JPH1079309A - Hematite material for magnetic head and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a magnetic head hematite material which is high in density and excellent in reduction resistance at a high temperature under a low oxygen partial pressure. SOLUTION: Material composed of hematite and 5mol% or below of one element selected out of SnO2 , TiO2 , and ZrO2 is mixed well, molded, and subjected to an HIP treatment, and thus a sintered compact is obtained. Tetravalent cation of SnO2 , TiO2 , or ZrO2 is substituted for Fe<3+> of hematite, whereby oxygen ion hole is restrained from being generated, and hematite is restrained from being reduced into magnetite. By this setup, a magnetic head slider which is excellent in frictional wear resistance to a hard disc and high in density can be manufactured. A magnetic head excellent in magnetic characteristics can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hematite material for a magnetic head, and more particularly to a hematite material for a magnetic head suitable for a magnetic disk device having good friction and wear characteristics with respect to a hard disk, and a method for producing the same. .

[0002]

2. Description of the Related Art Magnetic heads for magnetic disk drives (HDDs) are classified into three types: monolithic heads, composite heads, and thin film heads. The monolithic head has a structure in which the slider and the head are integrated, and the composite head has a structure in which a magnetic core is adhered to a slit portion of the slider with mold glass or the like. On the other hand, the thin film head has a magnetic core and a coil formed on the end face of the slider. Of these magnetic heads, the composite head and the thin film head can cope with high recording density.

Conventionally, these slider materials include non-magnetic ceramics such as calcium titanate and barium titanate in a composite head, and A in a thin film head.
l ₂ O ₃ -TiC nonmagnetic ceramic composition (AlTiC) is used. When the hard disk is rotating at high speed, the slider floats and does not come into contact with the hard disk, but it comes into contact when the hard disk starts rotating and stops. Is important.

[0004]

However, non-magnetic ceramics such as calcium titanate, barium titanate, and Al ₂ O ₃ —TiC, which have been conventionally used, have friction and wear characteristics due to repeated start and stop of the hard disk. However, there is a problem such that the metal is deteriorated.

Hematite (α-Fe ₂ O ₃ , hereinafter simply referred to as “Fe ₂ O ₃ ”) has been known as a material having an excellent frictional wear characteristic with respect to a hard disk.
Since the slider material for the magnetic head is required to be a dense material without defects, HIP is required in the manufacturing process.
(Hot Isostatic Pressing) processing is required. However, since this HIP treatment is performed at a high temperature of 1000 ° C. or more in a low oxygen partial pressure atmosphere, hematite is reduced to generate magnetite (Fe ₃ O ₄ ). Since magnetite is a ferromagnetic material, a hematite-based sintered body containing magnetite is not preferable as a slider material for a magnetic head.

In the process of manufacturing a magnetic head, when a Fe—Al—Si magnetic film formed on a hematite substrate is subjected to a heat treatment, hematite is exposed to a high temperature and a high vacuum. There is a problem of easy generation.

In the field of magnetic recording, a magnetic recording medium having a high coercive force and a residual magnetic flux density has been used in accordance with an increase in the density of a recording signal. Therefore, a core of a magnetic head for performing magnetic recording or reproduction is used. As a material, a magnetic film having high saturation magnetization and high magnetic permeability is required. As such a magnetic film having high saturation magnetization and high magnetic permeability, Fe-M-
C-based nanocrystalline alloy (M: IVB group, VB group, IIIA
Group, IVA group) or Fe-based alloy (M: IVB group, VB group,
(IIIA, IVA) magnetic films are known. These alloy magnetic films are formed on a substrate by sputtering or the like.

[0008] depositing the alloy magnetic film for high-density recording as described above in Fe ₂ O ₃ substrate, there is a problem that the magnetic film is easily peeled off, Fe ₂ O ₃ in order to avoid this
_2. Description of the Related Art An Al ₂ O ₃ layer is formed as a buffer layer on a substrate. However, after forming the alloy magnetic film, for the purpose of obtaining a soft, sometimes heat treated at or under vacuum inert gas atmosphere is performed by the heat treatment, the Fe ₂ O ₃ substrate and the buffer layer A ferromagnetic magnetite layer in which Fe ₂ O ₃ is reduced is generated at the interface. Since the magnetite layer causes magnetic interaction with the alloy magnetic film, there is a problem that high magnetic permeability cannot be obtained from the alloy magnetic film.

Japanese Patent Publication No. 1-2220 (Japanese Patent Application Laid-Open No.
46751 No.) publication, as the slider member for head to magnetic, good reactivity with the glass during glass bonding and generation of bubbles is small, yet in order to prevent discoloration of the slider member, Al ₂ O _3, ZrO ₂ , ceramics in which TiO ₂ , CeO _{2 and the} like are added to Fe ₂ O ₃ , which is a main component, are disclosed. However, this publication does not disclose any reduction resistance of Fe ₂ O ₃ , and the amount of oxide added is extremely wide as 40% by weight or less.

