to 10 parts by weight of at least one oxide of a, Ce, Nb and Ti, wherein the average particle diameter of titanium carbide in the sintered body is 1.0 to 2.5 μm. Of the titanium carbide, a ceramic material having a particle size of 0.1 μm or less is 10% by weight or less.

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 average particle size of titanium carbide (TiC) in the sintered body is 1.0 to 2.5 μm, preferably 1.5 to 2.0 μm.
m.

This is because if the average grain size of TiC in the sintered body is less than 1.0 μm, the workability is very poor, and if it exceeds 2.5 μm, the strength is reduced.

The particle size distribution of TiC is such that TiC having a particle size of 0.5 to 2.0 μm accounts for 80% or more of the total number of TiC particles. This measurement may be performed by using an electron microscope photograph or the like.

Further, TiC in the sintered body having a particle size of 0.1 μm or less is 10% by weight or less, and more preferably 10% of the total number.
It is preferably from 0 to 0 below. This is because TiC having a grain size of 0.1 μm or less has a high surface activity and causes a defect particularly in the reliability test and CS / S characteristics when used as a slider.

The alumina-titanium carbide sintered body is alumina (Al ₂ O ₃ )
And a mixture of titanium carbide (TiC) powder, preferably Ga, Ba, C
It contains at least one selected from oxides of e, Nb, and Ti.

Such an alumina-titanium carbide sintered body is generally, preferably, Ga, B in addition to a mixture of alumina (Al ₂ O ₃ ) powder and titanium carbide (TiC) powder.
an oxide of a, 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 carbonate compound (for example, BaCO ₃ , CaCo ₃ , S)
(rCO ₃ etc.) compound powder, and at least one selected from oxides of Ti are added and fired.

As a method of adding the oxide of Ti, etc., (1) oxide of Ti (TiO ₂ , TiO, Ti ₂ O ₃ etc.)
Powder or a powder of which at least the surface is an oxide of Ti, or a compound which becomes an oxide by firing, for example, Ti
Alkoxide ([(CH ₃ ) ₂ CHO] ₄ Ti, etc.) powder is directly added, (2) alumina-titanium carbide sintered body is hot-pressed,
When firing by a 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.

The oxide of Ti, TiO _2, is present in the Al ₂ O ₃ —TiC sintered body between Al ₂ O ₃ and TiC, and Al ₂ O ₃ and Ti
It is considered to play a role of strengthening the grain bond with C.

The Al 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 Al ₂ O ₃ and TiC is 60 to 9 for Al ₂ O ₃ .
It is preferable that TiC occupy 5% by weight, and TiC occupies the remaining 40 to 5% by weight.

This is because if TiC is less than 5% by weight, the effect of adding TiC is small and Al ₂ O ₃ also tends to grow grains, and if it exceeds 40% by weight, the workability sharply deteriorates.

Ga, Ba, Ce, added to the Al ₂ O ₃ -TiC mixture
The average particle size of the powder of Nb oxide, carbonic acid compound, etc. is 0.
It is preferably 1 to 3 μm, and particularly preferably 0.5 to 1 μm.

The addition amount is preferably 0.01 to 10 parts by weight, particularly 1 to 7 parts by weight, based on 100 parts by weight of the Al ₂ O ₃ —TiC mixture.

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.

In this case, 0.01 to 5 parts by weight of at least one of Ga, Ba, Ce and Nb oxides, or 0.01 to 5 parts by weight of Ti oxide may be contained. It is desirable to contain 0.01 to 5 parts by weight.

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

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 Al ₂ O ₃ —TiC sintered body is usually a mixture of Al ₂ O ₃ powder and TiC powder, preferably Ga, B.
Hot pressing sintering in an oxygen atmosphere or a non-oxidizing atmosphere after adding and mixing powders of oxides or carbonates of a, Ce, Nb or powders of oxides of Ti or alkoxide This molded body is sintered by the method and allowed 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, N2, Ar, inert gas such as He, H _2, CO, various hydrocarbons, or their mixed atmosphere, further may be of various vacuum like.

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 , 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 the powder of Ti oxide or alkoxide is directly added, it is preferable to use a non-oxidizing atmosphere.

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

On the other hand, when TiC needs to be an oxide of Ti during firing, an oxygen atmosphere is preferable.

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 Al ₂ O ₃ —TiC sintered body thus obtained has a strength of 95 while maintaining a high level of Vickers hardness.
can be lowered from 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 Al 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.

V. Specific Actions and Effects of the Invention According to the present invention, it is preferable to further oxidize Ga, Ba, Ce, Nb with respect to a mixture containing 5 to 40% by weight of titanium carbide and 100 parts by weight of this mixture. And at least one kind of a carbonic acid compound and an oxide or alkoxide of Ti added in an oxide form so as to be contained in an amount of 0.01 to 10 parts by weight (in this case, Ga, B
0.01 to at least one of a, Ce, and Nb oxides.
5 parts by weight, or 0.01 to 5 parts by weight of Ti oxide may be contained, but it is desirable to contain both of them in an amount of 0.01 to 5 parts by weight. ), The center particle size of titanium carbide in the sintered body is 1.0 to 2.
It has a particle size of 5 μm and a particle size of 0.1 μm or less is regulated to 10% by weight or less, so that it has excellent workability, has a dense structure, has a large hardness, is nonmagnetic, and has high reliability. As a result, a ceramic material that does not fall off can be obtained. And
As a magnetic head slider material, the CS / S characteristics are also very good. Therefore, its use as a magnetic head slider material for high density recording is expected.

