JPS6144935B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic alloy for magnetic head cores that exhibits excellent abrasion resistance in sliding contact with recording media such as magnetic tapes and magnetic cards. In general, Fe-Si alloys are known as low-cost magnetic core materials with high magnetic permeability, and in particular, those with a Si content of 1 to 4.5% by weight (hereinafter, % by weight is simply abbreviated as %) are made of silicon steel. It is used in large quantities in transformer cores. With recent rapid advances in magnetic recording technology, particularly magnetic tape, the use of Fe--Si alloys, which are inexpensive, have high saturation magnetic flux density, and excellent mechanical strength, are being considered for magnetic head cores. However, since the magnetic head core is embedded in resin during head assembly, it is required that the magnetostriction be zero or close to zero. That is, if the magnetostriction is not zero or close to zero, so-called mold deterioration occurs in which magnetic properties such as effective magnetic permeability and coercive force are significantly reduced when embedded in resin. The silicon steel (Si1-4.5%) has positive magnetostriction and cannot be used for magnetic head cores, but
It is known that Fe-Si alloys with a Si content of around 6.5% have magnetostriction of zero or close to zero.
Alloys with compositions close to this are considered promising as magnetic head cores. However, magnetic head cores are required to have low mold distortion and low sliding wear with recording media such as magnetic tapes and magnetic cards, and Fe-Si alloys with a Si content of around 6.5% are suitable for this purpose. Since the abrasion resistance is insufficient, it is desired to improve the abrasion resistance. In view of this, the present invention was developed as a result of various studies.
We discovered that by adding small amounts of Ti and platinum group elements to Si alloys, wear resistance could be significantly improved without deteriorating magnetic properties, and we developed a magnetic alloy for magnetic head cores.Si4. 5-8.5%,
It is characterized by consisting of 0.1 to 7% Ti, a total of 0.05 to 5.0% of one or more platinum group elements, and the balance Fe. That is, the present invention uses Fe-Si with a Si content of around 6.5%.
When various elements were added to the alloy and the wear resistance was investigated, it was found that those containing a small amount of Ti and one or more of the platinum group elements had excellent magnetic properties and wear resistance. After learning this and further considering it, we developed a Fe-Si binary alloy with a Si content of 4.5 to 8.5%.
Ti0.1~7.0% and platinum group elements such as Ru, Rh, Pd,
By containing one or more of Os, Ir, and Pt in a total amount of 0.05 to 5.0%, it has excellent wear resistance and magnetic properties, has close to zero magnetostriction, and hardly causes mold deterioration. We have developed a magnetic alloy for use in magnetic head cores that does not require a magnetic head. However, in the magnetic alloy of the present invention, the Si content is
The reason for limiting the range to 4.5 to 8.5% is that the Si content is
If it is less than 4.5%, the magnetostriction becomes large, and the magnetic properties, especially the effective magnetic permeability μe, decreases significantly due to resin embedding.If it exceeds 8.5%, the magnetostriction becomes large again, and the magnetic properties decrease significantly due to resin embedding.
This is also because the plastic deformability of the alloy decreases, making processing such as rolling difficult. In addition, the Ti content is 0.1 to 7.0.
%, the reason why the content of one or more platinum group elements is limited to the range of 0.05 to 5.0% in total is that the synergistic effect between Ti and platinum group elements increases magnetic properties, especially magnetostriction. However, below the lower limit, the effect of improving wear resistance is not significant, and when the upper limit is exceeded,
This is because in the case of platinum group elements, the magnetic properties, particularly the effective magnetic permeability μe, decreases significantly and the coercive force Hc increases significantly, and in the case of Ti, the alloy becomes brittle and plastic working becomes difficult. Next, examples of the magnetic alloy of the present invention will be described. Electrolytic iron with a purity of 99.99% is mixed with Si with a purity of 99.99%, Ti with a purity of 99.9%, and Ru, Pd, and Pt with a purity of 99.9% in various proportions, and this is mixed in an alumina crucible and a high frequency vacuum melting furnace. The ingots were melted and cast into cast iron molds to obtain ingots having the alloy composition shown in Table 1 and having a length of 1 inch and 200 mm. This was soaked and annealed at 1100℃ for 6 hours, then hot rolled at a temperature range of 1100 to 850℃ to form a thin plate with a thickness of 0.7mm, which was then cut and ground to a thickness of 0.6mm, a width of 3.2mm, and a length of 3.2mm. Finished in a square plate with a diameter of 8.5 mm. After heat-treating these square plates in a hydrogen stream at 1150°C for 2 hours, two sets of 7 stacked plates were placed facing each other in the width direction with a 1.2μ thick Ti foil interposed between them, as shown in Figure 1. Curved surface a with a radius of 10 mm as shown has a width of 6.4 mm and a height of 4.2
Insert it into a brass fixed frame with a rectangular hole b of mm,
It was fixed with resin and the curved surface a was polished with GC No. 2000 to create a dummy head for wear tests. In the figure, c indicates a square plate cut from a thin plate and finished by grinding, and d indicates a Ti foil. This dummy head for abrasion test was attached to a cassette deck (TEAC, AC-9), and was placed with a magnetic tape (TDK, Normal C-90) for 300 hours in a high-temperature, high-humidity tank at a temperature of 30 ± 1°C and a humidity of 75 ± 1%. It was slid and the wear loss was measured. In addition, from the thin plate (0.7 m/m thickness) wrapped to a thickness of 0.2 m/m, an inner diameter of 6 m/m and an outer diameter of
A 10m/m ring was punched out using electrical discharge machining, and this
The effective magnetic permeability (Me) and coercive force (Hc) before and after resin embedding (mold) were measured for a measurement sample heat-treated at 1150℃ x 2 hours, and the degree of mold deterioration was compared with that of conventional alloys. Regarding wear loss, the first
An example of the measurement results of Me and Hc before and after molding is shown in Table 2.

