JPH04251417A - Nonmagnetic substrate for magnetic head - Google Patents

Abstract

PURPOSE:To provide the nonmagnetic substrate for magnetic heads for vapor deposition of metallic magnetic films. CONSTITUTION:This nonmagnetic substrate for magnetic heads is formed by using CoO and NiO or NiO as a basic compsn. and adding at least one kind among the silicides of Ti, Zr, Nb, Ta, Cr, Mo, and W at 0.1 to 1wt.% to this compsn. Characteristics nearly equal to the characteristics of the structural body of the magnetic film in both of coefft. of thermal expansion and hardness are obtd. with the nonmagnetic substrate of this compsn. The peeling of the structural body of the magnetic film and the generation of cracks are, therefore, drastically prevented. The shortened life of the magnetic head and the deformation, crack, etc., of the nonmagnetic substrate are suppressed by increasing the hardness. This substrate has the advantage that the substrate is particularly excellent in the wear resistance and durability of the heads.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonmagnetic substrate for a magnetic head on which a metallic magnetic film is deposited.

0002

BACKGROUND OF THE INVENTION Conventionally, barium titanate, calcium titanate, alumina, etc. have been used for this type of use. However, since its coefficient of thermal expansion was significantly different from that of the magnetic film structure, the deposited magnetic film structure was likely to peel off, and the difference in coefficient of thermal expansion caused stress and cracks.

Furthermore, conventional materials have low hardness, and especially when a high coercive force tape (so-called metal tape) is used, the hardness and wear resistance of the nonmagnetic substrate are different from those of the magnetic film structure. There was a problem in that the friction generated by sliding with the magnetic tape caused uneven wear and the like, resulting in changes in magnetic properties. In particular, when the hardness is low, the disadvantages are that the life of the magnetic head is shortened or that the nonmagnetic substrate is deformed, cracked, or peeled off.

The present inventors have conducted research on oxide ceramics in order to solve the above-mentioned drawbacks, and have
It has already been disclosed that oxides having a basic composition of O or NiO are effective. (JP 01-287811, JP 02-168602, JP 01-214206) Furthermore, we investigated additives to improve hardness and density.
The basic composition is oO, NiO, and one or more of manganese oxide, titanium dioxide, alumina, and calcia at 0.1~
When adding 5 wt%, and when adding one or more of 1 to 5 wt% yttria, 0.1 to 1% titanium nitride, 0.3 to 2 wt% boron oxide, or 1 to 5 wt%
The effectiveness of adding wt% silicon dioxide was confirmed and these were disclosed. (JP 02-94408, JP 01-159622, JP 01-214208)

0
005]

[Means for Solving the Problems] In order to solve the above problems, the present inventors have developed a method using CoO and NiO or Ni.
As a result of further investigation into additives with O as the basic composition, we found that the composition contained Ti, Zr, Nb, Ta, Cr, Mo,
0.1 to 1 wt% of at least one type of W silicide
It has been found that when added, the above characteristics are satisfied. Therefore, specifically, the object of the present invention is to have a thermal expansion coefficient close to that of a deposited magnetic film structure, high Vickers hardness,
Furthermore, it is an object of the present invention to provide a material that does not cause excessive chemical erosion reactions between other head constituent materials.

[0006]

[Structure of the Invention] That is, the present invention uses CoO and NiO or NiO as a basic composition, and Ti,
Provided is a nonmagnetic substrate for a magnetic head, characterized in that 0.1 to 1 wt% of at least one of silicides of Zr, Nb, Ta, Cr, Mo, and W is added.

[0007]

DETAILED DESCRIPTION OF THE INVENTION In order to facilitate understanding of the present invention, the present invention will be explained specifically and in detail. The basic composition means an oxide of NiO alone or a composite oxide of NiO and CoO, for example, CoO/NiO (molar ratio) = 0/100 to 80/
20, more preferably CoO/NiO (molar ratio)=
3/97 to 60/40.

[0008] For the above composition, the present invention provides Ti, Z
At least one of silicides of r, Nb, Ta, Cr, Mo, and W is added in an amount of 0.1 to 1 wt%. Ti, Zr,
Silicides of Nb, Ta, Cr, Mo, and W are substances that have the effect of suppressing grain growth, and when added in an amount of 0.1 wt% or more, the grain size is suppressed and densification is promoted. Therefore, although the relative density is high and the hardness is improved, it is excellent in machining. However, the coefficient of thermal expansion is lower than that of NiO and CoO, and if the amount added exceeds 1 wt%, it becomes difficult to adjust the coefficient of thermal expansion. Moreover, if it exceeds 1 wt%, the formation of a liquid phase is observed at the grain boundaries during sintering, and as the grain size increases, the grain boundary strength decreases, and the mechanical strength deteriorates. It is effective to add it alone or in combination with previously disclosed additives. It is desirable to adopt a combination that corresponds to the desired hardness and coefficient of thermal expansion.

