JPH01252565A - Non-magnetic porcelain material for magnetic head and production thereof - Google Patents

Abstract

PURPOSE:To provide the title material of high thermal expansion coefficient, outstanding in wear resistance, smooth, few in voids, suitable as a slider for magnetic head, comprising BaO, TiO2 and NiO in specified proportion. CONSTITUTION:The objective porcelain material >=120X10<-7>/ deg.C in thermal expansion coefficient, comprising (A) 0.8-8mol% of BaO, (B) 6-33mol% of TiO2 and (C) the rest of virtually NiO. Said material is pref. further incorporated with, as subcomponent(s), 0-10wt.% (except 0) of at least one kind of substance selected from Al2O3, SiO2, MgO, SnO, ZrO2, Nb2O5, MnO and ZnO. Said material can be obtained by the following process: the first raw material containing BaO and TiO2 are mixed, ground and preliminarily calcined at 800-1200 deg.C. The resultant mixture is mixed with the second raw material incorporated with NiO followed by grinding the resultant mixture to produce the second mixture, which is then put to hydraulic press forming and sintering at 1200-1300 deg.C.

Description

[Detailed Description of the Invention] [Industrial Application Field] This field relates to non-magnetic ceramic materials for magnetic heads conventionally used in floppy disk heads, hard disk heads, audio heads, etc. and methods for manufacturing the same, and in particular to slider materials and methods for manufacturing the same. It is.

[Prior Art] Conventionally, MaO-T101 series and Ca0-T are used as non-magnetic ceramic materials for magnetic heads used in floppy disk heads, hard disk heads, audio heads, etc.
Titania-based porcelain, mainly iO□-based, has been used. The common property of these porcelains is that their Vikers hardness is 7.
It has a hardness close to that of ferrite at Q/mn' of 00 to 900, and its sintered body is dense and a smooth polished surface can be obtained. In addition, by adjusting the chemical composition, the thermal expansion coefficient can be changed from 90 x 10-7/℃ to 97xl□-7 (B
a OT i O2 system), 90 x 10-7/°C ~ 11
7 X 10-7/”C (Cao Ti 02 series)
and can be adjusted freely. Vikers hardness represents the wear resistance of the material, and the above values are for N1-Zn ferrite and Mn-
Since the tensile strength is relatively similar to that of Zn ferrite, it satisfies the conditions required for a slider material.

In addition, a smooth polished surface is a basic condition for the structure of a magnetic head that constantly slides in contact with a magnetic recording medium to reduce friction with the recording medium and prevent scratches on the recording medium.

Furthermore, adjustment of the coefficient of thermal expansion prevents cracks that occur in the core due to thermal stress caused by the difference in coefficient of thermal expansion when joining the core material of the magnetic head with glass bonding, and prevents deterioration of magnetic properties and operation due to residual stress. This is necessary to prevent the occurrence of thermal stress due to temperature changes over time and the accompanying performance deterioration of the magnetic head.

In this way, Bad-Ti12 system and Ca0-T i O
In order to satisfy the basic requirements for slider materials for magnetic heads, most of the slider materials for magnetic heads are currently made of BaO-TiO2-based or CaOTiO-based porcelain materials. be.

[Problem to be solved by the invention] However, as the magnetic recording density (B) increases year by year, the ferrite used as the core material of the magnetic head is required to have as large a magnetic flux density B as possible in its design. . In particular, in order to obtain a high magnetic flux density B in the Mn-Zn ferrite system, it is necessary to adjust the composition ratio. -7/℃
Mn- for magnetic heads such as ~145X10-7/'C
Zn ferrite is obtained and has such a high coefficient of thermal expansion. Mn-Zn ferrite came into use. For this reason, the conventionally used B a OT L 02
Even if the composition is adjusted, the coefficient of thermal expansion of CaOTiOf type and CaOTiOf type ceramic materials is at most about 117X10-'~/℃, so when using these conventional slider materials for a ferrite core that has achieved a high magnetic flux density, However, due to the mismatch in thermal expansion coefficients between the two, the core cracked during the manufacturing process and the performance of the magnetic head deteriorated.