【table】

【table】

【table】

[Table] As can be seen from Table 1, the wear loss tends to decrease with increasing Si in the Si-Fe binary alloys (No. 1, No. 3, No. 5), but the amount of Si8 % (No.
5) is about 9.4μ. Furthermore, even if Ti is added to this (No. 2, No. 4, No. 6), the wear loss hardly changes. On the other hand, the alloy of the present invention (No. 7
~24), the wear amount is significantly reduced, especially for Si6.5
%, Ti1.0%, Pd2.0%, balance Fe (No.14) wear loss is 1.1μ, Si6.5%, Ti1.0%, Ru3.0%, balance
Wear loss of Fe (No.17) is 0.4μ, Si8.0%, Ti0.2
%, Pd5.0%, balance Fe (No.21) wear loss is 0.3
Excellent μ and wear resistance. On the other hand, from the effective magnetic permeability and coercive force measurement results before and after resin embedding in Table 2, mold deterioration is caused by Si content.
It is smallest at around 6.5%, and mold deterioration increases significantly even when it is less than 4.5% or exceeds 8.5%. Also, the influence of one or more of Ti and Pt group elements is less than 7% Ti, If the Pt group element content is less than 5%, it is relatively small and poses no practical problem. however
Even if the Ti content exceeds 7%, the Pt group elements
%, mold deterioration increases significantly and it cannot be used for magnetic head cores. In this way, the present invention significantly improves the wear resistance of the Fe-Si alloy, which could not previously be used in magnetic head cores due to its wear resistance, making it possible to use it as a magnetic head core, and making it possible to manufacture magnetic head cores at low cost. This is something that can be provided and has significant industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a dummy head for wear testing. a... Curved surface of dummy head, b... Square hole,
c... Square plate for testing, d... Ti foil.

Claims (1)

[Claims] 1 4.5 to 8.5% by weight of Si, 0.1 to 7.0% by weight of Ti, and a total amount of 0.05 to 0.05% of one or more of the platinum group elements
A magnetic alloy for magnetic head cores consisting of 5.0% by weight and the balance Fe.