JPH062618B2 - 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 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, Al ₂ O ₃ and TiC described in JP-A-56-140066, and yttrium oxide. (In some cases, it is contained as a constituent of a solid solution or a composite) or in the form of yttrium carbide (sometimes it is contained as a constituent of a double carbide or a composite), and hot isostatic pressing is performed. Obtained by a pressure (HIP) method, Al ₂ O ₃ , 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 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). ) 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, Al 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, Al 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, the sintering temperature when firing this is relatively high, and it is desired to lower the sintering temperature while maintaining these characteristics.

II Object of the Invention The object of the present invention is to lower the sintering temperature, to have particularly good CS / S characteristics, to have a dense structure, to prevent grains from falling out, to have a high hardness, and to be non-magnetic. Further, it is to provide a ceramic material which is excellent in workability in each step and which is 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 first aspect of the present invention is that, with respect to 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina, 0.01 to 500 parts by weight of Mn and Ti oxides, respectively.
It is a ceramic material for a magnetic head slider, characterized by containing 5 parts by weight.

In the second invention, 0.01 to 5 parts by weight of oxides of Mn and Ti, and Ga, Ba, Ce are added to 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina. And a ceramic material for a magnetic head slider, which contains 0.01 to 5 parts by weight of at least one compound selected from oxides of Nb and Nb.

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 made of alumina (Al
₂ O ₃ ) powder and titanium carbide (TiC) powder mixture containing Mn and Ti oxides, or at least one compound selected from Ga, Ba, Ce and Nb oxides. Is included.

In the above, by further containing an oxide such as Ga, the occurrence of chipping can be further reduced.

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

If the average particle size of TiC in the sintered body is less than 1.0 μm,
This is because the workability is extremely poor, and if the thickness 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, among TiC in the sintered body, those having a particle size of 0.1 μm or less are 10% by weight or less, and more preferably 10% by weight in total.
% Or less or 0 is preferable.

TiC with a particle size of 0.1 μm or less has high surface activity,
Reliability test and CS /
This is because it causes a defect in S characteristics.

In addition, such an alumina-titanium carbide sintered body is obtained by adding an Mn oxide (for example, MnO ₂ etc.) to a mixture of alumina (Al ₂ O ₃ ) powder and titanium carbide (TiC) powder.
Alternatively, a compound which becomes an oxide by firing, for example, a powder of a carbonate compound (for example, MnCO ₃ or the like) and an oxide of Ti are added and fired.

Further, oxides of Ga, Ba, Ce and Nb (for example, C
eO ₂ , GaO, Nb ₂ O _5, etc.) or a compound which becomes an oxide by firing, such as a carbonate compound thereof (eg (B
aCO ₃ etc.) may be added.

Examples of the method for adding the Ti oxide or the like include (1) Ti oxides (TiO ₂ , TiO, Ti ₂ O)
₃ or the like) or a powder of which at least the surface is Ti oxide, or a compound which becomes an oxide by firing, for example, an alkoxide of Ti ([(CH ₃ ) ₂ CHO] ₄ T.
i) and the like, 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.

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
It is considered that it plays a role of strengthening the grain bond between TiC and TiC.

The Al ₂ O ₃ powder is preferably finely divided, and the average particle diameter is preferably 0.1 to 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 for Al ₂ O _3.
˜95% by weight, and correspondingly the remaining 40-5% by weight is TiC.

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.

Mn is added to a mixture of _{Al 2 O 3 -TiC, Ga,} B
The average particle size of the powder of a, Ce, Nb oxides, carbonic acid compounds and the like is preferably 0.1 to 3 μm, and particularly preferably 0.5 to 1 μm.

When the Ti oxide or alkoxide is directly added to the Al ₂ O ₃ —TiC mixture as a powder, the average particle diameter of the Ti oxide or alkoxide powder is 0.1 to 3 μm.
m, particularly preferably 0.5 to 1.0 μm.

Further, the addition amount is 0.01 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, as an oxide with respect to 100 parts by weight of the Al ₂ O ₃ —TiC mixture.

If the addition amount of Mn oxide is less than 0.01 parts by weight,
This is because the effect of the present invention is lost and if the content exceeds 5 parts by weight, the uneven distribution of the additive in the sintered body increases.

If the addition amount of the oxide of Ti is less than 0.01 parts by weight,
If the present invention is no longer effective and exceeds 5 parts by weight, TiO ₂
This is because the uneven distribution in the sintered body is increased.

Further, when adding oxides of Ga, Ba, Ce and Nb, if the addition amount is less than 0.01 parts by weight, chipping cannot be reduced, and if it exceeds 5 parts by weight, the additive is burned. This is because the uneven distribution in the conjunctiva 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 Al ₂ O ₃ —TiC sintered body is usually a mixture of Al ₂ O ₃ powder and TiC powder such as Mn oxide or carbonate compound powder, and Ti oxide or alkoxide or surface-oxidized TiC. Powder, and also G
Powders of oxides, carbonates, etc. of a, Ba, Ce and Nb are added and mixed as required, and then formed into a compact, which is formed by hot press sintering in an oxygen atmosphere or a non-oxidizing atmosphere. It is obtained by sintering a body and allowing it to cool.

