JPS60125353A - Wear-resistant alloy having high magnetic permeability - Google Patents

Abstract

PURPOSE:To obtain an alloy having high saturation magnetic flux density, high effective permeability and superior wear resistance by adding specified percentages of Si, Al, Ru and B to Fe. CONSTITUTION:An alloy consisting of, by weight, 6-11% Si, 4-8% Al, 0.05- 10.0% Ru, 0.005-0.5% B and the balance Fe is prepd. When the alloy is used as the material of the core of a magnetic head, strong leakage magnetic flux can be obtd. even in case of a narrow gap.

Description

[Detailed description of the invention] The present invention has a high effective magnetic permeability (μe), high saturation magnetic flux density (BS), and excellent wear resistance, and is particularly strong even in narrow gaps as magnetic herad core material. The present invention relates to a high permeability alloy that can obtain leakage magnetic flux.

Permalloy and ferrite have been used in magnetic heads of conventional magnetic recording devices, but permalloy has poor wear resistance, and ferrite has a low saturation magnetic flux density (BS). In recent years, with the advancement of magnetic recording technology, the gap +l+ of magnetic heads has tended to become smaller due to the need to improve recording density. Density (BS
) is now required.

For this reason, AJ! 5wt% (hereinafter wt% is simply abbreviated as %)
A high magnetic permeability alloy called Sendust, which consists of 10% , 3i, and 85% Fe, has been attracting attention. This alloy has excellent magnetic properties, especially high saturation magnetic flux density (Bs
), compared to permalloy, it showed relatively high abrasion resistance against soft recording media such as audio tapes, but its abrasion resistance was insufficient against hard recording media such as magnetic cards. .

On the other hand, ferrite exhibits high abrasion resistance against soft recording media such as audio tapes1, but it does not have very high abrasion resistance against hard recording media such as magnetic cards, and its saturation magnetic flux density (83) is around 5000. It was low. Therefore, Sendust alloys, which have improved wear resistance by adding small amounts of special elements to Sendust, have been put into practical use and are rapidly becoming popular, but their wear resistance is still not sufficient.

Recently, in order to further improve recording density, magnetic tapes and magnetic cards that use ultrafine powder of metals with high coercive force have been put into practical use instead of conventional metal oxides as recording media. A high magnetic permeability alloy with even higher saturation magnetic flux density (BS >) and high wear resistance is now desired for rad core materials.Therefore, the Sendust (Fe-
Attempts have been made to improve the wear resistance without reducing the effective magnetic permeability (μe) or saturation magnetic flux density (Bs) by adding various elements to (A, e-s+ternary alloy).

However, the magnetic properties of sendust are extremely sensitive to the composition, and the addition of a small amount of a fourth element reduces the magnetic properties to a large degree. Therefore, in order to maintain the necessary magnetic properties, Fc
, AJ2, and the addition of elements other than Si had to be limited to small amounts, and as a result, it was considered impossible to significantly improve wear resistance.

In view of this, the present invention provides a hard recording medium with a ferrite layer.
- As a result of various studies to develop a high magnetic permeability alloy with better wear resistance and higher saturation magnetic flux density (BS) than ferrite, we found that
S) and a high permeability alloy with excellent wear resistance were obtained, Si6-11%, AjA4-8%, RuO,
05-10.0%, BO, 005-0.5%, balance Fe
It is characterized by consisting of.

That is, as a result of various studies on the effects of various additive elements on the Sendust (Fe-s+-A ternary alloy), the present invention found that when RU and 8 are added at the same time, the effective magnetic permeability (μe) and saturation magnetic flux density of the alloy decrease. We found that the wear resistance was significantly improved compared to when RLI and B were added alone, and the magnetic properties were improved, especially when a small amount of Ru was added. As a result, the alloy of the present invention is WIC. RL applicable to the alloy of the present invention
The effect of adding I and B exhibits a phase-opening effect that is greater than the mutual effect of improving wear resistance by adding Ru and B alone, and can significantly improve the wear resistance of the alloy.

However, in the present invention, the alloy composition is changed to 1, E(
7) Lt m (7) Fl! dac. a. .

a. .・(The reason why we limited the Si content to 6 to 11% and the AJ2 content to 4 to 8% is because even if either 3i or A( is less than the lower limit, if it exceeds the upper limit, the magnetic properties, especially the effective permeability (
This is because μe) is so high that it cannot be used for low torsion, magnetic helad cores, etc. Also, the Ru content is 0.0
The taU content was limited to 5 to 10.0% when the taU content was 0.0%.
If it is less than 5%, the effect of improving wear resistance due to the phase opening effect with B is insufficient, and if it exceeds 10.0%, harmful phases will crystallize and reduce the effective magnetic permeability (μe) and saturation magnetic flux density (BS). This is the 17th day when the value suddenly decreased.

