JPH0380412A - Nonmagnetic substrate for magnetic head - Google Patents

Abstract

PURPOSE:To obtain the nonmagnetic substrate material for a magnetic head which has the characteristics of >=150X10<-7>/ deg.C coefft. of thermal expansion and 500 to 700 deg. Vickers hardness and is suppressed in chemical erosion reaction by using the oxide of a compsn. which is expressed by specific formula and has a rock salt type structure as a basic compsn. CONSTITUTION:The material which has the characteristics of >=150X10<-7>/ deg.C coefft. of thermal expansion and 500 to 700 deg. Vickers hardness and does not induce the excessive chemical erosion reaction with other head constituting materials is obtd. by using the oxide of the compsn. which is expressed by the formula and has the rock salt structure as the basic compsn. of CoO-NiO ceramics. The characteristics in both coefft. of thermal expansion and hardness, nearly equiv. to the characteristics of the structural body of a magnetic film are obtainable with the nonmagnetic substrate consisting of this compsn. and, therefore, the peeling and cracking of the structural body of the magnetic film are, therefore, greatly prevented and the shortening of the life of the magnetic head and the deformation and cracking of the nonmagnetic substrate material are suppressed.

Description

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

Prior Art Conventionally, barium titanate,
Calcium titanate, alumina, etc. were used. However, since the coefficient of thermal expansion is significantly different from that of the magnetic film structure, the deposited magnetic film structure is likely to peel off, and the difference in coefficient of thermal expansion may generate stress and cause cracks.

Furthermore, conventional materials have low hardness, and especially when high coercive force tape (so-called metal tape) is used, the non-magnetic substrate has a different hardness and abrasion resistance than the magnetic film structure, and the sliding with the magnetic tape is difficult. There is a problem in that the friction generated by the movement causes uneven wear and 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.

In order to solve the above-mentioned drawbacks, the inventors of the present invention have developed Coo-Ni.
Cox has been conducting research on 0-series ceramics.
It has already been disclosed that an oxide having a composition of N i, -xo (light output 0.2≦X≦1.8) is effective.

However, depending on the manufacturing process of the metallic magnetic film structure and its uses, a nonmagnetic substrate having a higher coefficient of thermal expansion has become necessary.

Problems to be Solved by the Invention The present invention solves the above-mentioned drawbacks, specifically 1.
The purpose is to provide a material that has a coefficient of thermal expansion of 7°C or more, a Vickers hardness of 500 to 700, and does not cause excessive chemical erosion reactions between other head constituent materials. be.

Structure of the invention, that is, the present invention provides CoxN i2-xO2 (where O≦
The present invention relates to a nonmagnetic substrate for a magnetic head, which is expressed by x<0.2) and has a rock salt structure.

Means and Effects for Solving Problems The present inventors have been conducting research on COO-NiO ceramics for some time, and after considering it from the above perspective, the basic composition is CoxN i, -xo, (but 0
It has been found that an oxide having a composition of ≦X0.2) is effective.

In Coo-Ni0 series ceramics, the coefficient of thermal expansion is approximately determined by the following equation.

α(CN) =α(C) M (C) 10α(N)M
(N) (However, B indicates the coefficient of thermal expansion, M indicates the mole fraction, C in parentheses indicates Coo, N indicates NiO, and CN indicates the C0O-NiO system.) Apply this formula. Then, 150xl
In order to obtain a coefficient of thermal expansion of 7° C. or higher, the composition of the present invention (0≦x<0.2) is required.

Commercially available oxides are used as raw materials, weighed to give the desired composition, and mixed using a ball mill.

Mixing is carried out for example in a wet ball mill in ethanol for 10 to 30 minutes.
Do time.

After drying, C, IP molding is performed, for example, 850 to 110 in Ar.
Calcined at 0℃, then crushed using a coarse crusher,
Sieve with a 200 μm sieve.

The calcined powder is further processed, for example, in a wet ball mill in ethanol for 2
Treat for 0 to 72 hours and pulverize to 1 μm or less.

After granulating this, CIPIP molding, for example, N.

Sintering is performed at a temperature of 1230-1400°C, followed by HIP treatment. HIP processing conditions are 800-1200kg/
crl! , 1200-1350°C for 1-2 hours.

The sintered body thus obtained has a dense, rock salt-type structure, and exhibits less friction due to sliding of the tape and less chipping of the etched areas (which is superior to conventional materials).

Also, CoxN i2-xO2 (0.2≦X≦1
．． As in the case of 8), Mn○, T i O.

Al, 01, Cab, Y, O,, TiN% B, O,,
Additives such as S i O, etc. are effective.

Examples of the oxides shown in Table 1 among the oxides represented by the compositional formula CoxN i, -xo, which can be added singly or in combination, and it is desirable to adopt a combination that corresponds to the desired hardness and coefficient of thermal expansion. The one with the composition of Nip, C.

Adjusted from O. The mixture was wet ball milled in ethanol for 22 hours.

After drying, after calcination at 1000℃ in CIPIP molding Ar, 1
It was ground to 50 μm or less.

The calcined powder was further treated with a wet ball mill in ethanol for 70 hours to be finely ground to 1 μm or less.

This was granulated, arp molded, and sintered at 1400°C in N. Note that the density of the sintered body was high even without HIP treatment.

X-ray diffraction of the sintered body confirmed that it had a rock salt type structure.

Table 1 shows the relative density, Vickers hardness (Hv), and coefficient of thermal expansion (α) of the sintered body. In the table, the characteristics of barium titanate (Titabari) are also listed as a comparative example.

Table 1 As described in detail of the invention, (1) the nonmagnetic substrate of the present composition can obtain properties substantially 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) Further, 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, and there is an advantage that the head has particularly excellent wear resistance and durability.

Claims (1)

[Claims] Co_xNi_2_-_xO_2 (0≦x<0
．． 2) A non-magnetic substrate for a magnetic head characterized by having a rock salt type structure