JPH0818861B2 - Ceramic material and magnetic head manufacturing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Technical Field The present invention relates to a method of manufacturing a ceramic material and a magnetic head.

2. Description of the Related Art Conventional technology and its problems Conventionally, as a ceramic material, particularly as a slider material for a magnetic head, for example, a ceramic material such as calcium titanate, barium titanate, potassium titanate, strontium titanate, alumina, or crystallized glass is generally used. ing.

However, when the above ceramic is used as a slider material of a magnetic head having a sendust-based core, the following inconvenience occurs.

That is, the coefficient of thermal expansion of the sendust-based core material is 13
To 0 × 10 ^-7 in the range of about deg ^-1, said ceramic material is ^{10 × 10 -7 ~70 × 10 -7} deg about ^-1, the difference between them is about 2 to 13. times.

For this reason, when the sendust-based core material and the above ceramic material are provided via a thermosetting or reactive adhesive or an inorganic adhesive, by heating during adhesive curing and fusion, When sendust is provided as a thin film on the ceramic substrate by sputtering or the like, thermal spalling of the ceramic is likely to occur in any of these cases due to the temperature rise of the substrate.

Further, such a ceramic material as a magnetic head slider material has poor secondary workability and is apt to cause chipping or the like.

 In addition, workability during grinding and polishing is also poor.

Therefore, there is a demand for a ceramic material that eliminates such inconvenience and has good productivity.

II. Objects of the Invention An object of the present invention is to prevent thermal spalling of the slider that occurs during the manufacture of a magnetic head and to provide a ceramic material excellent in secondary workability, and a method of manufacturing a sendust-based magnetic head using this material. To provide.

III. Disclosure of the Invention Such an object is achieved by the present invention described below.

That is, the first invention is a ceramic material in which calcium titanate powder and titanium carbide powder are mixed and sintered so that titanium carbide is 5 to 20 wt% with respect to the total of calcium titanate and titanium carbide. Is a manufacturing method.

The second invention has a slider and a core, and when the slider manufactures a magnetic head containing calcium titanate and titanium carbide, the content of titanium carbide is relative to the sum of calcium titanate and titanium carbide. This is a method of manufacturing a magnetic head in which calcium titanate powder and titanium carbide powder are mixed so as to be 5 to 20 wt% and sintered to obtain a slider, and further a core is formed.

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

A calcium titanate-titanium carbide sintered body is used as the ceramic material of the present invention, particularly the magnetic head slider material. That is, a mixture of calcium titanate (CaTiO ₃ ) powder and titanium carbide (TiC) powder is manufactured by an ordinary sintered body manufacturing method.

The CaTiO ₃ powder used is preferably finely divided and has an average particle diameter of 0.1 to 3.0 μm, particularly 0.5 to 1.0 μm.

Although CaO and TiO ₂ can be used as raw materials,
If the pre-calcined CaTiO ₃ powder is not used, the shrinkage rate during sintering will be large, and during sintering, CaO needle-shaped powder will easily grow into grains, and grains will fall off during mirror finishing, and good mirror finishing is achieved. Accuracy, that is, good smoothness cannot be obtained. Also CaO
The powder has high water absorption and is difficult to use.

Also, it is preferable that the TiC powder is also pulverized similarly to CaTiO _3, and the average particle size is 0.1 to 3.0 μm, particularly 0.5 to 1.5 μm.
It is preferred that

Mixing ratio of CaTiO ₃ and TiC is, TiC is 5 to 20 wt% with respect to the total sum of the CaTiO ₃ and TiC.

When TiC is less than 5 wt%, it becomes difficult to control the grain growth of CaTiO ₃ , and chipping or grain shedding during cutting or mirror finishing occurs. On the other hand, if it exceeds 20 wt%, the coefficient of thermal expansion decreases, and the cutting speed decreases. Then, heat spalling is likely to occur, and the mirror surface workability also deteriorates.

Further, usually, the sintered body of the present invention is composed only of CaTiO ₃ and TiC, but as other additives, BaCO ₃ , CeO ₂ , T
0.1 to 10 wt% of iO ₂ , NiO ₂ and CaO may be added to the whole.

Note that CaTiO ₃ and TiC are usually near their stoichiometric composition.

A CaTiO ₃ -TiC sintered body is usually formed by mixing a predetermined amount of these powders into a molded body, sintering the molded body by a hot press sintering method in a non-oxidizing atmosphere, and allowing it to cool. can get.

The sintering temperature in this case is 600-1500 ℃, especially 800-1200 ℃
Is preferred.

If the temperature is lower than 600 ° C, a dense sintered body cannot be obtained.
This is because if the temperature is higher than 500 ° C, the sublimation of CaTiO ₃ 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, a mixed atmosphere thereof, or a vacuum.

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

 The sintering time is generally 1 to 3 hours.

In addition, at the time of sintering, the raw powder compact is pre-sintered in a non-oxidizing atmosphere (for example, it is preferable to vacuum up to 400 ° C. and then Ar atmosphere), and then this pre-sintering in a HIP furnace. The hot isostatic pressing (HIP) method of sintering the body may be used. The presintering temperature is preferably 600 to 1500 ° C. and the time is preferably 1 to 3 hours. In the HIP method, the temperature is 400 to 1350 ° C, the sintering time is 1 to 5 hours, and the pressure is 100.
It is 0 to 1500 Kg / cm ² , and it is desirable to carry out in an inert atmosphere such as Ar.

In this case, Ar gas or the like is pressurized to 300 to 400 Kg / cm ² at room temperature, and then pressure is applied by heating as described above.

