JPH059056A - Ceramic head for magnetic head - Google Patents

Abstract

(57) [Summary] [Structure] MgO, MgCO ₃ , Al ₂ O ₃ , CaO, CaCO is added to the main composition of Na ₂ O and Nb ₂ O _5.
A ceramic substrate for a magnetic head is obtained by firing a porcelain composition containing at least any one of _{3 above} . [Effect] It is possible to obtain a ceramic substrate for a magnetic head which has an appropriate linear thermal expansion coefficient and Vickers hardness, a small grain size, and excellent workability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic substrate for a magnetic head used as a slider for a composite head or the like.

[0002]

2. Description of the Related Art For example, in a magnetic head for recording / reproducing on / from a magnetic disk such as a hard disk or a floppy disk, a ceramic substrate is provided around the magnetic core in order to secure a hitting property against the disk and protect the magnetic core. It is generally a so-called composite head structure surrounded by.

The ceramic substrate provided around the magnetic core is usually bonded to the magnetic core by glass fusion. Therefore, if the coefficient of linear thermal expansion of the ceramic substrate and the coefficient of linear thermal expansion of the magnetic core are significantly different, stress is generated between the magnetic core and the ceramic substrate due to the heat during the glass fusion, and the ceramic substrate is peeled off. Cause trouble. For this reason, the ceramic substrate is required to have excellent contact characteristics with respect to the disk and to have a linear thermal expansion coefficient similar to that of the magnetic core in order to prevent the above-mentioned trouble.

Conventionally, such a ceramic substrate has a linear thermal expansion coefficient of 110 × 10 from room temperature to 400 ° C.
^A ceramic substrate made of CaTiO ₃ (calcium titanate) at about ⁻⁷ / ° C. is used. However, this linear thermal expansion coefficient is low with respect to the linear thermal expansion coefficient of the metallic magnetic material or Mn—Zn ferrite used as the magnetic core material for the magnetic disk, and stress is generated during glass fusion. Can not be joined sufficiently. Moreover, since calcium titanate has a high Vickers hardness of about 900,
It also has the drawback of being difficult to cut.

A ceramic substrate made of NaNbO ₃ (sodium niobate) is known as a ceramic substrate for solving the above problems. This sodium niobate has a large coefficient of linear thermal expansion of 120 to 130 × 10 ⁻⁷ / ° C., has good bondability to a core material such as Mn—Zn ferrite, and has a Vickers hardness of about 700. Therefore, the cutting process is easier than that of the ceramic substrate made of calcium titanate.

[0006]

However, a ceramic substrate made of sodium niobate has a problem that chipping is likely to occur during microfabrication because the grains grow large during firing, which makes precise machining difficult. In that respect, it is not completely satisfactory.

Therefore, the present invention has been proposed in view of such a conventional situation, and the linear thermal expansion coefficient is Mn−.
A ceramic substrate for a magnetic head, which is about the same as a core material such as a Zn-based ferrite, has good bondability to a magnetic core, has proper Vickers hardness and grain size, and has excellent workability. The purpose is to provide.

[0008]

[Means for Solving the Problems] Sodium niobate is
The linear thermal expansion coefficient is close to the linear thermal expansion coefficient of Mn—Zn-based ferrite or the like, which is the core material, and the Vickers hardness is also an appropriate value, so that it is suitable as a material for the ceramic substrate for the magnetic head. However, since the grain size is large, chipping is likely to occur during processing, and there is a drawback that fine processing is difficult.

As a result of intensive studies by the present inventors in order to eliminate such drawbacks of sodium niobate, when a sintered body is obtained, a main composition of Na ₂ O and Nb ₂ O _{5 is} added to MgO. , MgCO ₃ , Al ₂ O ₃ , CaO, Ca
It has been found that the grain size can be reduced by adding any one of CO ₃ .

The ceramic substrate for magnetic head of the present invention is
It was proposed based on such knowledge, and
_With respect to 100 parts by weight of the main composition composed of ₂ O and Nb ₂ O ₅ , MgO, MgCO ₃ , Al ₂ O ₃ , CaO, CaC
The ceramic composition is obtained by adding 0.5 to 5.0 parts by weight of at least one of O ₃ and firing.

The ceramic substrate for a magnetic head of the present invention is
It is formed by firing a ceramic composition containing Na ₂ O and Nb ₂ O ₅ as main compositions. This Na ₂ O, Nb ₂ O ₅
In order to make the linear thermal expansion coefficient and the Vickers hardness appropriate, the amount ratio of Na ₂ O is a mol, Nb ₂ O
_When the amount of ₅ is b mol, a / b is 0.7 to 1.0
Is preferred.

In the above-mentioned magnetic head ceramic substrate, MgO, MgCO ₃ , Al ₂ O ₃ , CaO, CaC is added to the main composition in order to refine the grains of the sintered body.
At least one kind of O ₃ is added.

In order to achieve the above effects and maintain the linear thermal expansion coefficient and Vickers hardness at appropriate values, the amount of these additives added is 100 parts by weight of the main composition.
It is necessary to be 0.5 to 5.0 parts by weight. When the amount of the above compound added is 0.5 parts by weight or less, the grain refining effect is not sufficiently obtained, and chipping occurs during processing. On the other hand, when the above-mentioned additive is added in excess of 5.0 parts by weight, the sintering density, the coefficient of linear thermal expansion, and the Vickers hardness deviate from appropriate values, and the characteristics of the head ceramic substrate deteriorate. For example, MgO or Al ₂
If O ₃ is added in an amount of more than 5.0 parts by weight, the sinterability deteriorates, the sintered density decreases, and the Vickers hardness and linear thermal expansion coefficient also decrease. On the other hand, when CaCO ₃ exceeds 5.0 parts by weight, the linear thermal expansion coefficient becomes too large and becomes weak against thermal shock.