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 Al 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. 2% by weight of BaO was added to a mixture of 7) and 7) in a weight ratio of 7: 3, and wet mixing was performed for 20 hours by a ball mill.

The mixed slurry was dry-granulated and filled in a graphite 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, the sintered body was taken out of the mold and processed with a # 200 diamond grindstone to prepare a sample 100 having a diameter of 3 inches and a thickness of 4 mm.
Was produced.

The average particle size of TiC in the sintered body produced in this way was 1.5 μm, and the particle size distribution was observed by an electron micrograph. As a result, TiC having a particle size of 0.5 to 2.0 μm showed the total number of TiC particles. Was 92%.

Further, TiC having a particle size of 0.1 μm or less was 5%.

A sample 200 was prepared in the same manner as above except that the grain size of TiC used as a raw material when preparing the sintered body was 0.3 μm.

The average particle size of TiC in the sintered body produced in this manner is 0.
The particle size distribution was 8 μm, and the particle size distribution was observed by an electron micrograph. As a result, TiC having a particle size of 0.5 to 1.5 μm was 80% of the total number of TiC particles.

Further, TiC having a particle size of 0.1 μm or less was 15%.

The characteristics of the above samples 100 and 200 are shown below.

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 vibrating 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).

(4) CS / S characteristics (a) Abrasion resistance A thin film element of a sample is processed into a slider shape in which the thin film elements are collectively formed,
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.

It is represented by Rmax which is an index of surface roughness.

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

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

Example 2 Al ₂ O ₃ : T used in producing the sample 100 of Example 1
Samples were prepared in the same manner as Sample 100 except that various additives (Table 1) were added at the ratios shown in Table 1 to 100 parts by weight of the mixture of iC = 7: 3 (weight ratio). 10
1 to 109 (Table 1) were prepared.

In addition, Al ₂ used when the sample 200 of Example 1 was manufactured
Same as sample 200 except that various additives (Table 1) were added at a ratio shown in Table 1 to 100 parts by weight of a mixture of O ₃ : TiC = 7: 3 (weight ratio). To
Samples 201 to 203 (Table 1) were prepared.

The characteristics of these samples were evaluated in the same manner as in Example 1.

The results are shown in Table 1.

However, if chipping occurs, 5 or less are indicated as ○, 5
-10 is represented by Δ, and more is represented by X. Regarding dropout of particles, those with Rmax of 100Å or less are ◯, 10
Those that are 0 to 1000Å are indicated by Δ, and those that exceed 1000Å are indicated by x.

Regarding the particle size distribution, the range of the particle size occupying 92% was shown.

The effect of the present invention is clear from Table 1.

Then, by including the additive, the characteristics, particularly the dropout of grains are improved.

Example 3 The Al ₂ O ₃ powder and TiC powder used in Example 1 (particle size 0.
7 μm) in a weight ratio of 65:35, and 2% by weight of BaO was added, and the same treatment as in Example 1 was carried out to prepare Sample A of the present invention.

However, the firing atmosphere was an oxygen atmosphere.

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

Further, the average particle size of TiC in the sintered body was 1.5 μm, and the particle size distribution was observed by an electron micrograph. As a result, the proportion of particles having a particle size of 0.5 to 2.0 μm was 92%. , TiC having a particle size of 0.1 μm or less was 5%.

In the above, the same treatment was carried out except that TiC having a grain size of 0.3 μm (the one used in Example 1) used as a raw material when producing the sintered body was used, and a comparative sample B was produced. .

In this case, 11% by weight of TiC was changed to an oxide of Ti.

Further, the average particle size of TiC in the sintered body is 0.8 μm, the particle size distribution is such that the ratio of particles having a particle size of 0.5 to 1.5 μm is 80%, and the particle size of 0.1 μm or less. With T
iC was 15%.

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. A ceramic material containing 5 to 40% by weight of titanium carbide in a mixture containing titanium carbide and alumina, wherein the average particle diameter of titanium carbide in the sintered body is 1.0 to 2.5.
A ceramic material for a magnetic head slider, characterized in that the titanium carbide having a particle size of 0.1 μm or less is 10% by weight or less. 2. Based on 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina, Ga, Ba, Ce,
0.01 to at least one of Nb and Ti oxides.
A ceramic material containing 10 parts by weight, wherein the average particle size of titanium carbide in the sintered body is 1.0 to 2.5 μm, and 10% by weight of titanium carbide having a particle size of 0.1 μm or less.
The following are ceramic materials for magnetic head sliders.