JPS62137709A - Nonmagnetic ceramics for magnetic head - Google Patents

Abstract

PURPOSE:To easily produce high-density nonmagnetic ceramics having alpha>=130X10<-7>% deg.C coefft. of thermal expansion by incorporating NiO, MgO, TiO2, and MnO therein. CONSTITUTION:This ceramics contains 100pts.wt. essential component consisting of 10-70mol% MgO, 20-80mol% NiO, 1-5mol% TiO2, and 5-20mol% MnO. The content of NiO is obtd. at >=20mol% in order to obtain alpha>=130X10<-7>% deg.C. However, sintering is extremely difficult and the ceramics having high porosity is obtd. at 1,400 deg.C sintering temp. if the component ratio of MgO is >=60mol%. The hardness is low and the ceramics having high reliability in the wear charac teristic is not obtainable if the component ratio of NiO is >=70mol%. Magnetic permeability exhibits the value over 2 and such value is inadequate as the nonmagnetic ceramics if the component of NiO exceeds 80mol%. These problems can be improved by simultaneously adding TiO2 and MnO to the ceramics. More specifically, the hardness is improved by compounding TiO2 therewith and the porosity is improved by compounding MnO having the effect of acceler ating the sintering therewith.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Technical Field> The present invention relates to non-magnetic ceramics used as a slider for a magnetic head of a floppy disk device or a hard disk device, which are peripheral devices of computers.

<Prior Art> Magnetic heads for computers, VTRs, or audio devices are generally constructed by glass-dending ferrite, which is a magnetic material, and ceramic, which is a non-magnetic material. In the case of a thin film magnetic head, a magnetic thin film is formed on a magnetic or nonmagnetic ceramic substrate by vapor deposition or sputtering.

In recent years, digital magnetic heads have been required to be smaller, have higher recording density, and have higher quality as the technology advances toward higher density recording of recording media. Therefore, ferrite is required to have a large saturation magnetic flux density in order to suit the characteristics of recording media. In other words, in order for ferrite to have magnetic properties with a high saturation magnetic flux density, it must be manufactured in a composition range that has a large coefficient of thermal expansion.

In addition, in the case of a thin film head, the thermal expansion coefficient is 130 to 140 x 10, which has high saturation magnetic flux density and high magnetic permeability.
It is manufactured by depositing a permalloy or sendust metal thin film with a large %C on a ceramic substrate. These different types of materials are bonded or vapor-deposited.

In the case of constructing and manufacturing with vines, it is necessary to approximate the coefficient of thermal expansion of the constituent materials and to minimize the strain generated during bonding.

Conventionally, non-magnetic ceramics that are integrated with the above-mentioned magnetic material have been CaTiO3 ceramics or BaTiO3 ceramics.
Type 3 ceramics are used. However, the coefficient of thermal expansion of these ceramics is 80~120X10''-
It is extremely difficult to produce ceramics that exhibit a coefficient of thermal expansion of 130 x 10-7% or more.

Generally, the following requirements are required for non-matrix ceramics for magnetic heads.

1) High density and few pores.

2) Excellent wear resistance properties.

3) Excellent workability.

4) The coefficient of thermal expansion is similar to that of a magnetic material.

5) High resistivity.

6) Stable to physical and chemical treatments.

Means for Solving the Problems> In view of the above problems, the present invention has a large coefficient of thermal expansion (α) in order to adapt to a dielectric material having a large coefficient of thermal expansion (α).

The present invention provides nonmagnetic ceramics for magnetic heads that have good wear characteristics and good workability. The present inventors focused on the fact that the oxides MgO and NiO, which have large coefficients of thermal expansion, are completely dissolved in solid solution to form a stable and uniform component.

The purpose is to easily produce high-density non-magnetic ceramics whose thermal expansion coefficient is controlled by the composition ratio and which has excellent mechanical strength and workability.

Fig. 1 shows NiO
This figure shows the value of the coefficient of thermal expansion α between 100°C and 400°C when two components, MgO and MgO, are mixed. α≧130X1
In order to obtain 0%℃, the NiO content must be 20mol11
It can be seen that the above results can be obtained. However, MgO is 6
If the component ratio is 0 mo1% or more, sintering becomes extremely difficult, and a sintering temperature of 1400° C. results in a ceramic with high porosity. Furthermore, if the NiO content is 70 mo1% or more, the hardness will be low and a ceramic with highly reliable wear characteristics cannot be obtained.

Furthermore, if the NiO content exceeds 80 mai1%, the magnetic permeability will exceed 2, making it unsuitable as a non-magnetic ceramic. The present inventors solved these problems by using TiO2 and Mn.
It has been found that this can be improved by adding O at the same time. That is, T102 is added to increase the hardness, and MnO, which has a sintering accelerating effect, is added to improve the porosity.