Incidentally, in the sintered body thus formed, part of TiC may be changed to TiO ₂ .

The CaTiO ₃ -TiC sintered body thus obtained has a thermal expansion coefficient of 100 × 10 ^{−7 to} 130 × 10 ⁻⁷ deg ⁻¹ as its physical property value, and the amount of TiC added is changed. Therefore, this value can be arbitrarily set to some extent.

And since this value is a coefficient of thermal expansion of about the same value as the sendust-based core material, the CaTiO ₃ -TiC of the present invention.
If the sintered body is used as the slider material of the sendust magnetic head, the generation of thermal spalling, which has conventionally occurred as described above, can be almost completely prevented.

Further, the ceramic material of the present invention has high hardness, excellent wear resistance, and excellent secondary workability, so that chipping and grain detachment are extremely unlikely to occur even when the working speed is increased. The smoothness after mirror finishing is also good. As described above, the ceramic material of the present invention can be used for various purposes, but when it is used as a magnetic head slider, particularly in a sendust-based magnetic head, it exhibits a particularly excellent effect.

A sendust type magnetic head using such a magnetic head slider has a head core made of various known sendust materials, a winding, and the like.

The sendust forming the head core may have various known compositions.

The thermal expansion coefficient of the sendust core is usually 90 × 10
It is about ^{-7 to} 130 × 10 ^-7 deg ^-1 .

When a head core made of such sendust and a slider made of the composition material of the present invention are layered via a thermosetting or reactive adhesive or glass, or the slider is used as a substrate and sendust is formed into a thin film by sputtering or the like. In any case, the thermal expansion coefficient of these sliders is almost the same, and thermal spalling of the slider hardly occurs.

V. Specific Action and Effect of the Invention According to the present invention, it has high hardness and excellent workability,
Moreover, a ceramic material having a thermal expansion coefficient similar to that of the sendust material can be obtained.

Therefore, when the ceramic material of the present invention is used as a slider of a sendust-based magnetic head, it is possible to prevent the thermal spalling of the slider which has occurred during the conventional manufacturing process, and this slider material is subjected to secondary processing. It also has excellent properties.

VI. Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown to explain the effect of the present invention in more detail. Examples CaTiO ₃ (purity 99.9%) powder having an average particle size of 0.5 μm and average particles TiC having a diameter of 0.5 μm (purity 99%, carbon content 19% or more and 1% or less thereof is free coquence) was added at a ratio shown in Table 1, and wet mixing was performed for 40 hours by a ball mill. .

The mixed slurry was passed through # 35 sieve, dried and granulated, and then filled in a graphite mold having an inner diameter of 77 mm.

This for 1 hour in a vacuum atmosphere, sintering temperature 600 ~ 1500
Hot press sintering was carried out at a temperature of ℃ and a pressing pressure of 200 to 300 Kg / cm ² .

After cooling, remove each sintered body from the mold and # 200
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 TiC was also prepared in the same manner as above. Further, a sample 401 using both TiO ₂ powder and CaO powder having an average particle size of 0.5 μm was prepared.

Table 1 shows the characteristics of the above samples 101 to 105, 201 to 202 and 301 and 401.

 The evaluation of the characteristics is as follows.

(1) Heat spalling After the sample in which sendust was thinned on the substrate by sputtering or the like was cut and processed, the adhesion between the sendust and the substrate when the cut surface was ground and polished was observed under a microscope.

(2) Cutting workability (a) Cutting performance (constant pressure cutting experiment) Glass was bonded onto a uniaxial thrust bearing, and a sample (width 30 mm, thickness 4 mm) was bonded onto it, and this sample was applied to 500
The cutting speed at the time of pulling with a weight of 1000 g and 1000 g 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 cutting surface (width 30 mm, thickness 4 mm) About the sample of 30m
Incidence rate per m) was examined with a microscope (200 times).

Five or less are indicated by O, 5-10 by Δ, and more are indicated by X.

(3) Coefficient of thermal expansion The coefficient of thermal expansion at 40 ℃ ~ 300 ℃
X 3 x 20 ^L ) and measured.

The sample was processed into 3 × 3 × 20 ^L.

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

In addition, the smoothness at this time is measured, and if Rmax is less than 30 nm, ◎, 30
-80 nm was marked with ◯, and more than 80 nm was marked with x.

From the results in Table 1, the effect of the present invention is clear.

That is, if the TiC content is less than 5 wt%, chipping frequently occurs and grain dropout frequently occurs. On the other hand, if the content of TiC exceeds 20 wt%, the coefficient of thermal expansion decreases, resulting in an increase in thermal spalling, a decrease in cutting processing speed and mirror surface workability, and an increase in grain loss and surface roughness. Further, when the CaTiO ₃ calcined powder is not used, the mirror surface workability is deteriorated and the grains are dropped and the surface roughness is increased.

Claims (3)

[Claims] 1. A method for producing a ceramic material, which comprises mixing calcium titanate powder and titanium carbide powder and sintering the mixture so that titanium carbide is contained in an amount of 5 to 20 wt% with respect to the sum of calcium titanate and titanium carbide. Method. 2. When manufacturing a magnetic head having a slider and a core, wherein the slider contains calcium titanate and titanium carbide, the content of titanium carbide is 5 to the total amount of calcium titanate and titanium carbide. A method of manufacturing a magnetic head, wherein calcium titanate powder and titanium carbide powder are mixed so as to be 20 wt% and sintered to obtain a slider, and further a core is formed. 3. The method of manufacturing a magnetic head according to claim 2, wherein the core is a sendust material.