JPH087226A - Non-magnetic substrate for magnetic head - Google Patents

Abstract

PURPOSE:To prevent the deformation of the substrate and peeling of the magnetic film due to the working at the time of manufacturing a magnetic head from occurring and to improve the yield of the magnetic head by using a non magnetic substrate having a high Young's modulus and a thermal expansion coefficient close to that of the magnetic film structure as a component of the head. CONSTITUTION:The magnetic head is provided with this non magnetic substrate for the magnetic head obtained by dispersing an oxide or non-oxide having a higher Young' s modulus than that of a non magnetic oxide which has a rock salt structure comprising CoO and NiO or NiO as its basic composition, into this non-magnetic oxide. The substrate, for example, has a >=220GPa Young's modulus and a >=120XX10<-7>/ deg.C thermal expansion coefficient. The oxide used is at least one oxide selected from BeO, TiO2 and Cabin. and the non-oxide used is selected from B4d, SiC, carbides of elements of groups 4A, 5A and 6A in the periodic Table, Si3N4, AlN and nitrides, borides and silicides of elements of groups 4A, 5A and 6A in the periodic Table. In this substrate, the oxide or non-oxide is dispersed in the non-magnetic oxide in a particulate or whiskery form.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonmagnetic magnetic head substrate for depositing a magnetic film structure.

[0002]

2. Description of the Related Art Conventionally, barium titanate, calcium titanate, alumina, etc. have been used for non-magnetic substrates for magnetic heads of this type. However, since the coefficient of thermal expansion was significantly different from that of the magnetic film structure, the magnetic film structure was easily peeled off, and stress was generated due to the difference in the coefficient of thermal expansion between the magnetic film structure and the substrate, and the substrate was cracked. It happened.

The present inventors have conducted research on oxide-based ceramics in order to solve the above-mentioned drawbacks, and have already disclosed that non-magnetic oxide-based ceramics of rock salt type structure having a basic composition of CoO and NiO or NiO are effective. did. Also, Co
As a method for manufacturing a non-magnetic substrate for a magnetic head having a basic composition of O and NiO or NiO, it has already been disclosed that a manufacturing method including the following steps is effective (Japanese Patent Publication No. 5-29286).
That is, (1) a mixing step of mixing the raw material powders and sieving, (2) a calcination step of calcination of the CIP-molded mixed powder, crushing after crushing, and (3) a calcination powder of 1 μm or less. Step of pulverizing, (4) Step of granulating finely pulverized powder into a sphere of 20 μm or more, (5) Step of CIP-forming granulated powder, (6) Step of sintering a compact, (7) Sintering This is the process of HIPing the body. The non-magnetic substrate produced in this manner is a magnetic film structure, for example, Fe-Si- having a thermal expansion coefficient of about 140 × 10 ^-7 / ° C.
An Al alloy or the like is deposited and processed into a magnetic head.

[0004]

Although the magnetic head is manufactured by processing this sintered body, there is a problem that the substrate is deformed by the processing at the time of manufacturing the head.

[0005]

Therefore, the present inventors have
As a result of studying from the idea that the deformation of the substrate that occurs during head fabrication can be prevented by improving the toughness of the substrate itself, CoO and NiO or NiO is formed into a non-magnetic oxide with a rock-salt structure. , By dispersing an oxide or a non-oxide whose Young's modulus is larger than the non-magnetic oxide,
It has been found that the Young's modulus of the substrate itself is improved and is effective for the deformation of the substrate.

That is, the present invention relates to CoO and NiO or
A non-magnetic substrate for a magnetic head, characterized in that an oxide or non-oxide having a Young's modulus larger than that of a non-magnetic oxide is dispersed in a non-magnetic oxide having a rock salt structure whose basic composition is NiO. The Young's modulus of the magnetic substrate is 220 GPa or more and its thermal expansion coefficient is 120 × 10 ^-7 / ℃ or more. Further, the oxide is at least one selected from BeO, TiO ₂ , and CaTiO ₃ , and the non-oxide is B ₄ C, SiC and Periodic Table 4A,
5A, 6A carbide, Si ₃ N ₄ , AlN and 4A, 5A, 6A nitride, 4A, 5A, 6A boride or silicide non-oxidized A non-magnetic substrate for a magnetic head, wherein the oxide or the non-oxide is dispersed in the form of particles or whiskers.