An object of the present invention is to provide a hematite-based material for a magnetic head which is excellent in reduction resistance even under heating conditions after HIP treatment and sintering, and a magnetic head made of such a material.

[0011]

According to a first aspect of the present invention, in a hematite material for a magnetic head containing Fe ₂ O ₃ as a main component, SnO ₂ , TiO ₂ and ZrO ₂ are added to Fe ₂ O _3. Is provided in an amount of 5 mol% or less, thereby providing a hematite-based material for a magnetic head.

In the present invention, the material of the hematite substrate is Sn
By adding at least one compound selected from O ₂ , TiO _2, and ZrO ₂ , the tetravalent cation of the compound is substituted and solid-solved, thereby suppressing the reducing property of the hematite substrate. Hereinafter, the principle will be described.
In the generation reaction of magnetite by reduction of hematite, diffusion of oxygen ions in hematite is the rate-determining step. Since the diffusion rate of oxygen ions depends on the concentration of oxygen ion vacancies, it is considered that the generation of magnetite can be suppressed by reducing the concentration of oxygen ion vacancies. When the Fe ³⁺ site of hematite is replaced with a cation having a valence of 4 or more, Fe ²⁺ is generated under an electrically neutral condition.

[0013]

[Formula 1] _{^{M 4+ → M 'Fe + Fe}} ' Fe ··· (1) ( in the formula, M _'Fe indicates the M ^4+, which was replaced with Fe ³⁺ site (charge +1), _Fe' Fe Is Fe ^{2+ at the} Fe ³⁺ site
(Charge is -1)

On the other hand, the equilibrium reaction between oxygen ion vacancies in hematite and the oxygen partial pressure of the atmosphere is expressed as follows.

## STR2 ## ^{_{O 0 * → V 0 "+}} 2Fe 'Fe + 1/2 O 2 ··· (2) ( in the formula, O ₀ ^* indicates the O ^2- of O ^2- site (charge 0) , V ₀ ″ represent O ²⁻ vacancies (charge is +2)

This equilibrium reaction equation shows that the oxygen ion vacancy concentration decreases as the Fe ²⁺ concentration increases. That is, as shown in the above (1), by substituting a cation having four or more valences, Fe ²⁺
By increasing the concentration, the generation of oxygen ion vacancies can be suppressed, and the diffusion rate of oxygen ions, which is the rate-determining reaction of magnetite generation, can be reduced.

According to the present invention, TiO ₂ , SnO _2, and ZrO ₂ have been found to be suitable as a cation additive having four or more valences satisfying the formula (1). It is necessary to adjust the addition amount of the cation to 5 mol% or less. If the amount of the cation exceeds 5 mol%, a dense sintered body cannot be obtained because oxygen gas released by the solid solution reaction during firing is left as pores in the sintered body. In order to make the effect of the resistance to reduction by the cation addition effective, the lower limit of the addition amount is preferably 1 mol%.

According to a _second aspect of the present invention, Fe ₂ O ₃
The method of manufacturing a hematite-based material for head to magnetism as a main component, SnO ₂ to Fe ₂ O _3, TiO ₂ and Zr
A method for producing a hematite-based material for a magnetic head, characterized by sintering a raw material powder containing at least one kind of O ₂ at 5 mol% or less.

As a method for producing the hematite-based material for a magnetic head according to the present invention, a general powder metallurgy technique can be used. A cation having a valence of 4 or more, for example, at least one oxide selected from SnO ₂ , TiO ₂ , and ZrO ₂ is added to the hematite powder in an amount of 5 mol% or less;
After performing the mixing, calcining, pulverizing, and forming steps, baking is performed, and further a HIP treatment is performed, whereby a dense sintered body can be obtained. In the present invention, the reduction resistance of hematite is improved by the addition of the cation.
It can be carried out at a high temperature of １1200 ° C. and an oxygen partial pressure of 10 ^-4 to 10 ^-5 atm. The forming step may include a granulating step, a mold forming step, and a CIP (Cold Isostatic Pressing) forming step. The sintered body obtained as described above is
It is a material suitable for a slider material for a magnetic head, which is dense, has excellent reduction resistance under high temperature and low oxygen partial pressure, and has excellent friction and wear characteristics with respect to a hard disk.