The ceramic substrate is manufactured by the usual ceramic manufacturing process except that the above-mentioned additional elements are added. Here, above the addition of the additive elements, after preliminary firing a mixture of Na ₂ O and Nb ₂ O _5, may be added to the calcined powder, Na ₂ O and Nb ₂
In mixing the O _5, it may be added simultaneously. At this time, the same effect can be obtained even if two or more of the above-mentioned additional elements are added in combination.

[0015]

[Function] In the main composition consisting of Na ₂ O and Nb ₂ O ₅ ,
MgO, MgCO ₃ , Al ₂ O ₃ , CaO, CaCO ₃
When a predetermined amount of at least one of the above is added and fired, a fine sintered body having a grain size is obtained. This sintered body has a fine grain size and a linear thermal expansion coefficient close to that of a core material such as Mn-Zn ferrite, and Vickers hardness is also suitable for processing. There is. Therefore, when cutting is performed, chipping is unlikely to occur, fine processing is performed accurately, and when bonded to a Mn—Zn-based ferrite core material, stress due to thermal expansion hardly occurs, and good bondability is obtained. Be done.

[0016]

EXAMPLES Preferred examples of the present invention will be described based on experimental results. In this example, Na ₂ CO ₃ and Nb ₂
When obtaining a sintered body containing O ₅ as a main component, MgO, Al
₂ O ₃ and CaCO ₃ were added in various amounts, and the effect of the addition of these additives on the properties of the sintered body was examined.

First, 0.9 mol of Na ₂ CO ₃ and Nb ₂ O
After mixing 1 mol of ₅ mol with a wet ball meal using ethanol as a medium, the medium was removed. Then, this mixture is calcined in an oxidizing atmosphere at 900 ° C. for 4 hours, and MgO, Al ₂ O ₃ and CaCO ₃ are added to the calcined powder as additives.
Was added in the ratio shown in Table 1 and Table 2. Next, ethanol is used as a liquid medium and mixed again with a wet ball mill to remove the liquid medium, and then a 10% aqueous solution of PVA (polyvinyl alcohol) is added as a binder for granulation, and the molding pressure is 1 t.
It was press-molded at on / cm ² . Then, this molded body was fired in an oxidizing atmosphere at 1200 ° C. for 4 hours to manufacture various sintered bodies (sintered body 1 to sintered body 20).

The coefficient of linear thermal expansion, the Vickers hardness, and the grain size of each sintered body thus obtained were measured in an oxidizing atmosphere. The results are shown in Tables 1 and 2. In addition, in order to evaluate the workability, each of the above-mentioned sintered bodies was mirror-finished, and then grooving was performed with a diamond grindstone, and the occurrence of chipping that occurred at that time was observed. The results are also shown in Tables 1 and 2. In Tables 1 and 2, the occurrence of chipping was expressed as “Yes” when chipping of 1 μm or more was observed and “No” when chipping of 1 μm or more was not observed.

[0019]

[Table 1]

[0020]

[Table 2]

As is clear from Tables 1 and 2, in the sintered body 1 to which no additives are added, the grain size is large and chipping occurs during processing. On the other hand, in the sintered bodies 2 to 20 in which 0.5 parts by weight or more of at least one of MgO, Al ₂ O ₃ and CaCO ₃ is added, the grain size is small,
Almost no chipping was observed during processing. From this, when a predetermined additive is added in obtaining a sintered body containing sodium niobate as a main component, the grains become finer, and the obtained sintered body becomes a ceramic substrate having good workability. all right.

However, the sintered bodies 5, 9, 13, 15, 1
As can be seen from Nos. 7 and 19, the addition amount of the above-mentioned additive is 5
If it exceeds the parts by weight, the sintered density will decrease and the Vickers hardness,
The linear thermal expansion coefficient also deviates from the value of the sintered body 1 and does not show an appropriate value.

Therefore, in order to make a ceramic substrate for a magnetic head excellent in all characteristics,
It has been found that the addition amount of the above additive is preferably 0.5 to 5.0 parts by weight.

[0024]

As is apparent from the above description, the ceramic substrate for a magnetic head according to the present invention is Na ₂ O and Nb.
_The ceramic composition for a magnetic head has a thermal expansion coefficient, Vickers hardness, and grain size because it is a sintered body obtained by firing a porcelain composition obtained by adding an appropriate amount of a predetermined compound to a main composition of ₂ O _5. Has become appropriate. Therefore, it is possible to perform precision processing applied to a ceramic substrate, and when bonded to a magnetic disk core material such as Mn-Zn ferrite, stress due to thermal expansion hardly occurs and good bondability can be obtained. it can.

Claims (1)

Claims: 1. MgO, MgCO ₃ , Al ₂ O based on 100 parts by weight of the main composition consisting of Na ₂ O and Nb ₂ O _5.
A ceramic substrate for a magnetic head obtained by firing a porcelain composition obtained by adding 0.5 to 5.0 parts by weight of at least any one of ₃ , CaO and CaCO ₃ .