Furthermore, the reason why the B content 4 was limited to 0.005 to 0.5% is that if the B chain content is less than 0.005%, the wear resistance improvement effect due to the phase opening effect with +<U is insufficient. This is because as the amount exceeds 0.5%, the magnetic properties, especially the effective magnetic permeability, deteriorate significantly.

The present invention will be explained below with reference to examples.

Electrolytic iron with a purity of 99.9%, Al with a purity of 99.99%, Si with a purity of 99.99%, +<U with a purity of 99.9%, and B with a purity of 99% are mixed in various proportions, and this is mixed into alumina. Using a crucible, vacuum (3~7X10-3sato1(+)
It was melted in a convex frequency melting furnace and cast into a cast iron mold to have a thickness of 25#111 and a width of 25mm having the composition shown in Table 1.
m.

An ingot with a length of 160 mm was produced.

These were soaked at a temperature of 1000°C for 24M1, and then a sample for measuring magnetic properties with an outer diameter of 8 m, an inner diameter of 4M%, and a thickness of 0.2 m was cut out by electric discharge machining, wire saw cutting, and lapping, and then heated for 1000 m in a hydrogen stream. Effective magnetic permeability (μ
e) and the saturation magnetic flux density (BS) was measured when a magnetic field of up to 10 oersted was applied.

In addition, a square wear test piece measuring 12#I in length, 14M in width, and 15M in height was cut out from the soaked ingot, and its - side was cut out by 20mm.
The wear resistance was measured by grinding a curved surface with a radius of 6 m using a No. 00 GC grindstone. These results are listed in Table 1.

The abrasion test was conducted using a card reader device in a constant temperature and humidity chamber at 114°C and 60% humidity.
A wrapping card coated with grains and the above tIIlrf.

When the curved surface is moved in contact, the wear m on the contact surface of the test piece is 1
The number of times the card was bussed until it reached 00 μm was counted.

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As is clear from Table 1, the alloys of the present invention No. 1 to 3
3 has an effective magnetic permeability (μe) of 4,500 to 14,
800, saturation magnetic flux density (Bs) 7,300-10,
500, the number of passes is 7.200 to 45,000, and the wear resistance is significantly improved compared to the conventional alloy Ferrai 1-N0.54 without reducing the saturation magnetic flux density (Bs). It can be seen that 1-<u and B are based on the phase opening effect caused by the simultaneous addition of B.

In other words, the present invention alloy NO, in which 15rendust N0.53 and 0.005% of Ru and 0.005% of B were simultaneously added.
Comparative alloys N O,34 and N O,4 to which 1 (uO,05% or F2O,005%) were added alone, respectively.
As is clear from the comparison with 0, the increase in the number of passes by adding RLI alone is about 100 times, and the increase in the number of passes by adding B alone is about 500 times. On the other hand, r< u
In the alloy of the present invention in which B and B are simultaneously added, the number of passes increases by 4.
, 200 times. Similarly, Sendust No. 53, present invention alloy No. 38, comparative alloy No. 35 and No. 4
1. Sendust No. 53 and invention alloy No. 15 and comparative alloy No. 36 and No. 42, Sendust No.
, s3 and the invention alloy No.

Comparative alloys No. 22, No. 37 and No. No. 43, as well as No. 43, are compared in the same way. As is clear from the comparison, the improvement in wear resistance due to the simultaneous addition of R11 and B in the invention alloy is due to the phase opening effect. I understand.

However, even in alloys in which Ru and B are simultaneously added, the comparative alloys N O, 45 to N O, which are outside the composition range of the alloy of the present invention,
52, the improvement in wear resistance is insufficient or the effective permeability (
It can be seen that the decrease in μe) is significant.

That is, comparative alloy No. 45 with low Ru or B content,
NO, 46 has insufficient improvement in wear resistance C, RL
Comparative alloy No. 47, No. with a large amount of I or B containing Ii,
It can be seen that the effective magnetic permeability (μe) of 48 Teha is significantly reduced.

Furthermore, it can be seen that the effective magnetic permeability (μe) of comparative alloys No. 49 to No. 52'c, whose AJ2 or Si contents are outside the composition range of the alloys of the present invention, is significantly reduced.

As described above, the alloy of the present invention has high wear resistance that exceeds the limits of conventional magnetic herad core materials such as Sendust and Flylite, and also has a saturation magnetic flux coefficient II (BS>) higher than that of ferrite. However, as a magnetic head core, it has remarkable industrial effects such as being able to suppress strong leakage magnetic flux with a narrow gap.

Claims (1)

[Claims] Si6~11wt%, AJ! 4-8wt%, Ru0.0
5-10.0 wt%, Bo, 005-0.5 wt%,
A wear-resistant high magnetic permeability alloy with the remainder being Fe.