In this case, the sintering temperature is 1350 to 1700 ° C., which is 1 compared with the conventional one (for example, Japanese Patent Application No. 59-278810).
It is possible to lower the temperature by about 00 ° C.

And it is especially preferable to set it as 1500-1650 degreeC.

When the temperature is lower than 1350 ° C., a dense sintered body cannot be obtained, and when the temperature is higher than 1700 ° C.,
This is because 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 1000 ° 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 1250 to 1550 ° C. and the time is preferably 1 to 3 hours. The temperature in the HIP method is 115
The temperature can be set to 0 to 1400 ° C., and the temperature can be lowered by about 100 ° C. as compared with the conventional method (for example, Japanese Patent Application No. 59-278810) as in the hot press sintering method.

And it is preferable to set it as 1250-1300 degreeC especially.

This temperature range is set for the same reason as in the hot press sintering method.

Sintering time is 1 to 5 hours, pressure is 1000 to 1500 kg / c
m 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 300-40 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 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 becomes possible to increase the cutting resistance 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, 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina are mixed with an oxide of Mn, a carbonate compound, etc., and an oxide of Ti, alkoxide, etc. In the form of oxide, and if necessary, Ga, Ba, C
e, Nb oxides, carbonate compounds, etc.
Since it is added so as to be contained by 5 parts by weight, it is possible to lower the sintering temperature, has a dense structure, does not drop grains, has a high hardness, is non-magnetic, and has each step In, a ceramic material excellent in workability can be obtained.
As a magnetic head slider material, the CS / S characteristics are extremely 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 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. 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 graphite mold having an inner diameter of 77 mm. This was placed in a vacuum atmosphere for 1 hour at a sintering temperature of 13
Hot press sintering was performed at 50 to 1700 ° C. and a pressing pressure of 200 to 300 kg / 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.

Regarding the above samples 101 to 108 and 201 to 205,
The characteristics are shown in Table 1.

The method of evaluating the characteristics is as follows.

(1) Mirror Surface Machinability Each sample was lapped with green car band (GC) abrasive grains, and then polished with diamond abrasive grains, and the presence or absence of grain omission 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.

Those having an Rmax (index of surface roughness) of 100 or less are represented by O, those having a Rmax of 100 to 1000 are represented by Δ, and those exceeding 1000 are represented by X.

The average particle size of TiC in the sample of the present invention is 1.5 to 2.
0 μm and with a particle size of 0.1 μm or less is 10%
It was below.

From Table 1, 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 even when the sintering temperature is lower than that of the conventional sample. 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.

It was also found that the addition of Ga, Ba, Ce, and Nb oxides further improves the occurrence of chipping.

However, none of the comparative samples was satisfactory in terms of characteristics.

Example 2 To the mixture of the Al ₂ O ₃ powder and the TiC powder used in Example 1 at a weight ratio of 65:35, 1% by weight of MnCO ₃ was added, and the same treatment as in Example 1 was performed. Then, a sample A was prepared.

Further, CeO ₂ was further added in an amount of 0.2% by weight, and Sample B was similarly prepared.

However, the firing atmosphere was an oxygen atmosphere.

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.

The average particle size of these TiCs is 1.5 μm, 0.1
Those having a thickness of μm or less were 10% or less.

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

Claims (6)

[Claims] 1. A magnetic head slider characterized by containing 0.01 to 5 parts by weight of oxides of Mn and Ti with respect to 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina. Ceramic material. 2. An oxide of Mn and / or a compound which becomes these oxides by firing and / or an oxide of Ti is added to 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina. 0.01 for each
The ceramic material for a magnetic head slider according to claim 1, wherein the ceramic material is added so as to be contained in an amount of up to 5 parts by weight and sintered. 3. The average particle size of titanium carbide in the sintered body is 1.0.
The ceramic material for a magnetic head slider according to claim 1 or 2, wherein the ceramic material has a thickness of ˜2.5 μm. 4. An oxide of Mn and Ti is added in an amount of 0.01 to 5 parts by weight, and Ga and B are added to 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina.
at least 1 selected from oxides of a, Ce and Nb
A ceramic material for a magnetic head slider, which comprises 0.01 to 5 parts by weight of the above compound. 5. An oxide of Mn and / or a compound which becomes an oxide of these by firing, relative to 100 parts by weight of a mixture containing 5 to 40% by weight of titanium carbide and alumina.
The oxides of a, Ba, Ce, and Nb and / or the compounds that become these oxides by firing, and the oxides of Ti are added so that each of them is contained in an amount of 0.01 to 5 parts by weight, and the mixture is fired. The ceramic material for a magnetic head slider according to claim 4, which is attached. 6. The average particle size of titanium carbide in the sintered body is 1.0.
The ceramic material for a magnetic head slider according to claim 4 or 5, wherein the ceramic material has a thickness of ˜2.5 μm.