Therefore, the technical problem of the present invention is to adjust the chemical composition of BaoTiOx-NiO-based porcelain material in order to eliminate these drawbacks, and to
It has achieved a thermal expansion coefficient of 120X10-7/℃ or higher, which was impossible with CaOTiO2-based porcelain. It is an object of the present invention to provide a smooth non-magnetic ceramic material for a magnetic head with few voids and a method for manufacturing the same.

[Means for Solving the Problems] According to the present invention, BaO is 0.8 to 8 mol%, TiO2 is 6 to 33 mol%, and the balance is substantially N.
Contains a main component consisting of iO and has a thermal expansion coefficient of 120X1
A non-magnetic ceramic material for a magnetic head, which is characterized by a temperature of 0-7/°C or higher, is obtained.

Further, according to the present invention, in addition to the main components described above, Aj, O, SiO□, and MgO are added as subcomponents.

At least one selected from SnO, ZrO2, NbtOs, MnO, ZnO in a weight percentage of 0 to 10
A non-magnetic ceramic material for a magnetic head is obtained, which is characterized in that it contains wt% (0 is included).

Further, according to the present invention, a first raw material containing BaO and T i O2 is mixed and pulverized to obtain a first mixture.
A pre-firing step of pre-firing a mixture of a second mixing step to obtain a molded product, a compression molding step to obtain a molded product by hydraulic press molding the second mixture, and a compression molding step to obtain a molded product at 1000°C to
A method for manufacturing a non-magnetic ceramic material for a magnetic head is obtained, which comprises a firing step of firing at a temperature within a range of 1300°C.

Furthermore, according to the present invention, there is obtained a method for manufacturing a non-magnetic ceramic material for a magnetic head, which comprises a hot pressing step of hot pressing the fired compact after the above-described firing step.

Here, the second mixture is AI 20B.

5iOz, MgO, SnO, ZrO2°N b 20
It is desirable to contain at least one selected from s, MnO, and ZnO in a weight percentage of 0 to 10 wt% (excluding 0), which is Bad.

The molar ratio of TiO2 and NiO components is 0°8~
8 mol%, preferably 6 to 33 mol%.

[Function] Next, the function of the present invention will be explained below with reference to the drawings. FIG. 1 shows a magnetic microstructure having a plurality of crystal phases. In this figure, the shaded crystal phases are referred to as A layer, and those without diagonal lines are referred to as B layer.

Now let the thermal expansion coefficient of the A layer be αa, and the thermal expansion coefficient of the B phase be α8, and the volume ratios occupied by each of them per a certain volume are λ, λ
Then, the coefficient of thermal expansion α of a substance consisting of a mixture of two phases is (
It can be estimated using equation 1).

α=λ, α, +λ−αb (1) Therefore, if the thermal expansion coefficient of the desired porcelain material is between α and αゎ, adjust the mixing ratio of the two phases to λ.

By adjusting λ to an appropriate value, the required α can be achieved. However, in this case, a new reaction product is created between the two crystalline phases that are mixed, and the coefficient of thermal expansion of this material is α, α
When the value is far from b, the relationship in equation (1) does not hold.

Figure 2 shows the relationship between the mol% of T i O2 and the thermal expansion coefficient of BaO-TiO2-based porcelain.
It is observed that the coefficient of thermal expansion decreases monotonically as O2 becomes larger than BaO. Around this chemical composition, B
a2Ti*Ot. phase and T i O2 phase are mixed, B
Depending on the combination of aO and T i O2, structures with different proportions of both phases can be obtained.

Therefore, the thermal expansion coefficient of the B a OT i Oi system is B
It is determined by the relationship of equation (1) based on the thermal expansion coefficient of the a2T i 902G phase and the thermal expansion coefficient of the TiO2 phase.

Based on the principle of equation (1), the coefficient of thermal expansion is 120X 1
In order to obtain a porcelain material of 0-7/'C or higher, α must be 12
This can be achieved by dispersing a substance of 0x10-7/'C or higher into the fine structure. For this purpose, it is necessary to make the thermal expansion coefficient as large as possible and to have good compatibility when the main component Ba0-T i O is mixed with the system.
It is necessary to select a third material that does not lose the characteristics of the system, such as a smooth polished surface, appropriate hardness, good workability, and nonmagnetism.

