JPH0782617B2 - Non-magnetic substrate for magnetic head and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a non-magnetic substrate for a non-magnetic magnetic head for depositing a metallic magnetic film, and a method for manufacturing the same.
In particular, the present invention relates to a non-magnetic substrate for a magnetic head having excellent chipping characteristics by machining and a method for manufacturing the same.

PRIOR ART Conventionally, for this type of application, the present inventors have proposed CoO-N
Research on iO-based ceramics has been advanced from the past, and CoxNi
_It has already been disclosed that an oxide having a composition of _2- xO ₂ (where 0 ≦ x ≦ 1.8) is effective.

Furthermore, studying the MgO-CaO-CoO-NiO ceramics, MgO, respectively CaO is 30 mol% or less, the balance being CoxNi _2- xO ₂ (provided that 0 ≦ x ≦ 1.8) comprising an oxide composition effective also It was disclosed as being.

In addition, as a result of investigating additive materials related to these oxides, MnO, TiO ₂ , Al ₂ O ₃ , CaO, Y ₂ O ₃ , TiN, B ₂ O ₃ , SiO ₂
Have been found to be effective and also disclosed.

As a method for producing these oxides, mixing, calcination,
It has been disclosed that it is effective to carry out pulverization, granulation, CIP, atmospheric sintering, and HIP sequentially.

However, these oxides have different chipping characteristics depending on the production conditions, and depending on the conditions, there is a drawback that large chipping occurs during machining.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention solves the above-mentioned drawbacks, and specifically has a crystal grain size of 5 μm or less and a thermal expansion coefficient of 130 × 10 ⁻⁷ / ° C. or more, and Vickers It is an object to provide a material having a hardness of 500 to 700 and not causing an excessive chemical erosion reaction between other head constituent materials.

It is also an object to provide a method of manufacturing the above materials.

Configuration of the Invention Namely, the present invention _{is, (1) CoxNi 2- xO 2} ( provided that 0 <x ≦ 1.
The non-magnetic substrate for a magnetic head according to 8), wherein the crystal grain size is 5 μm or less.

The present invention also includes (2) mixing, calcination, fine pulverization,
In the atmosphere sintering of the method for manufacturing a non-magnetic substrate for a magnetic head, which comprises sequentially performing granulation, CIP, atmosphere sintering, and HIP, the hot press treatment is performed at 1150 to 1300 ° C. in an oxygen atmosphere. The present invention relates to the method (1) for manufacturing a non-magnetic substrate for a magnetic head.

Furthermore, the present invention provides (3) mixing, calcination, fine pulverization,
In the atmosphere sintering of the method for manufacturing a non-magnetic substrate for a magnetic head, which comprises sequentially performing granulation, CIP, and atmosphere sintering, hot pressing is performed at 1150 to 1300 ° C. in an oxygen atmosphere, as described above ( 1) A method for manufacturing a non-magnetic substrate for a magnetic head.

Means and Actions for Solving Problems The present inventors have been researching CoM-NiO ceramics from the past, but as a result of detailed study of the relationship between the chipping characteristics and the grain size during machining, It has been found that when the crystal grain size is 5 μm or less, chipping during machining is small and the number is small, which is effective.

In CoO-NiO ceramics, the chipping characteristics (chipping amount, size of chipping) during machining are closely related to the crystal grain size. That is, the inventors have found that the smaller the crystal grain size, the better the chipping characteristics.

Specifically, it has been understood that the size (G) of the crystal grain size and the size (T) of the maximum chipping have a relationship of the following equation when the abrasive grain size is 2 to 6 μm.

T ≦ 2G to 3G Considering that the allowable range of the maximum chipping size during machining is about 10 μm, it is necessary to suppress the crystal grain size to 5 μm or less from the above equation.

Further, it has been found that it is effective to use a hot press as a manufacturing method for achieving the above object.

When using a hot press, the temperature conditions for pressureless sintering (1230
It is possible to densely sinter at a temperature lower than (~ 1400 ℃), and therefore there is an advantage of suppressing the growth of crystal grains of the sintered body.

Hot pressing is preferably performed in an oxygen atmosphere because of the behavior of oxides. Specifically, it is desirable to switch the inert gas (low temperature side) and oxygen (high temperature side) at 800 to 1000 ° C. The optimum treatment temperature varies depending on the molar ratio of CoO and NiO, but is preferably 1150 to 1300 ° C.

