JPH0649608B2 - Non-magnetic material for thin film magnetic head substrate and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a Zn ferrite for a thin film magnetic head substrate, which includes an additive element of potassium oxide or sodium oxide,
The present invention relates to a Zn ferrite having uniform fine crystals, being non-porous and having excellent workability.

Background Art Since a thin film magnetic head substrate is generally subjected to precision processing, it is required to have excellent workability without chipping, to have few holes, and to be made of uniform fine crystals and have good compatibility with the medium. Has been done.

Conventionally, glass and silica-based
Non-magnetic materials such as alumina have been put to practical use.

In addition, the applicant has excellent characteristics as a substrate for a thin film magnetic head, but with regard to Ni-Zn ferrite which has not been put into practical use because micropores are generated on the processed surface, the generation of micropores on the processed surface is prevented. Proposed the ferrite (JP-A-61-1)
No. 11512).

Further, as Zn-ferrite, ZnO 46 to 52 mol%, Fe ₂ O
_A composition of ₃ 48 to 54 mol% is known,
The Zn ferrite may cause chipping when the rail is processed into a magnetic head shape, resulting in a reduction in product yield.

It is an object of the present invention to eliminate the drawbacks of the conventional Zn ferrite for thin film magnetic head substrates, to be formed of uniform fine crystals with few holes, and to be used for thin film magnetic head substrates with excellent precision workability.
The purpose is to provide ferrite.

SUMMARY OF THE INVENTION The present invention contains one or two kinds of K ₂ O and Na ₂ O in 0.005 to 0.1 wt% in a basic composition of 46 to 52 mol% of ZnO and 48 to 54 mol% of Fe ₂ O ₃ , It is a non-magnetic material for a thin film magnetic head substrate, which has a porosity of 0.05% or less and an average crystal grain size of 10 μm or less.

In addition, the present invention provides a basic composition consisting of 46 to 52 mol% ZnO and 48 to 54 mol% Fe ₂ O _{3 in} a composition containing 0.005 to 0.1 wt% of one or two of K ₂ O and Na ₂ O. As described above, the raw material powders are mixed and mixed, or the coprecipitated raw material is molded, and the compact is pre-sintered at 1000 ° C to 1300 ° C to have a density of 95% or more of the theoretical density and an average crystal grain size of 10 μm or less. After that, the sintered body is hot isostatically pressed at a temperature of 900 ° C to 1300 ° C and a pressure of 600 kg / cm ^{2 to} 2000 kg / cm ² for 1 to 5 hours, so that the porosity of the product is 0.05 %, And the average crystal grain size is 10 μm or less, a non-magnetic material for a thin film magnetic head substrate can be obtained.

EFFECTS OF THE INVENTION The present invention relates to Zn ferrite containing a specific amount of K ₂ O and Na ₂
Characterized by containing one or two kinds of O, the product has few pores, and the crystal grain size is fine and uniform.
It does not cause chipping during precision processing, has excellent workability, and is well compatible with recording media.

Structure of the Invention In the present invention, the basic composition is ZnO 46-52 mol%, Fe ₂
Outside the composition range of O ₃ 48 to 54 mol%, sufficient sinterability cannot be obtained and the crystal grain size becomes nonuniform, which is not practical as a thin film magnetic head substrate.

In the present invention, one or two of K ₂ O and Na ₂ O is 0.0
If it is less than 05 wt%, the effect is not sufficient, and if it exceeds 0.1 wt%, the sinterability decreases, the crystal grain size becomes non-uniform, a dense sintered body cannot be obtained, and the workability also deteriorates. Is not preferred.

In the present invention, the porosity of the product Zn ferrite is 0.05
%, The reason for limiting the average crystal grain size to 10 μm or less is
If the porosity exceeds 0.05% and the average crystal grain size exceeds 10 μm, chipping tends to occur when grooving this ferrite material into the required magnetic head shape, and it cannot be processed into a predetermined shape. Further, the magnetic film may peel off during processing, which is not preferable.

In the pre-sintering conditions of the present invention, if the sintering temperature is less than 1000 ° C, a dense sintered body cannot be obtained, and if it exceeds 1300 ° C, the crystal grain size of the sintered body becomes non-uniform and the hot static After the hydraulic press treatment, the precision workability is deteriorated, which is not preferable.

If the pre-sintering time is less than 1 hour, a dense sintered body cannot be obtained, and if the pre-sintering time exceeds 5 hours, the crystal grain size of the sintered body becomes nonuniform, and even after hot isostatic pressing. Since there are no pores and a dense product with a uniform crystal grain size cannot be obtained, a product with excellent workability cannot be obtained.

In addition, hot isostatic press treatment conditions are temperature 900 ℃ ~ 1300
° C., at a pressure ^{600kg / cm 2 ~2000kg / cm 2} , except the conditions of retention time of 1 hour to 5 hours, the porosity of 0.05% or less, the average crystal grain size is less 10μm dense and excellent precision processability It is impossible to obtain Zn ferrite.

In the present invention, oxides may be used as raw materials, but carbonates, hydroxides, oxalates and the like obtained by decomposition of these oxides can be used.

Examples Fe ₂ O ₃ , ZnO as raw materials and K ₂ O, Na ₂ O as additives
Were blended as shown in Table 1, thoroughly mixed in a ball mill, and then calcined at 1000 ° C. in the atmosphere.

Further, it was crushed with a ball mill to have a particle size of 2.0 μm or less.

After adding a binder to this raw material powder and granulating, 40 mm x 40
It was molded into a lump having a size of mm, and the molded body was presintered at 1250 ° C. for 1 hour to obtain a sintered body having a sinterable average crystal grain size as shown in Table 1.

Next, this sintered body was treated with a hot isostatic press under the conditions of a holding temperature of 1200 ° C., a holding time of 2 hours, and a pressure of 1000 kg / cm ² .

Porosity, average particle size, of hot isostatic pressed test pieces
Table 1 shows the presence / absence of chipping having a size of 5 μm or more generated in the test piece when cut and processed using a cutting machine.

Claims (2)

[Claims] 1. A basic composition comprising 46 to 52 mol% of ZnO and 48 to 54 mol% of Fe ₂ O ₃ and 0.005 of one or two of K ₂ O and Na ₂ O.
~ 0.1wt% content, porosity 0.05% or less, average crystal grain size 10
A non-magnetic material for a thin-film magnetic head substrate, which has a thickness of μm or less. 2. A basic composition comprising 46 to 52 mol% of ZnO and 48 to 54 mol% of Fe ₂ O ₃ and 0.005 of one or two of K ₂ O and Na ₂ O.
The molded product blended to obtain a composition containing ~ 0.1wt% is pre-sintered at 1000 ℃ ~ 1300 ℃,
After the average crystal grain size is 95% or more and the average crystal grain size is 10 μm or less, the sintered body is subjected to hot isostatic pressing to obtain a porosity of 0.05% or less,
A method for producing a non-magnetic material for a thin-film magnetic head substrate, characterized in that a product having an average crystal grain size of 10 μm or less is obtained.