JPH0612611A - Non-magnetic ceramics for magnetic heads - Google Patents

Abstract

(57) [Summary] [Object] To provide a non-magnetic ceramic for a magnetic head, which is excellent in workability, has a large resistivity, and can easily manufacture a high-density non-magnetic ceramic. [Composition] Cr, Mo, Ta as an additive to Fe ₂ O _3.
0.1 wt% of one or more of the oxides of W and W
% To 5 wt% by adding and sintering,
The crystal grains can be made finer without deteriorating the characteristics of thermal expansion coefficient, hardness, strength, and electric resistance, and the workability is improved.
It is possible to obtain non-magnetic ceramics with little chipping that can be used in magnetic heads.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to non-magnetic ceramics used in magnetic heads of floppy disk devices, hard disk devices, video tape recorders and the like.

[0002]

2. Description of the Related Art A general magnetic head used in a device such as a computer, a VTR or an audio system is constructed by bonding a magnetic core such as ferrite to a ceramic of a non-magnetic material by glass bonding or the like. In the case of a recent thin film magnetic head, a magnetic thin film is formed on a non-magnetic ceramic by vapor deposition or sputtering to form a magnetic head. Furthermore, a laminated head in which a metal magnetic film is sandwiched between non-magnetic ceramic substrates has been developed, and high precision and miniaturization are progressing. In particular, magnetic heads that perform digital signal processing are required to be smaller and have higher performance as the technology for high-density recording on recording media changes. Therefore, it is necessary to form a narrower gap than the conventional magnetic head, and in addition to the magnetic core material, a ceramic that is a nonmagnetic base material is required to be a material that can withstand fine precision processing. Conventionally, the non-magnetic ceramics used by integrally bonding with the magnetic core material are CaTiO ₃ system and BaT.
iO ₃ system, Zn ferrite, Al ₂ O ₃ -TiC based ceramic or the like have been used often.

[0003]

However, the conventional CaTiO ₃ series and BaTiO ₃ series are not suitable for fine processing because chipping easily occurs during processing. Further, although the Zn ferrite type and the Al ₂ O ₃ —TiC type have less chipping during processing, they have the drawback of low electrical resistivity. That is, high density and few pores, excellent wear resistance, excellent workability, thermal expansion coefficient close to that of magnetic material, high resistivity, physical, chemical The non-magnetic ceramics used for magnetic heads are required to have properties such as stability. Therefore, in view of the above-mentioned drawbacks, a technical problem of the present invention is to provide a non-magnetic ceramic for a magnetic head, which is excellent in workability, has a large resistivity, and can easily manufacture a high-density non-magnetic ceramic.

[0004]

In order to solve the above-mentioned problems, the present inventor uses Fe ₂ O ₃ which is one component of ferrite as a starting material to appropriately select an additive to determine the crystal grain size. We have investigated materials that can be controlled and easily produce high-density non-magnetic ceramics with little chipping during processing and excellent workability. Ferrite whose main component is iron oxide (Fe ₂ O ₃ ) can be easily sintered, has a relatively high resistivity, and has properties relatively close to those of the magnetic material that forms the magnetic head core. Suitable as a ceramic material. However, if the Fe ₂ O ₃ material is simply sintered, chipping easily occurs during processing, there is a problem in workability, and it is unsuitable as a non-magnetic ceramic for a magnetic head. As a result of various studies to overcome the problem, it was found that the addition of one or more oxides of Cr, Mo, Ta, and W reduces the occurrence of chipping during processing.

That is, the above-mentioned additive is added from 0.1 wt% to 5 w
It has been found that the addition of one or more t% has an effect of promoting sintering and an effect of refining crystals, and a non-magnetic ceramic for magnetic head having desired characteristics can be obtained.
Further, it was found that if the content of the additive is 0.1 wt% or less, it has no effect on the sintering promotion effect and the refinement of the crystal, and if it exceeds 5 wt%, the porosity becomes large, which is unsuitable as a non-magnetic ceramic for a magnetic head. It was

As described above, the present invention is based on the main component Fe ₂ O ₃ ,
A non-magnetic ceramic for a magnetic head, characterized in that 0.1 wt% to 5 wt% of one or more selected from the group of oxides of Cr, Mo, Ta and W is added.

[0007]

[Function] As an additive to Fe ₂ O ₃ , 0.1 wt% of one or more of Cr, Mo, Ta and W oxides is added.
To 5 wt% and sintered, the crystal grains can be made fine without deteriorating various characteristics such as thermal expansion coefficient, hardness, strength, and electric resistance, workability is improved, and less chipping occurs. A non-magnetic ceramic that can be used in a magnetic head is obtained.

[0008]

EXAMPLES Examples of the present invention will be described below. As an example, commercially available raw material Fe ₂ O ₃ was added to Cr ₂ O ₃ , MoO ₃ , T
Examples of the present invention in which the additives of a ₂ O ₅ and WO ₃ are shown in Samples 2 to 16 of Table 1 and Samples 1 and 17 to 21
In the comparative example, the additives were weighed so as to have the composition ratios shown in Table 1, wet-mixed in a ball mill for 24 hours, added with 1 wt% of a PVA-based binder, and granulated with a spray dryer. 1.0g of these granulated powders
Molded at a pressure of on / cm ² and 1100 in air
Sintering was performed at ℃ for 3 hours. 1 more of the obtained sintered body
A hot isostatic pressing (HIP) treatment was performed in an Ar gas atmosphere under the conditions of 100 ° C., a pressure of 100 MPa, and 2 hours.

[0009]

[Table 1]

Using the samples obtained by the above steps, the coefficient of thermal expansion (100 to 400 ° C.), Vickers hardness (load of 500 g), bending strength, average particle size, porosity,
The resistivity and the chipping occurrence rate were measured. The chipping occurrence rate was measured by an optical microscope for chipping of 2 μm or more generated at the ridge when the sample was mirror-finished and grooved with a # 800 grindstone. In the comparative example, when the additive-free sample 1 and the samples 2 to 16 of the examples of the present invention are compared, Cr is
_It can be seen that one or two or more kinds of ₂ O ₃ , MoO ₃ , Ta ₂ O ₅ , and WO ₃ are within the range of 0.1 wt% to 5 wt% and the crystal grain size becomes finer, and chipping generated during processing is small. However, in the case of Samples 17 and 18 in which the amount of the additive is less than 0.1 wt%, the grain size does not become finer and chipping often occurs during processing. Further, it can be seen that when the addition amount of the sample 19 to the sample 21 exceeds 5 wt%, the porosity increases and the Vickers hardness and the bending strength decrease.

As described above in the examples, the main component Fe ₂
Addition of one or more oxides of Cr, Mo, Ta and W to O ₃ in an amount of 0.1 wt% to 0.5 wt% results in a fine structure with less chipping during machining and excellent workability. A high density non-magnetic ceramic was obtained.

[0012]

As is clear from the above results, according to the present invention, it is possible to easily obtain a non-magnetic ceramic for a magnetic head, which is excellent in workability, has a large resistivity, and has a high density.

Claims (1)

[Claims] 1. Cr, Mo, T with respect to the main component Fe ₂ O ₃
A non-magnetic ceramic for a magnetic head, which is obtained by adding 0.1 wt% to 5 wt% of one or more selected from the group of oxides a and W.