JP2853340B2 - Non-magnetic ceramic material for magnetic head and method of manufacturing the same - Google Patents

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 material for a magnetic head used as a slider or a spacer which is indispensable for various magnetic heads such as a floppy disk head and a hard disk head, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, non-magnetic ceramic materials as slider materials have been required to have higher densities in accordance with the remarkable progress of high density and high reliability of magnetic recording.

By the way, when a conventional magnetic head is manufactured,
Bonding Mn-Zn ferrite core and slider with glass
Is generally used, and the coefficient of thermal expansion of the
Due to core crack and core distortion during bonding due to differences
Thermal expansion at 25-350 ° C to prevent deterioration of magnetic properties
Number 110-128 (× 10^-7/ ° C)
_Three・ SrTiO_ThreeWas used as a main component.
In addition, this CaTiO _ThreeAnd SrTiO_ThreeSolid solution composition and heat
Regarding the relationship between the expansion coefficients, see JP-A-52-30162.
It is detailed in the gazette.

However, densification of this titania in normal-pressure sintering is insufficient, and a production method based on the HIP sintering method which gives priority to achieving high densification has been used.

[0005]

In such a conventional non-magnetic ceramic material, when the HIP sintering method is used, 1
This is a firing method using a high-pressure gas of 000 kg / cm ² or more. The high-pressure gas is obtained by increasing the pressure of a reducing gas such as Ar filled in the initial stage of heating by heating. That is, H
The dense sintered body by IP firing is prepared by first preparing a sintered body having a certain degree of denseness produced by normal-pressure firing called primary firing, then performing HIP firing, and then heat-treating in an oxidizing atmosphere. Obtained by: Thus H
IP calcination requires more steps than normal pressure calcination, and is expensive because the equipment is used for high temperature and high pressure. This is advantageous for high densification, but has a problem of high cost.

An object of the present invention is to provide a non-magnetic ceramic material for a magnetic head which can be manufactured by a normal pressure firing method, which is advantageous in cost, and a method of manufacturing the same.

[0007]

Means for Solving the Problems The present invention to achieve the above object, a composition containing a phosphorus pentoxide (P ₂ O ₅₎ and silicon dioxide (SiO ₂₎ as an additive, and the P ₂
When the mole% of O ₅ is X and the mole% of SiO ₂ is Y, the following ratios 1.5 ≦ X ≦ 40 <Y ≦ 3 Y ≦ −2X + 8 are satisfied and firing is performed.

[0008]

According to the present invention, (αCaTiO ₃ -β
SrTiO ₃ ) −γTiO ₂ (α + β + γ = 1, 0.1
7 ≦ α ≦ 0.60, 0.38 ≦ β ≦ 0.81, 0 ≦ γ ≦
0.02), the densification of the main composition consisting of a mixed solution of CaTiO ₃ and SrTiO ₃ and TiO ₂
By setting the ratio of O ₂ and P ₂ O ₅ to an appropriate value, it can be increased by the liquid phase at the time of firing generated.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to (Table 1) to (Table 3) and FIG.

First, commercially available powder having an average particle diameter of 0.5 μm or less and a purity of 99% or more was used for CaCO ₃ .SrCO ₃ .TiO ₂ . As SiO _2, a commercially available powder having an average particle size of 0.02 μm or less and a purity of 99.9% or more was used. As the P (phosphorus) compound, a primary reagent of H ₃ PO ₄ was used. The samples were weighed to the compositions shown in (Table 1) and (Table 2), and wet-mixed with water in a ball mill for 6 hours.

[0011]

[Table 1]

[0012]

[Table 2]

After drying, calcination was performed at a temperature of 1050.degree. C. or 1140.degree. C. and in an air atmosphere for 6 hours as shown in Table 1 using opaque quartz baking soda and an electric furnace. Samples NO1, NO21, NO22, NO shown in Table 1
It is known that the composition of the calcined powder of 42, NO43 and NO63 becomes the main composition of the non-magnetic ceramic material for a magnetic head according to the following reaction formulas (1), (2) and (3). It is a fact.

[0014]

Embedded image

The calcined powders of Samples NO21, NO42 and NO63 were crushed by a jet mill pulverizer to an average particle size of 0.5 μm.
m, weighed to the composition shown in (Table 2) using the crushed powder and additives, similarly wet-mixed with water in a ball mill for 6 hours, dried, and similarly calcined at 1140 ° C. Was done.

Next, this calcined powder was pulverized with a ball mill for 8 hours using an anionic dispersant, a PVA binder and water, and dried and granulated by a centrifugal spray type granulator. Further, this granulated powder was molded at a pressure of 1 ton / cm ² ,
The sintering was performed at 0 ° C. and 1315 ° C. in an oxygen atmosphere or an air atmosphere. The firing is performed by heating to the maximum temperature at a heating rate of 150 ° C./Hr in an atmosphere in which air / oxygen gas is circulated in a tubular furnace, and then maintaining the temperature for 3 hours.
The system was cooled to 00 ° C. or less.

