JPS5844146B2 - magnetic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic barrier material with excellent corrosion resistance and strain resistance.

Ni-Fe based permalloy is well known as a high magnetic permeability alloy.

Of these, 45 permalloy, which has a relatively low Ni content, is often used as a magnetic barrier material.

However, 45 permalloy tends to rust if used in a humid environment or left in normal air for a long time, so when used as a magnetic barrier material,
It was necessary to apply anti-rust treatment.

Therefore, recently, in order to improve the corrosion resistance of Ni--Fe alloys, permalloy having corrosion resistance in which Cr is added together with Si, Mo, etc. is being put into practical use as a magnetic barrier material.

In terms of ring magnetic properties, these materials have higher magnetic permeability and lower coercive force than conventional 45 permalloy (for example, initial magnetic permeability μi: 20,000 or more, coercive force He: 0.0
150e or less) and can be said to be excellent as a magnetic barrier material.

However, these materials are susceptible to mechanical strain, and when they are actually used in magnetic head shield cases, for example, there is a phenomenon in which the magnetic properties deteriorate significantly during resin molding, and there is still room for improvement in this respect. was.

As a result of repeated experiments to improve the above-mentioned points, the inventors were able to obtain a practically useful magnetic barrier material with a well-balanced corrosion resistance and distortion resistance, with a particular focus on the Ni content. .

The material of the present invention has Ni30-35% and Cr45-35% by weight.
13%, Si 0.1-3.0 and the balance substantially F
It consists of e.

In order to maintain magnetic properties after resin molding, the amount of Ni is preferably 35% or less.

However, when the Ni amount is less than 30%, the saturation magnetic flux density (Bs
) is no longer sufficient.

If Cr is less than 4.5%, corrosion resistance is insufficient, and if it is more than 13%, Bs decreases.

If Si is less than 0.1%, there is no effect of adding it to improve magnetic permeability, and if it is more than 3%, Bs decreases.

Note that the same effect as that of Si addition can be obtained with Mo, W, V,
Nb, Ta, Mn1Ge, Ti, AI, Co, Cu.

It has been confirmed that this can also be obtained by adding .

One embodiment of the present invention will be described below.

Cr and Si are added to Fe-Ni alloy material in various contents and melted by high frequency melting in vacuum or air.
Each of the obtained ingots was repeatedly hot-worked and cold-worked to form a thin plate of 0.5 mm diameter, and a magnetic measuring ring (0.5 mm (thickness) x 45 mmφ) was made from each thin plate.
(Outside diameter)

Next, the magnetic properties and corrosion resistance of each sample piece were tested.

The results are shown in Table 1. Furthermore, each sample was molded with resin and its magnetic properties were measured.

The results are shown in Table 2. As is clear from Tables 1 and 2, the conventional materials (sample numbers 1 to 3) either have poor corrosion resistance or have good initial magnetic properties, but the magnetic properties after resin molding are significantly deteriorated.

In contrast, the material according to the present invention has excellent corrosion resistance and magnetic properties after resin molding.

When this material (corresponding to sample numbers 4 to 6) was actually used as a magnetic barrier material in a magnetic head shield case, it was extremely effective.

As described above, the material of the present invention has excellent corrosion resistance and distortion resistance, and has extremely high practical value.

Claims (1)

[Claims] 1% by weight Ni 30-35%, Cr4.5-13
%, Si 0.1 to 3.0%, and the balance substantially consisting of Fe.