JPS6013787B2 - Precision polishing method for polycrystalline ferrite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precision polishing method for processing the surface of a polycrystalline ferrite material into a precision flat surface.

Permalloy, ferrite, sendust, etc. are used as materials for magnetic heads, and each has its own characteristics in terms of magnetic properties, wear resistance, precision machinability, etc., and they are used depending on the recording wavelength, relationship with the media, and purpose of the magnetic head. There is.

Further, magnetic heads for audio, video, computer, etc. are required to have improved magnetic recording density, and for this reason, magnetic heads manufactured using IC technology are considered optimal.

For example, ferrite is more suitable than metal for a substrate for a thin film head, and it is considered most effective to use polycrystalline ferrite, which is cheaper than single crystal.

Such a board is plated with magnetic materials and non-magnetic materials constituting a magnetic circuit or L elements for detecting magnetic fields on the slope.
Since it is formed by vapor deposition, sputtering, etc., distortion-free processing is required to improve the smoothness of the substrate surface and the magnetic properties of the ferrite magnetic substrate. Until now, mechanical polishing using diamond as an abrasive has been frequently used as a polishing method.

Furthermore, mechanochemical polishing method enables chemical strain relief processing, and mechanochemical polishing using fine powder of Si02 has been applied to polishing single crystal materials.
However, in the case of polycrystalline materials, the chemical erosion rate naturally differs depending on the crystal orientation, so it is difficult to apply this mechanochemical polishing, and it is thought that crystal steps will always occur under normal processing conditions, which does not meet the purpose. It will be done.

Furthermore, in order to obtain ultra-precise flat surfaces of polycrystalline materials with high efficiency, the properties of the powder, etc. are further limited. This invention proposes a precision polishing method for processing a polycrystalline ferrite material into a precision plane.

That is, the present invention is a polishing method using MgO powder, which is generally considered to be unsuitable due to the occurrence of large crystal steps in such mechanochemical polishing. A precision flat surface can be obtained by polishing a polycrystalline ferrite material using a solution in which fine powder is suspended in pure water and has a viscosity of 20 p or less. To explain in detail, a polisher made of a predetermined material is configured to be rotatable in a suspension of Mg○ fine powder in pure water, and a rotating member holding the material to be polished on the surface of the polisher is applied with a predetermined load to polish the polisher. Provide materials,
These are rotated and polished in a liquid.

By this method, a polycrystalline ferrite material can be processed into a precision flat surface, and the polisher material, its rotation speed, etc. may be appropriately selected.

Here, if a suspension of Mg○ fine powder in pure water is used in an alkaline region, processing efficiency will be improved.

In addition, the amount of Mgq-like powder is suspended in pure water, and the amount is 0.5-2.
Machining efficiency is improved by setting the mol% and ol%. Furthermore, we found that the viscosity of this suspension in pure water significantly changes the processability.

That is, it is thought that when the viscosity of the suspension increases, the mutual interaction between fine powders becomes stronger, the reaction with ferrite becomes slower, and processing phenomena no longer occur. Therefore, the viscosity measured with a B-type viscometer is 20
By setting p to less than p, workability is improved, and the surface of the polished material becomes an extremely fine precision flat surface.

That is, 65 g of Mg○ fine powder was suspended in pure water per night, and the viscosity was adjusted to 20 p or less as measured with a B-type viscometer. Mg○ fine powder contains Pb, Fe,
Although the initial viscosity differs due to impurities such as Ca, Na, CI, S04, etc. and the loss of carbonate radicals on ignition, Mg
The chemical reaction to (OH)2 is promoted and hydration occurs, and there is a tendency for gelation to occur. Therefore, during the production of Mg○ fine powder, the viscosity is kept below 20p by adjusting the total amount of impurities to 0.0 to 2.0% or by adjusting the ignition loss to io to 18%. can do.

In addition, if the viscosity of the polish becomes high, the viscosity can be adjusted to 20 p or less by mixing fine Si02 powder with silanol groups in 1 vol% to 3 vol% of the above Mg0 fine powder. can be retained.

By the polishing method using Mg○ fine powder according to the present invention described above, it is possible to process the surface of a polycrystalline ferrite material into a precision flat surface, and by applying the above-mentioned specific conditions, an extremely good precision flat surface ( Surface roughness of 30mm or less and crystal step height of 30A or less) can be obtained.

Next, a description will be given based on a specific example.

Use Mg0 with the properties shown in Table 1 below, suspend it in pure water to make a polishing liquid, use a cloth and Sn plate as a polisher, and rotate it at a ratio of 4 pm to reduce the Mn- Zn
A polycrystalline ferrite material was polished by applying a load of 0.5 kg/arc2.

As a result, when the viscosity of Example 1 was 14 $P, workability was good and a precision flat surface with a surface texture of 30 A or less was obtained.

On the other hand, when the viscosity of Example 2 was 85 p, there was no workability and a precise flat surface could not be obtained.

On the other hand, when 2 ol % of Si02 fine powder was mixed with respect to Mg0 in a polishing liquid equivalent to that of Example 2, workability equivalent to that of Example 1 was obtained, and the viscosity was adjusted. I understand that. Table 1 (In the examples with a particle size of 8 or more, it is clear that the viscosity of the polishing liquid has a great effect on the workability, and it can be seen that polishing according to the present invention under specific conditions is effective.

Claims (1)

[Claims] 1. A polycrystalline ferrite material having a particle size of 0.001 μm to 0.
．． 0.5vol%~20vo of 05μm MgO fine powder
A precision polishing method for polycrystalline ferrite, characterized in that polishing is carried out using a polishing solution having a viscosity of 200 Cp or less in an alkaline region and suspended in pure water at a concentration of 1%. 2 Polycrystalline ferrite material with a grain size of 0.001 μm to 0
．． 0.5vol%~20vo of 05μm MgO fine powder
When the viscosity of the polishing liquid exceeds 200Cp during polishing using a polishing liquid with a viscosity of 200Cp or less in the alkaline region suspended in pure water so that the silanol group is A precision polishing method for polycrystalline ferrite, which comprises adding 1 vol% to 30 vol% to a fine powder and adjusting the viscosity of a polishing liquid to 200 Cp or less before polishing.