JPH05319895A - Nonmagnetic ceramics for magnetic head - Google Patents

Abstract

PURPOSE:To provide nonmagnetic ceramics for a magnetic head having a high coefft. of thermal expansion and excellent in various characteristics such as mechanical strength, wear resistance and workability. CONSTITUTION:A base consisting of 20-80mol% MgO and the balance NiO is prepd., 0.1-5.0wt.% TiO2 is added to 100 pts.wt. of the base and 0.1-10.0wt.% at least one among Nd2O3, Pm2O3, Eu2O3 and Gd2O3 is further added to produce the objective nonmagnetic ceramics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic ceramic for a magnetic head used for a magnetic head of a floppy disk device, a hard disk device, a VTR, etc., which is a peripheral device of a computer, for example.

[0002]

2. Description of the Related Art A reader for writing and reading information on a magnetic recording medium such as a computer, a VTR, or an audio device (mainly a cassette deck) has a magnetic head. The magnetic head is manufactured by glass-bonding ferrite, which is a magnetic material, and ceramics, which is a non-magnetic material. Further, particularly in the case of a thin film magnetic head, it is manufactured by forming a magnetic thin film on a magnetic or non-magnetic ceramic substrate by vapor deposition or sputtering. Furthermore, a laminated head in which a metal magnetic film is sandwiched between non-magnetic ceramic substrates has also been developed.

On the other hand, in recent years, the digital-compatible magnetic head, which has been remarkably developed and researched, is required to be further downsized, high-density recording, and high quality in accordance with the technological transition to high-density recording of the recording medium. ing. Therefore, ferrite is required to have a large saturation magnetic flux density in order to adapt to the characteristics of the recording medium. In order to give ferrite the magnetic characteristics of high saturation magnetic flux density, it is necessary to manufacture it in a composition region having a large thermal expansion coefficient.

Further, the thin film magnetic head has a high saturation magnetic flux density and a high coefficient of thermal expansion (130 to 140 × 10 ⁻⁷ / ° C.).
It is manufactured by depositing a metal magnetic thin film of permalloy, sendust, or the like having the above-mentioned properties on a ceramic substrate. When manufacturing such a thin-film magnetic head, a process of bonding different materials by adhesion, vapor deposition, or sputtering is required. At this time, the thermal expansion coefficient of the constituent materials should be approximate, and the strain generated during bonding should be reduced. It needs to be minimized.

By the way, as described above, the non-magnetic ceramic material provided in the magnetic head by being integrally formed with the magnetic material includes CaTiO ₃ system and BaTiO ₃ .
₃ series, Zn ferrite series, or Al ₂ O ₃ —TiC series are used.

[0006]

In the case of the conventional non-magnetic ceramic material for magnetic head, the coefficient of thermal expansion (α) is (7).
Many of them are in the range of 5 to 120) × 10 ⁻⁷ / ° C., and it is very difficult to produce nonmagnetic ceramics having a coefficient of thermal expansion of 130 × 10 ⁻⁷ / ° C. or more.

On the other hand, the thermal expansion coefficient (α) of the magnetic material
Is relatively high as described above (130 to 140 × 10 ⁻⁷ / ° C.). Therefore, the current magnetic head has to be manufactured with a material configuration having a coefficient of thermal expansion that is not approximate,
There is a problem that the strain generated at the time of joining cannot be sufficiently suppressed.

Under these circumstances, the nonmagnetic ceramics for magnetic heads are generally required to have the following characteristics. That is, 1) high density and few pores, 2) excellent wear resistance, 3) excellent workability, 4) thermal expansion coefficient is similar to that of magnetic material,
5) High resistivity, 6) Physically and chemically stable, etc.

The present invention has been made to solve such a problem, and the first technical problem is to have a large thermal expansion coefficient in order to adapt to a magnetic material having a large thermal expansion coefficient.
An object of the present invention is to provide a non-magnetic ceramic for a magnetic head which has excellent wear characteristics and good workability.