In order to facilitate understanding of the present invention, the structure of the present invention will be described in detail below. The basic composition is
Means a composite oxide of NiO and CoO, for example, CoO / NiO
(Molar ratio) = 0/100 to 80/20, and more preferably CoO / NiO (molar ratio) = 3/97 to 60, which is close to the thermal expansion coefficient of the magnetic film structure.
/ 40.

As the oxide to be dispersed in the non-magnetic oxide of rock salt type structure having CoO and NiO or NiO as a basic composition, at least one selected from BeO, TiO ₂ and CaTiO ₃ , and as the non-oxide, B ₄ C, SiC and carbides of Group 4A, 5A, 6A of the periodic table, Si ₃ N ₄ , AlN and nitrides of Group 4A, 5A, 6A of the periodic table, boride or silicide of Group 4A, 5A, 6A It is 1 or more types selected from. These oxides or non-oxides are
It is a ceramic material having a large Young's modulus and is a compound that does not form a magnetic compound by reacting with a non-magnetic substrate. The effect of improving Young's modulus can be obtained by dispersing these oxides or non-oxides in the non-magnetic substrate material.

The content of these ceramic materials is such that the Young's modulus is 220 GPa or more and the coefficient of thermal expansion is 120 × 10 ⁻⁷ / ° C. or more. If the Young's modulus is less than 220 GPa, the toughness that can be endured during processing during head production does not appear,
Further, if the thermal expansion coefficient is less than 120 × 10 ^-7 / ℃, because it is significantly different from the magnetic film structure, the magnetic film structure is easy to peel,
Moreover, stress is generated due to the difference in thermal expansion coefficient between the magnetic film structure and the substrate, and cracks are likely to occur on the substrate. Each of the above oxides or non-oxides is used alone as Co
Table 1 shows the content when added to O-NiO (molar ratio; CoO / NiO = 35/65).

[0010]

[Table 1]

Table 1 shows CoO-NiO (molar ratio; CoO / NiO = 35 /
The amount of addition in the case of 65) is shown, but since the additives do not form a solid solution in this system, the thermal expansion coefficient and Young's modulus are
Almost linear with respect to the added amount (volume fraction) of the additive.
Therefore, when using CoO-NiO having different molar ratios, the optimum content of the additive can be determined by converting the values of the coefficient of thermal expansion and Young's modulus of the composition as a base.

Any dispersion form of these ceramic materials may be used, but particles or whiskers are preferable. This is because the use of whiskers changes the propagation form of cracks, so that toughness can be achieved more than when particles are dispersed.

Embodiments of the present invention will be described below.

Example 1 A commercially available TiO ₂ powder was used and the basic composition was CoO / Ni.
O (molar ratio) = 35/65, against which 20vol%, 30vol
%, 40 vol%, and 50 vol% were added to the TiO ₂ powder to prepare mixed powders. The mixing was performed for 20 hours with a wet ball mill using ethanol. This mixed powder was treated in N ₂ gas at 900 ° C. to obtain a calcined powder. The calcined powder was crushed for 40 hours with a wet ball mill using ethanol. After granulating this crushed powder, CIP molding is performed and the molded body is 1500
Hot pressing was performed at 300 ° C. and 300 kg / cm ² . The Young's modulus (GPa) and thermal expansion coefficient (× 10 ^-7 / ° C) by ultrasonic method are shown in Fig. 1. ● is Young's modulus and ○ is thermal expansion coefficient. As a comparative example, CoO / NiO (molar ratio), which was conventionally used, is 35/65.
FIG. 1 also shows the evaluation results of the CoO-NiO substrate similarly prepared with the above basic composition.