The present invention was developed as a result of studying various substances for this purpose (
B a mixed with NiO (nickel oxide) as the third component
o T i 02 B i O-based porcelain meets all the basically necessary conditions as a non-magnetic material for a magnetic head, and has a desired thermal expansion coefficient of 120 to 140.
It was discovered that the temperature could be adjusted between X-7/°C.

Furthermore, AJ20m is added to the main component as a subcomponent.

5in2. MgO, SnO, ZrO2+NbzOs
, MnO, and ZnO.
It was discovered that by suppressing the growth of crystal grain sizes of the O2O phase, 'rtot phase, and MnO phase and reducing the porosity, the mechanical strength of magnetic materials can be improved and chipping resistance during processing can be improved. .

What should be added further is that B a OT i O2−NiO
This type of porcelain material basically exhibits a dark green to black color, and does not undergo coloration due to reduction during the hot isostatic pressing (HIP) process, which is extremely common in the production of non-magnetic materials for magnetic heads today, and the color remains unchanged on the production line. This has the advantage of not causing instability.

[Example] Examples of the present invention will be described below.

Table 1 shows the basic characteristics of nonmagnetic materials for magnetic heads according to examples of the present invention.

Margin below In this table, porcelain materials containing Bad, TiOz, and NiO as the balance of 1 to 10% and 5 to 40%, respectively
Sintered density of l~k10, coefficient of thermal expansion, Vikers hardness,
The bending temperature is investigated.

The density of the sintered body shows a tendency to increase as NiO increases.

Furthermore, in the Ba0-TiOz-NiO system, conventional B10
-Thermal expansion coefficient 12 that could not be achieved in the Ti0□ system
0x10-7/°C or higher was achieved as predicted, and at the same time, the basic mechanical properties such as Vikers hardness, bending strength, and workability are close to those of the conventional Ba0-T i Ox system, and this system can be used as a non-magnetic material for magnetic heads. was found to have basically sufficient characteristics.

For materials containing 60 mol % or less of NiO, the coefficient of thermal expansion is equal to the upper limit of the conventional CaOTiO2 system.

On the other hand, if the NiO content is 92 mol% or more, the Vikers hardness decreases and wear resistance and mechanical strength are poor.

In the molar ratio of BaO and T i O2, T i O2/
When BaO is less than 3, a B a T i 40 * phase is likely to occur, resulting in a decrease in mechanical strength (fourth material).

At the same time, when TiO2/BaO becomes larger than 5, the thermal expansion coefficient of the crystalline phase composed of BaOTiO2 in the microstructure decreases below 90X10-'/''C as the T192 phase increases and decreases to the overall value in equation (1). (fifth material).

As a result, it was found that if the mol% of BaO in the whole is in the range of 0.8 to 8 mol% and the TiO2 content is in the range of 6 to 33 mol%, the material has excellent mechanical strength and a good coefficient of thermal expansion.

As a result of the above, the optimum basic configuration in the embodiment of the present invention is the range surrounded by the solid line 1, as shown in FIG.

Titanium dioxide barium carbonate with a purity of 97% or more, which is a commercially available reagent, was weighed as a raw material to give a predetermined chemical composition, and mixed in a resin ball mill, high-strength zirconia balls, and pure water for more than 20 hours.

Next, after filtering and drying, put it in an alumina sagger and heat it to 800℃~120℃.
Prebaking was performed at 0°C for 2 hours or more.

Next, using a resin ball mill, BaO-TiO2-based prefired powder and a predetermined amount of nickel oxide were weighed and mixed and wet-pulverized at the same time using high-strength zirconia balls and pure water for over 20 hours.

- After over-drying, mix 8% PVA solution with 10wt% Laikaiki, pass through a 28-mesh sieve, adjust the moisture content, and press with a hydraulic press at a pressure of 1 ton/aa to form 4 squares, 50 sides horizontally, and 10 squares high. I got a body. Subsequently, this compact was fired in the atmosphere at 1200 to 1300° C. for 2 hours or more to obtain a porcelain material.

(1st to 10th porcelain materials) Example 2゜ Example 2 of the present invention will be described.

