JPS5835254B2 - Corrosion resistant high permeability alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sendust-based high magnetic permeability alloy with improved corrosion resistance.

Conventionally, permalloy, ferrite, etc. have been used as magnetic materials for magnetic helad cores, but as a result of the advent of chromium oxide tape, which easily wears the mating material, and the spread of magnetic cards, permalloy has problems in terms of wear, and ferrite In particular, when a magnetic card is used, the chipping resistance is extremely insufficient. Therefore, Al 5i-Fe based sendust alloys are attracting attention as a magnetic material to compensate for these drawbacks.

However, when these sendust alloys are used as the core material of a magnetic head, the core material alloy may be corroded by the binder liquid leached from the tape under high temperature and high humidity conditions due to sliding contact with the magnetic tape, and the core material of the tape binder may also corrode. Head characteristics (recording and playback characteristics) are impaired by adhesion to the surface, and in severe cases, the tape may become unable to move on the core surface.

It has also been recognized that new problems arise when used in coastal areas, such as salt water corrosion or corrosion occurring in the gaps between core materials that are brought together via spacers.

In order to solve these problems, the present inventors conducted extensive studies on improving the sendust alloy composition, and found that Si4~
By adding a total of 0.01 to 3.5 wt% of one or both of An and Ag to a sendust alloy consisting of 11 wt% of AA, 3 to 8 wt% of AA, and the balance Fe, corrosion resistance to the tape under high temperature and high humidity conditions can be achieved. The corrosion resistance against salt water and slit corrosion was greatly improved, and the intended purpose was achieved.

In the present invention, the addition amount of either one or both of Au and Ag is limited to a total of o, oi ~ 3.5 wt. The reason why the above corrosion resistance improvement effect is less than 1 wt. % or more, the magnetic properties, particularly the magnetic permeability, decrease, making it impossible to use it effectively as a magnetic rad core material.

EXAMPLES In order to further clarify the effects of the present invention, Examples will be described in detail below.

Example 1 The alloy materials shown in Table 1 were cut and ground in 1 oocc of an abrasive solution obtained by immersing a magnetic tape (chromium oxide tape) for one magnetic recording cassette in 21 distilled water at 25°C for one week. Samples with the following shapes obtained by
The amount of Fe leached into the attrition solution (xoocc) after immersion for a week was measured by atomic absorption spectrometry.

As a result of analysis, the Shoma food solution contains Cl ions, Na ions, and C
It has been confirmed that it contains a ions and has a pH of 4.2.

Sample shape: 10X10X50 (Surface finished by grinding with 1 grindstone) No. 20 G, C 25°C From the results in Table 1, the alloy of the present invention has a lower amount of Fe elution compared to conventional alloys, and has better corrosion resistance to tape constituent materials. It turned out to be extremely good.

Example 2 10X 50X5Qmm from the alloy with the composition shown in Table 2
A sample with dimensions of 50 x 50 was cut out, one side of 50 x 50 was finished with a patch mirror surface, and polysaline solution at 35°C was sprayed on this side for 6 hours.

After spraying, the area of the discolored portion was measured using a branimeter, and the area ratio of the discolored portion to the total area of the sprayed surface is shown in Table 2.

These results show that the alloy of the present invention is clearly less likely to discolor than conventional alloys and exhibits excellent corrosion resistance against salt water.

Example 3 A sample with dimensions of 1010 x 5050 was cut from the alloy with the composition shown in Table 2, and one side of the 50 x 50 was finished with a puff to a mirror finish.
2X5 with one side of the same <50X50 polished to a mirror surface
A Ti plate measuring 0 x 50 mm and a mirror surface were put together, tied together with Ti wire, and immersed in 50% saline solution for 10 minutes to allow the salt water to soak into the gaps.Then, the plate was taken out and placed in the atmosphere at 25°C and 75° humidity. The state of discoloration of the finished surface of the sample after being left for day and night (24 hours) was examined.

The results are shown in Table 2 as the area ratio ψ of the slit-corrosion area.

The method of investigating and displaying the state of discoloration is the same as in Example 2.

From the results in Table 2, it can be seen that the alloys of the present invention are far less discolored than conventional alloys and have much better corrosion resistance against crevice corrosion.

Claims (1)

[Claims] I Si4-11wt%, A73-8wt%, Au
and/or Ag O, 01-3.5 wt%, balance F
A corrosion-resistant high magnetic permeability alloy characterized by consisting of e.