A second technical object of the present invention is to provide a high density non-magnetic ceramics which can adjust the coefficient of thermal expansion by a composition ratio, is excellent in mechanical strength and workability, and can be easily manufactured. To provide.

[0011]

According to the present invention, (20
˜80) mol% MgO and the balance NiO to 100 parts by weight of the main component (0.1 to 5) wt% TiO _2.
While adding Nd ₂ O ₃ , Pm ₂ O ₃ , Eu
₂ O _3, and at least one of Gd ₂ O ₃ (0.1~10) is non-magnetic ceramic for a magnetic head that is prepared by adding wt% is obtained.

[0012]

The non-magnetic ceramic material of the present invention is noted that when the oxides MgO and NiO having a large coefficient of thermal expansion are solid-dissolved as a whole (total ratio), a stable uniform component is formed. The inventors of the present invention first examined the composition ratios of MgO and NiO, which are the main components of non-magnetic ceramics, and found that those having a coefficient of thermal expansion (α) of α ≧ 130 × 10 ⁻⁷ / ° C. , It was analyzed that the MgO component was obtained at 80 mol% or less.

If the MgO component is less than 20 mol% (that is, NiO exceeds 80 mol%), the magnetic permeability exceeds 2, which is unsuitable as a nonmagnetic ceramic for a magnetic head. Also, MgO is (20-80) mol%
The coefficient of thermal expansion is 130 × 10 ^-7 / ° C.
As described above, under the sintering temperature condition of 1400 ° C., not only the porosity becomes large and the densification becomes insufficient, but
It has been found that the hardness is also low, which makes it unsuitable as a ceramic material for magnetic heads.

Therefore, the present inventors have added TiO ₂ to MgO and NiO, which are the main components of non-magnetic ceramics, and added Nd ₂ O ₃ , Pm ₂ O ₃ , Eu ₂ O ₃ , and G.
It has been found that these problems can be improved by adding at least one of d ₂ O ₃ . That is, when TiO ₂ is added in the range of (0.1 to 5) wt% as an auxiliary component, the hardness of ceramics is enhanced, and Nd ₂ which has an effect of promoting sintering and miniaturization of crystals is further added.
When at least one of O ₃ , Pm ₂ O ₃ , Eu ₂ O ₃ and Gd ₂ O ₃ is added in the range of (0.1-10) wt%,
The porosity and hardness of ceramics can be improved.

The reason why the range of addition of the subcomponents is limited is that if the content of TiO ₂ is less than 0.1 wt%, the hardness becomes small, and if it exceeds 5 wt%, the thermal expansion coefficient becomes small. Nd ₂ O ₃ , Pm ₂ O ₃ , Eu ₂ O
_This is because the porosity becomes large even if the content of at least one of ₃ and Gd ₂ O ₃ is less than 0.1 wt% or exceeds 10 wt%.

[0016]

EXAMPLES The nonmagnetic ceramics for magnetic heads of the present invention will be described in detail below with reference to examples. First, the manufacturing process of non-magnetic ceramics will be briefly described.

First, commercially available raw materials MgO, NiO,
_{TiO 2, Nd 2 O 3,} Pm 2 O 3, Eu 2 O 3, and prepares a Gd ₂ O _3, were weighed each of these components so that the composition ratio shown in Table 1, in the dispersion medium Mix with a ball mill using alcohol.

[0018]

[Table 1]

Here, MgO and NiO are the main components, and TiO ₂ , Nd ₂ O ₃ , Pm ₂ O ₃ , Eu ₂ O ₃ ,
And Gd ₂ O ₃ are both subcomponents.

Subsequently, the mixture was dried, then calcined in the air at a temperature of 1200 ° C. for 2 hours, and then pulverized again with a ball meal. Here, the average particle size of the powder after pulverization is 1.2 μm.