Table 2 shows the basic characteristics of the magnetic head material according to Example 2 of the present invention.

Margin below: In this table, nonmagnetic material for magnetic head NQ3 obtained in Example 1. Nc6. Regarding NO3, HIP uplink is applied.

It was found that the coefficient of thermal expansion was the same as that of the material according to Example 1, while the sintered density, Vikers hardness, and bending strength were all increased.

A magnetic head material according to Example 2 of the present invention was manufactured as follows. No. 3 obtained in Example 1. The sixth and eighth materials were heated to 110° C. using a hot isostatic pressing (HIP) device.
HIP treatment was performed at 0° C. to 1300° C. under a pressure of 1000 kg/cd for − hours to 3 hours, and the 3′ and 6′
, a non-magnetic material for the 8th magnetic field was obtained.

Table 2 shows measurements made on the 3', 6', and 8' nonmagnetic materials.

Example 3゜ Example 2 of the present invention will be described.

Table 3 shows the basic characteristics of the magnetic head material according to Example 3 of the present invention, in which the non-magnetic material of Example 1 is the main component, additives are added in the mixing stage, and the manufacturing process of Example 1 is followed. The basic physical properties of the obtained 11th to 43rd materials were measured.

Margin below As is clear from this table, AjliOs.

5iOz, MgO, SnO, ZnO, Y20s.

It has been confirmed that by adding an appropriate amount of either Nbx Os or MnO, the average particle size can be made finer and transverse rupture strength and Vikers hardness can be improved.

Furthermore, it was confirmed that chipping during processing can be significantly suppressed by adding an appropriate amount. Furthermore, it has been found that for any of the above-mentioned additives, if the amount added exceeds 5 to 10 wt%, chipping tends to occur during processing, resulting in brittleness.

Therefore, in addition to Example 3 and the above main components, Aj20s
, S i O2, MgO, SnO, ZnO.

At least one selected from Nb2O3 and MnO
It has been found that adding 0 wt% or less can improve strength and suppress chipping.

[Effects of the Invention] As detailed above, according to the present invention, the conventional Bad-T can be used for ferrite with high magnetic flux density required for high-density recording.
A magnetic head magnetic material with a thermal expansion coefficient of 120xlO-7/'C or more, which could not be achieved with the i12 series and Cab-Ti12 series, and its I! ! This is extremely useful industrially.

[Brief explanation of the drawing]

Figure 1 shows a model of the microstructure of a non-magnetic ceramic material consisting of multiple crystal phases, and Figure 2 shows the relationship between the molar ratio of BaO and TiO□ and the coefficient of thermal expansion in a Ba0-TiO system. It is a diagram. FIG. 3 is a diagram showing the chemical composition of a nonmagnetic ceramic material for a magnetic head according to an embodiment of the present invention.

Claims (4)

[Claims] 1. BaO in molar percentage is 0.8-8 mol%, TiO_
1. A nonmagnetic ceramic material for a magnetic head, characterized in that the main component is 6 to 33 mol% of NiO2 and the remainder is substantially NiO, and has a coefficient of thermal expansion of 120 x 10^-^7/°C or more. 2. In addition to the above main components, Al_2O_3 and Si are added as subcomponents.
O_2, MgO, SnO, ZrO_2, Nb_2O_3
, MnO, and ZnO,
The non-magnetic ceramic material for a magnetic head according to claim 1, characterized in that it contains 0 to 10 wt% (excluding 0). 3. A first mixing step of mixing and pulverizing a first raw material containing BaO and TiO_2 to obtain a first mixture, and pre-firing the first mixture at a temperature within the range of 800°C to 1200°C. a pre-firing step; a second mixing step of mixing and pulverizing a second raw material containing NiO into the pre-baked first mixture to obtain a second mixture; and hydraulic press molding of the second mixture. A method for manufacturing a non-magnetic ceramic material for a magnetic head, comprising: a compression molding step for obtaining a molded body; and a firing step for firing the molded body at a temperature within a range of 1200 to 1300°C. 4. 4. The method of manufacturing a nonmagnetic ceramic material for a magnetic head according to claim 3, further comprising a hot pressing step of hot pressing the fired compact after the firing step.