The densification of the obtained sample was evaluated based on the porosity obtained from the distribution of pores on the polished surface of the cut sample which had been wet lap finished using 3 μm diamond powder. The coefficient of thermal expansion of the sample is 25 to 3 by the differential expansion method.
It was determined from the average coefficient of linear thermal expansion at 50 ° C.

The porosity and coefficient of thermal expansion of the obtained sample are shown in Table 3.

[0019]

[Table 3]

As an example of the additive ratio of the additive in the main composition having the same composition, the additive ratio of the additive in Samples 1 to 20 is shown. (Table 1), (Table 2), (Table 3) and FIG.
According to the results of the above, an oxygen atmosphere was prepared by using additives SiO ₂ and H ₃ PO ₄ and main components CaCO ₃ , SrCO ₃ and TiO ₂ ,
It is clear that a sintered body having a very dense and necessary thermal expansion coefficient can be obtained by atmospheric pressure sintering if an air atmosphere is used. Samples NO2 to NO6, N
In O22 to NO27 and NO44 to NO48, the liquid phase is small, and NO18, NO20, NO39, NO41,
In NO60 and NO62, an excessive liquid phase was present.
Therefore, from the above results, the samples NO7 to NO1 in the present invention
7, NO19 and NO28 to NO38 and NO40 and N
In O49, NO59, and NO61, an appropriate liquid phase was formed, and it was found that a dense sintered body having a necessary coefficient of thermal expansion could be obtained by baking at normal pressure in an oxygen atmosphere.
Also, according to Japanese Patent Application Laid-Open No. 52-30162, CaTi
The thermal expansion coefficient of the solid solution of O ₃ and SrTiO ₃ is 30 mol
% CaTiO ₃ and 70 mol% SrTiO ₃ have also been found to be maximal.

Therefore, with respect to the ratio X mol% of the additive P ₂ O _{5 and} the ratio Y mol% of the SiO ₂ , X and Y are the ratios to 100 mol% of the main composition, and the following formula 1 representing the shaded portion in FIG. When 0.5 ≦ X ≦ 40 ≦ Y ≦ 3 Y ≦ −2X + 8 is satisfied, the main composition composed of a solid solution of CaTiO ₃ and SrTiO ₃ and a mixed phase of TiO ₂ has a dense thermal expansion coefficient required. Obviously the body can be made.

[0022]

As is apparent from the above examples, according to the present invention, phosphorus pentoxide (P) is added to the main composition as an additive.
_When the composition contains ₂ O ₅ ) and silicon dioxide (SiO ₂ ), and the mole percent of P ₂ O ₅ is X and the mole percent of SiO ₂ is Y, the following ratio 1.5 ≦ X ≦ 40 <Y ≦ 3 Y ≦ −2X + 8, so that a dense non-magnetic ceramic material for a magnetic head having a necessary coefficient of thermal expansion by a normal pressure firing method, which is advantageous in terms of cost, The manufacturing method can be provided.

[Brief description of the drawings]

FIG. 1 shows the relationship between the ratio of additive SiO ₂ and P ₂ O _{5 in the} nonmagnetic ceramic material for a magnetic head according to one embodiment of the present invention, with the composition 0.6CaTiO ₃ −0.38SrTiO ₃ −0.02.
Diagram showing the main composition of TiO _{2 as} an example

Claims (3)

(57) [Claims] 1. Calcium titanate (CaTiO ₃ ) 1
7 to 60 mol%, strontium titanate (SrTi
O ₃ ) 38-81 mol%, titanium oxide (TiO ₂ ) 0
2 mol% and the total of the three components was 100 mol%, and phosphorus pentoxide (P
_When the composition contains ₂ O ₅ ) and silicon dioxide (SiO ₂ ), and the mole percent of P ₂ O ₅ is X and the mole percent of SiO ₂ is Y, the following ratio 1.5 ≦ X A non-magnetic ceramic material for a magnetic head, characterized by being formed by sintering so as to satisfy ≦ 40 <Y ≦ 3 Y ≦ −2X + 8. 2. The composition raw materials are calcium carbonate (CaCO ₃ ) and strontium carbonate (SrCO ₃ ).
, Titanium oxide (TiO ₂ ) and silicon dioxide (Si
_2. A magnetic head according to claim 1, wherein a composition obtained by calcining a mixture of O ₂ ), phosphorus (P) and oxygen, or a mixture of phosphorus (P), oxygen and hydrogen is used. For manufacturing non-magnetic ceramic materials. 3. The method for producing a non-magnetic ceramic material for a magnetic head according to claim 2, wherein the non-magnetic ceramic material is formed by firing in a normal pressure firing atmosphere and an oxygen atmosphere.