Further, 1 wt% of binder is added to the powder mixture.
After adding and granulating, molding was performed at a pressure of ² ton / cm ² , and sintering was performed in air at a temperature of 1400 ° C. for 3 hours. As a result, a sintered body having a relative density of 97% or more was installed in an alumina crucible, and the temperature was 1300 ° C. and the pressure was 1000 kg / cm ² in an Ar gas atmosphere.
Hot isostatic pressing (H
IP) treatment.

No. 1 shown in Table 1 1-No. Each non-magnetic ceramic sample 13 was obtained by the above steps. Table 1 shows the coefficient of thermal expansion in the temperature range of 100 to 400 [° C.], the Vickers hardness, the bending strength, the average grain size, the porosity, which are measured under the load condition of 500 g, for each of the sample non-magnetic ceramics. And the characteristic results of measuring the magnetic permeability are shown. However, a magnetic head is constructed by preparing a toroidal core having a magnetic permeability of (outer diameter φ) 10 × (inner diameter φ) 6 × (thickness) 2 [mm] and a frequency of 1 k.
It is measured under the condition of Hz.

According to the characteristic results, the sample No. 1-No.
Each sample non-magnetic ceramics suitable for the present invention up to 7 and sample No. 8 to No. As is clear from comparison with the comparative examples up to 13, when MgO exceeds 80 mol% (No. 13), the coefficient of thermal expansion decreases, and when MgO is 20%.
It can be seen that the magnetic permeability increases when the amount is less than mol% (No. 12). Further, when the content of TiO ₂ is less than 0.1 wt% (No. 11), the hardness decreases, and when it exceeds 5.0 wt% (however, not included in Table 1), the thermal expansion coefficient decreases.

Further, Nd ₂ O ₃ , Pm ₂ O ₃ and Eu ₂ O
₃ and at least one of Gd ₂ O ₃ is 0.1 wt.
When it is less than 10% (No. 8 and No. 10), it is understood that the porosity and the average particle size are large, and the hardness and the bending strength are also reduced accordingly. On the other hand, when it exceeds 10.0 wt% (No. 13), it is found that the porosity is large and the hardness is lowered.

From the above characteristic results, MgO (20 to 20) is a suitable composition condition for the non-magnetic ceramics of the present invention.
80) mol% and TiO ₂ (0.1-5.0) wt% was added to 100 parts by weight of the main component consisting of the balance NiO, and Nd ₂ O ₃ , Pm ₂ O ₃ , and Eu ₂ O ₃ were added. , And Gd ₂ O ₃ (0.1-10.
It was found that 0) wt% should be added.

As a result, the nonmagnetic ceramic thus produced has a coefficient of thermal expansion (α) of α> 130 ×
It was found that a high density non-magnetic ceramic having a fine structure having a fine structure of 10 ⁻⁷ / ° C. was obtained.

[0027]

As described above, according to the present invention, the coefficient of thermal expansion which is difficult to manufacture by the conventional technique is 130 × 1.
High density non-magnetic ceramics of 0 ^-7 / ° C or higher can be easily obtained. This non-magnetic ceramic is excellent in mechanical strength, wear characteristics, and workability, and has an allowable composition ratio. Therefore, the thermal expansion coefficient can be adjusted by the composition ratio, and the manufacturing can be easily performed. There is.

The non-magnetic ceramic according to the present invention is
Since it satisfies the various properties required for it, it is an optimum material for joining with metallic magnetic thin films such as MnZn ferrite, permalloy, and sendust having a high saturation magnetic flux density. This can greatly contribute to the manufacture of a magnetic head with high reliability and quality.

Claims (1)

[Claims] 1. To 100 parts by weight of a main component consisting of (20 to 80) mol% MgO and the balance NiO, (0.1 to 5) wt% of TiO ₂ is added, and Nd ₂ O ₃ and P are added.
A non-magnetic ceramic for a magnetic head, which is produced by adding (0.1 to 10) wt% of at least one of m ₂ O ₃ , Eu ₂ O ₃ , and Gd ₂ O ₃ .