Figure 2 shows that NiO is 40 mol % e MgO is 60 mol %
The values of Vickers hardness HV (load 500 g) and thermal expansion coefficient (α) when TiO2 is blended into the matrix containing 1% mai are shown. Similarly, FIG. 3 shows the relationship when MnO is mixed. TiO2 has a remarkable effect on improving Hv, but as its content increases, it greatly reduces the value of α. In order to make the α value 130×10%° C. or higher, the limit for the content of TiO2 is 5 mai1%.

Also, when the MnO content is less than 5 mo1%.

The effect of accelerating sintering is not so pronounced, and if it exceeds 10 mol %, it precipitates at the grain boundaries and lowers Hv, which is not preferable. Furthermore, CaO and Y2O3 added as subcomponents are effective in making crystal grains finer and improving porosity.

<Example> (1) Commercially available raw material 81021029g09T
iO22 was weighed to have the composition ratio shown in Table 1, mixed in a gall mill using alcohol as a dispersion medium, dried, and then calcined in air at a temperature of 1200°C for 2 hours. The calcined powder is pulverized in a ball mill, and the average particle size is 1
．． It becomes 2 μm. After filtration and drying, apply the binder once - Ii1
t% was added, granulated using a Raikai machine, and then 2 t/
Molded at a pressure of α and heated to a temperature of 1400°C in air for 3
Time firing was performed. The sintered body having a relative density of 97 or higher is placed in an alumina crucible and heated to a temperature of 1300°C.
, hot isostatic pressing (HIP) in an Ar gas atmosphere under the conditions of 97 cm at a pressure of 1000 and a holding time of 2 hours.
processed. Table 1 shows the material properties of the obtained samples. As shown in Table 1, as the content of NiO increases, the coefficient of thermal expansion α value increases. Also, by simultaneously blending ITiO□ and MnO.

It was found that both hardness and porosity were improved. The magnetic permeability is a 10φ x 6φ x 2 toroidal core at a frequency of 1 kHz.
z, the number of turns was 25, but NiO80m
When the composition ratio is less than ol %, μi<2, indicating non-magnetic customization. In terms of composition ratio, NiO is 20 to 80 mo1%
, α is 130 with MgO in the range of 10 to 70 mol.
It can be easily controlled up to ~15 ll x 10% °C. Furthermore, by simultaneously blending TiO2 and MnO, it was possible to easily obtain a high-density nonmagnetic ceramic with high Vickers hardness, high resistance, and excellent mechanical properties.

<Example> (2) Ca was added to the powder having the composition ratio of sample A-4 in Table-1.
CO3 was weighed and added to give a concentration of 1.2 wt% in terms of CaO, and 1.5.10 wt% of Y2O3 was similarly added to give the composition ratio shown in Table 2.

A sample was produced under the same manufacturing conditions as in Example-1.

The characteristics were investigated and shown in Table 2. It has been found that both CaO and Y2O6 have a grain size suppressing effect and are effective for obtaining ceramics with a fine grain structure.

However, if the amount of CaO added exceeds 1 wt%, the strength of the crystal grains tends to become weaker and the Vickers hardness decreases, which is not preferable. Furthermore, if Y2O5 exceeds 5wt, the porosity will increase and problems will arise in mirror finishability. Therefore C
By adding O~1 wt% of aO and 1~5 wt% of Y2O5, a high-tolerance nonmagnetic ceramic with a fine grain structure, excellent Vickers hardness and resistance, and good mechanical properties was obtained. .

<Effects of the Invention> As is clear from the above results, according to the present invention, the thermal expansion coefficient α≧130×10−7%, which was conventionally difficult to manufacture.
It was possible to easily produce high-density nonmagnetic ceramics with a temperature of . That is, Mn- has a high saturation magnetic flux density.
It is an optimal material for bonding thin metal films such as Zn ferrite, permalloy, and sendust, and a highly reliable magnetic head could be manufactured.

[Brief explanation of drawings]

Figure 1 is a graph showing the NiO-MgO component ratio and thermal expansion coefficient, and Figure 2 is a graph showing the TsO2 content, hardness, and thermal expansion coefficient n.
FIG. 3 is a graph showing the relationship between the O2 content and the hardness as well as the coefficient of thermal expansion. Figure 1

Claims (1)

[Claims] 1) MgO 10-70 mol%, NiO 20-80 mol%
, TiO_21 to 5 mol %, and MnO_ 5 to 20 mol %, as main components, 100 parts by weight. 2) CuO is further added to the main component described in claim 1.
A non-magnetic ceramic for a magnetic head, characterized in that it contains 1 wt% or less of Y_2O_3 or both of 5 wt% or less.