From FIG. 1, by adding 25 vol% or more and 40 vol% or less of TiO ₂ , the Young's modulus is improved to 220 GPa or more and the thermal expansion coefficient is also 120 × 10 ⁻⁷ / ° C. or more. In addition, Fe-Si-Al
It was confirmed that the processing yield when the alloy was vapor-deposited and processed into a magnetic head was 50 to 60% in the past, but improved to 70 to 75%.

[0015]

[Example 2] 20vol%, 30vol%, 40vol%, 50vo of Example 1
The properties were evaluated in the same manner except that the 1% TiO ₂ powder was changed to 5 vol%, 20 vol%, and 35 vol% TiC powder. The evaluation result is shown in FIG. From FIG. 2, by adding TiC in an amount of 8 vol% or more and 32 vol% or less, the Young's modulus is improved to 220 GPa or more and the thermal expansion coefficient is 120 × 10 ^-7 / ° C or more. Also, Fe-S
The processing yield when the i-Al alloy was vapor deposited and processed into a magnetic head was 68 to 73%, which was also improved as in Example 1.

[0016]

[Example 3] 20vol%, 30vol%, 40vol%, 50vo of Example 1
The properties were evaluated in the same manner except that the 1% TiO ₂ powder was changed to 5 vol%, 15 vol%, and 25 vol% SiC whiskers. The evaluation result is shown in FIG. From Figure 3, SiC is 8vol% or more 20
By adding less than vol%, the Young's modulus was improved to 220 GPa or more and the thermal expansion coefficient was 120 × 10 ^-7 / ℃ or more. Further, the processing yield when the Fe-Si-Al alloy was vapor-deposited and processed into a magnetic head was 70 to 75%, which was improved as in Example 1.

[0017]

As described above, the non-magnetic substrate according to the present invention has a high Young's modulus and a thermal expansion coefficient close to that of the magnetic film structure. Can be prevented from peeling off, which is advantageous in economic efficiency such as improvement in yield of the magnetic head. In the example, CoO-NiO
Although the non-magnetic oxide is described, the same effect can be obtained in a system in which a compound such as Al ₂ O ₃ is added to CoO—NiO as a sintering aid.

[Brief description of drawings]

FIG. 1 is a diagram showing the dependence of Young's modulus and thermal expansion coefficient on the amount of TiO ₂ added in Example 1 of the present invention.

FIG. 2 is a diagram showing the dependence of Young's modulus and coefficient of thermal expansion on the amount of TiC added in Example 2 of the present invention.

FIG. 3 is a diagram showing the dependence of Young's modulus and thermal expansion coefficient on the amount of SiC added in Example 3 of the present invention.

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Claims (5)

[Claims] 1. A magnetic material characterized by dispersing an oxide or a non-oxide having a Young's modulus higher than the non-magnetic oxide in a non-magnetic oxide of rock salt type structure having a basic composition of CoO and NiO or NiO. Non-magnetic substrate for head. 2. The non-magnetic substrate for the magnetic head has a Young's modulus of 220 GPa or more and a thermal expansion coefficient of 120 × 10 ⁻⁷ / ° C.
The nonmagnetic substrate for a magnetic head according to claim 1, wherein the above is the case. 3. The non-magnetic substrate for a magnetic head according to claim 1, wherein the oxide is at least one selected from BeO, TiO ₂ , and CaTiO ₃ . 4. The non-oxide is B ₄ C, SiC and periodic table 4
A, 5A, 6A carbides, Si ₃ N ₄ , AlN and Periodic Table 4A, 5A, 6A
The non-magnetic substrate for a magnetic head according to claim 1 or 2, wherein the non-magnetic substrate is at least one selected from group III nitrides and borides or silicides of groups 4A, 5A and 6A of the periodic table. 5. The non-magnetic substrate for a magnetic head according to claim 1, claim 2, claim 3 or claim 4, wherein the oxide or non-oxide is dispersed in the form of particles or whiskers.