Next, a method for manufacturing the substrate will be described. Commercially available oxides and silicides are used as raw materials, weighed to give the desired composition, and mixed in 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 is performed, calcined at 850 to 1100°C in Ar, for example, and then pulverized using a coarse crusher to obtain 100 to 200
Sieve with a μm sieve. The calcined powder is further treated in a wet ball mill in ethanol for 20 to 72 hours to reduce the
Finely pulverize to less than m. After granulating this, it is subjected to CIP molding, sintered at 1230 to 1400°C in oxygen, for example, and then H
Performs IP processing. HIP processing conditions are 80-120M
Pa, 1200-1350°C, 1-2 hours is desirable.

[0010] It has been confirmed that the sintered body thus obtained has a dense, rock-salt-type structure, and is superior to conventional materials in that there is less friction caused by sliding of the tape and less chipping of edges. did it.

Examples of the present invention will be described below.

[Example 1] CoO/NiO (
Molybdenum disilicide (Mo silicide) was mixed therein as an additive as shown in Table 1. Mixing was carried out in a wet ball mill in ethanol for 20 hours. Add this mixed powder to 1000 ml of Ar
After calcining at ℃, the mixture was pulverized in an ethanol wet ball mill for 40 hours. This pulverized powder was sintered at 1350° C. in oxygen after CIP molding. This was subjected to HIP treatment at 1250° C., 100 MPa, and 1 hour. The relative density of the sintered body was over 99%.

Table 1 shows the physical properties of the sintered body of this example. As physical property values, thermal expansion coefficient (α: μm/m° C.) and Vickers hardness (Hv) were selected.

[0013] As a comparative example, the physical property values are also shown when the basic composition is the same as that of barium titanate, which is a conventional material, but the amount of additives is changed.

[Table 1] * indicates a comparative example. The coefficient of thermal expansion is approximately determined by the basic composition, and is 13.8±0.2 μm/m° C. in the range of this example. This value is approximately equivalent to that of the magnetic film structure. Therefore, from Table 1, the amount of silicide added must be within 1 wt%.

[0014]

[Example 2] CoO/NiO (
The composition was adjusted to have a molar ratio of 35/65, and tungsten disilicide (W silicide) was mixed therein as an additive as shown in Table 2. Mixing was carried out in a wet ball mill in ethanol for 20 hours. Add this mixed powder to 1000 ml of Ar
After calcining at °C, the mixture was pulverized in an ethanol wet ball mill for 40 hours. This pulverized powder was sintered at 1350° C. in oxygen after CIP molding. This was subjected to HIP treatment at 1250° C., 100 MPa, and 1 hour. The relative density of the sintered body was over 99%.

Table 2 shows the physical properties of the sintered body of this example. As the physical property values, the coefficient of thermal expansion and Vickers hardness were selected as in Table 1.

[0016] As a comparative example, the physical property values are also shown when the basic composition is the same as that of barium titanate, which is a conventional material, but the amount of additives is changed.

[Table 2] * indicates a comparative example. The coefficient of thermal expansion is approximately determined by the basic composition, and is 13.8±0.2 μm/m° C. in the range of this example. This value is approximately equivalent to that of the magnetic film structure. Therefore, from Table 2, the amount of silicide added must be within 1 wt%.

[0017]

As explained above, (1) the non-magnetic substrate of the present composition can obtain properties almost equivalent to those of the magnetic film structure in terms of coefficient of thermal expansion and hardness. Therefore, peeling and cracking of the magnetic film structure can be significantly prevented.

(2) Furthermore, by increasing the hardness, it is possible to shorten the life of the magnetic head and suppress deformation and cracking of the non-magnetic substrate, which has the advantage that the head has particularly excellent wear resistance and durability. .

Claims (1)

[Claims] Claim 1: CoO and NiO or NiO are the basic compositions, and Ti, Zr, Nb, T
1. A nonmagnetic substrate for a magnetic head, characterized in that 0.1 to 1 wt% of at least one of silicides of a, Cr, Mo, and W is added.