The manufacturing method will be specifically described below.

Each commercially available oxide is used as a raw material, weighed to have a desired composition, and mixed by a ball mill. Mixing is carried out, for example, in a wet ball mill in ethanol for 10 to 30 hours.

After drying, CIP molding, calcination in Ar at 850-1100 ℃,
Then, it is crushed using a coarse crusher and sieved with a sieve of 100 to 200 μm.

The calcined powder can be further processed, for example, in a wet type ball mill in ethanol.
Treat for ~ 72 hours and pulverize to 1 μm or less.

After granulating this, it is CIP molded and hot pressed in O ₂ .

The conditions are 1100 to 1300 ° C, corresponding to the CoO / NiO molar ratio, and 1
00 to 500 kg / cm ² , 1 to 2 hours is desirable.

This sintered body is further HIP processed. This is preferable for improving strength. The condition is 800-1200kg / c
m ^2, 1000~1250 ℃, desirably 1 to 2 hours. The HIP treatment temperature is preferably lower than the hot press treatment temperature. This makes it possible to suppress the growth of the crystal grain size during the HIP treatment.

It was confirmed that the sintered body thus obtained was dense, had a small crystal grain size, had good chipping characteristics, and was superior to conventional materials.

The oxide Ni represented by Example composition formula _{CoxNi 2- xO 2 (x = 1.0} )
Adjusted from O and CoO. 1.5 wt% of Al ₂ O ₃ and 2.0 of CaO
wt%, added as an additive. Mixing was done in a wet ball mill in ethanol for 22 hours.

After drying, it was CIP molded, calcined in Ar at 1000 ° C., and then pulverized to 150 μm or less.

The calcined powder was further treated with a wet ball mill in ethanol for 70 hours and finely pulverized to 1 μm or less. This was granulated, then CIP molded and sintered by hot pressing in O ₂ at 1250 ° C.

The characteristics of this sintered body are shown below.

Relative density 98.5% Crystal grain size Maximum 5 μm Hardness Hv 625 Transverse strength 27 kg / mm ² Thermal expansion coefficient 132x10 ^-7 / ℃ This sintered body was cut and polished to prepare a 26x26x0.7 (mm) substrate. This is a diamond abrasive grain (# 3000, C / C = 1
00) was used for cutting with a blade. The cutting conditions were a rotation speed of 20,000 rpm, a cutting depth of 0.2 mm, and a feed of 0.5 mm / sec.

The maximum value of chipping at this time is shown in Table 1. Further, the number of chippings on one side (26 mm) of the substrate was measured for each size and shown in Table 2. As a comparative example, the chipping characteristics of sintered bodies having different maximum crystal grain sizes which are sintered by atmospheric pressure sintering are shown.

EFFECTS OF THE INVENTION (1) The substrate according to the present invention has excellent chipping characteristics by machining.

(2) The crystal grain size of the non-magnetic substrate for a magnetic head manufactured by this manufacturing method can be suppressed to 5 μm or less.

This has the advantage that chipping can be suppressed during cutting.

(3) Further, by increasing the strength, it is possible to shorten the life of the magnetic head and suppress the deformation and cracking of the non-magnetic substrate, and there is an advantage that the head has excellent wear resistance and durability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-2-94408 (JP, A) JP-A-2-94407 (JP, A) JP-A 1-287811 (JP, A) JP-A-2- 168602 (JP, A)

Claims (3)

[Claims] 1. A CoxNi _2- xO ₂ (provided that 0 <x ≦ 1.8) in ceramics, non-magnetic substrate for a magnetic head, characterized in that the crystal grain diameter of 5μm or less. 2. Mixing, calcination, fine pulverization, granulation, CI
In the atmosphere sintering of the method for manufacturing a non-magnetic substrate for a magnetic head, which comprises sequentially performing P, atmosphere sintering, and HIP, in an oxygen atmosphere, hot pressing is performed at 1150 to 1300 ° C. A method of manufacturing a non-magnetic substrate for a magnetic head according to item (1). 3. Mixing, calcination, fine pulverization, granulation, CI
P, hot-pressing treatment at 1150 to 1300 ° C. in an oxygen atmosphere in the atmosphere sintering of the method for manufacturing a non-magnetic substrate for a magnetic head, which comprises sequentially performing atmosphere sintering. A method of manufacturing a non-magnetic substrate for a magnetic head according to the item (1).