According to a third aspect of the present invention, the magnetic head is manufactured using a hematite-based material for a magnetic head containing at least 5 mol% of SnO ₂ , TiO ₂ and ZrO ₂ in Fe ₂ O ₃ as a main component. A magnetic head is provided. Using the hematite-based material for a magnetic head according to the first aspect of the present invention, a magnetic head can be manufactured as follows. After the hematite-based material for a magnetic head according to the present invention is processed into a substrate, for example, a slider shape, a buffer layer is formed with an oxide such as Al ₂ O ₃ or CoO by sputtering or the like. Then, Fe-MC-based nanocrystalline alloys (M: IVB, VB, IIIA, IVA) and Fe-M-based alloys (M: IVB, VB, IIIA,
An alloy magnetic film of group IVA) is formed on the buffer layer by sputtering or the like. Fe-MC-based nanocrystalline alloys include, for example, Fe-Si-Al-Hf-Ta-C, Fe-Si
-Al-Hf-C, Fe-Hf-C, etc. can be used, and Fe-Si-Al, Fe-
A Si alloy can be used. The thickness of the alloy magnetic film is
In consideration of the track width, magnetic recording, and reproduction performance of a magnetic head, 1 μm to 20 μm is preferable. As the sputtering gas, an inert gas such as Ar can be used. After forming the alloy magnetic film by sputtering, it may be subjected to a heat treatment for the purpose of obtaining soft magnetism before the magnetic head is manufactured.

[0020]

EXAMPLES Hereinafter, the hematite material for a magnetic head according to the present invention will be specifically described with reference to examples. [Example 1] SnO ₂ was added to a hematite powder at a molar ratio of 1 mo.
1%, mixed in a wet ball mill using ethanol as a medium, calcined at 800 ° C., and pulverized in a ball mill. The obtained powder was preliminarily molded by uniaxial pressure molding and then CIP molded at 150 MPa. After sintering the molded body at 1150 ° C. in the atmosphere under normal pressure for 10 hours, 1100 ° C.
HIP processing was performed at 100 MPa for 1 hour.

A sintered body was manufactured under the same conditions as above, except that the amount of SnO ₂ was changed to a molar ratio of 3 and 5 mol%, respectively.

The relative density of the obtained sintered body was 99% or more in any of the cases where the added amount of SnO ₂ was 1 mol%, 3 mol% and 5 mol%. A part of each of the obtained sintered bodies was cut out as a thermogravimetric change measurement sample, and thermogravimetric changes were measured in a nitrogen atmosphere having an oxygen partial pressure of 2 × 10 ⁻⁴ atm or less. Table 1 shows the results.

[0023]

[Table 1]

A decrease in the weight of the sample indicates that reduction from hematite to magnetite has occurred. From Table 1, the starting temperature of weight loss due to the magnetite generation reaction is S
From the fact that the temperature shifts to the high temperature side with the increase in the added amount of nO _2, it can be seen that the reduction of hematite is suppressed as the added amount of SnO ₂ increases in the range of 1 to 5 mol%.

Comparative Example 1 SnO ₂ was added to hematite powder in an amount of 7
A sintered body was produced under the same conditions as in Example 1 except that the molar ratio of mol% was added. The relative density and the thermogravimetric change were measured in the same manner as in Example 1. The relative density after normal pressure sintering is 96.2%, and the relative density after HIP treatment is also 98.4%.
%, It is not suitable as a slider material for a magnetic head.

Example 2 TiO ₂ was added to hematite powder,
1, 3 and 5 mol% were added at a molar ratio, respectively, and mixed by a wet ball mill using ethanol as a medium.
After calcination, ball mill pulverization was performed. After each of the obtained powders is pre-formed by uniaxial pressing, 150
CIP molding was performed at MPa. These compacts are placed in the atmosphere 11
After normal pressure sintering at 50 ° C for 10 hours, 1100 ° C, 100
HIP processing was performed for 1 hour under the conditions of MPa.

The relative density of each of the obtained sintered bodies was 9
9% or more. A part of each sintered body was used as a thermogravimetric change measurement sample, and the thermogravimetric change was measured in a nitrogen atmosphere having an oxygen partial pressure of 2 × 10 ⁻⁴ atm or less. Table 1 shows the results. From Table 1, it can be seen that the starting temperature of the weight loss due to the magnetite generation reaction has shifted to a higher temperature with an increase in the amount of TiO ₂ added, and thus the reduction of hematite is suppressed.

Comparative Example 2 TiO ₂ was added to hematite powder
A sintered body was produced under the same conditions as in Example 2 except that the molar ratio of mol% was added. The relative density and the thermogravimetric change were measured in the same manner as in Example 2. The relative density after normal-pressure sintering is 96.5%, and the relative density after HIP processing is also 98.6%.
%, It is not suitable as a slider material for a magnetic head.

Example 3 ZrO ₂ was added to hematite powder,
1, 3 and 5 mol% were added at a molar ratio, respectively, mixed by a wet ball mill using ethanol as a medium, calcined at 800 ° C., and then ball milled. After pre-molding each of the obtained powders by uniaxial pressing, 150M
CIP molding was performed at Pa. This molded body is heated at 1150 ° C.
Sintering for 10 hours at 1100 ° C, 100MPa
For one hour.

The relative density of each of the obtained sintered bodies was 99
% Or more. A part of each sintered body was used as a thermogravimetric change measurement sample, and thermogravimetric changes were measured in a nitrogen atmosphere at an oxygen partial pressure of 2 × 10 ⁻⁴ atm or less. Table 1 shows the results.
From Table 1, it can be seen that the reduction temperature of hematite is suppressed because the onset temperature of the weight loss due to the magnetite generation reaction shifts to a higher temperature with an increase in the amount of ZrO ₂ added.

Comparative Example 3 A sintered body was manufactured under the same conditions as in Example 3 except that ZrO ₂ was added to the hematite powder at a molar ratio of 7 mol%. The relative density and the thermogravimetric change were measured in the same manner as in Example 2. The relative density after normal pressure sintering is 9
6.9%, and the relative density after HIP processing is also 98.2%.
Therefore, it is not suitable as a slider material for a magnetic head.

Comparative Example 4 A sintered body of hematite alone was produced under the same conditions as in Example 1 except that SnO ₂ was not added. Although the relative density of the obtained sintered body was 99% or more, generation of a magnetite layer was observed on the surface of the sintered body after the HIP treatment. Further, as shown in Table 1, the temperature at which the weight loss started by the thermogravimetric change measurement was lower than those in Examples 1 to 3. Therefore, it is not suitable as a slider material for a magnetic head.

Comparative Example 5 A sintered body was produced under the same conditions as in Example 1 except that Al ₂ O ₃ was added to the hematite powder at a molar ratio of 1, 3 and 5 mol%, respectively. Table 1 shows the results of the relative density and thermogravimetric measurement of the obtained sintered body. The relative density of each of the obtained sintered bodies was 99% or more.
Formation of a magnetite layer was observed on the surface of the sintered body after the IP treatment. Further, as shown in Table 1, the starting temperature and the ending temperature of the weight decrease become higher with the increase of the addition amount.
The ratio was smaller than in the case of adding nO ₂ , TiO ₂ and ZrO ₂ .

Comparative Example 6 Cr ₂ O ₃ was added to a hematite powder in a molar ratio of 1, 3 and 5 mol%, respectively, and a sintered body was manufactured under the same conditions as in Example 1. Table 1 shows the results of the relative density and thermogravimetric measurement of the obtained sintered body. The relative density of each of the obtained sintered bodies was 99% or more.
Formation of a magnetite layer was observed on the surface of the sintered body after the IP treatment. Further, as shown in Table 1, the starting temperature and the ending temperature of the weight reduction increase with the addition amount,
The ratio was smaller than in the case of adding SnO ₂ , TiO ₂ and ZrO ₂ .

[0035]

As described above, according to the present invention, SnO is used.
_2, 5 mol of at least one of TiO ₂ and ZrO ₂
% Or less, the slider material for a magnetic head obtained by sintering such a raw material is dense and has good friction and wear characteristics with respect to a hard disk, thus improving the reliability of HDD. be able to. In addition, SnO ₂ , TiO ₂ and ZrO are added to hematite.
_By adding at least one of ₂ at 5 mol% or less, the reduction resistance of hematite can be remarkably improved, and the formation of a magnetite layer having magnetism can be suppressed.
Therefore, a magnetic head manufactured using the hematite-based material for a magnetic head of the present invention has good magnetic properties.

Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location G11B 5/255 G11B 5/60 B 5/60 21/21 101K 21/21 101 C04B 35/26 Z

Claims (4)

[Claims] 1. A hematite material for a magnetic head containing Fe ₂ O ₃ as a main component, wherein the Fe ₂ O ₃ contains at least one of SnO ₂ , TiO ₂ and ZrO _{2 in} an amount of 5 mol% or less. Material for magnetic heads. 2. A magnetic head manufactured using the hematite-based material for a magnetic head according to claim 1. 3. The method for producing a hematite-based material for a magnetic head containing Fe ₂ O ₃ as a main component, wherein the Fe ₂ O ₃ contains at least one of SnO ₂ , TiO ₂ and ZrO ₂ at 5 mol% or less. A method for producing a hematite-based material for a magnetic head, comprising sintering the raw material powder. 4. The method for producing a hematite-based material for a magnetic head according to claim 3, wherein the reduction of hematite to magnetite in the heat treatment after HIP or sintering is suppressed.