JPH053655B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium in which a magnetic layer is formed by a thin film deposition method, and particularly to a magnetic recording medium that is excellent in corrosion resistance and characteristic stability of the magnetic layer.

In recent years, research and development into manufacturing magnetic recording media using thin film deposition methods such as vacuum evaporation, sputtering, and plating has become more active. Magnetic recording media made by these manufacturing methods very well satisfy the conditions for high-density recording, such as high residual magnetic flux density, large coercive force, and thin magnetic layer.

Conventionally, Co has been used as the magnetic material for this recording medium.
Alloys whose main components are Ni and Ni are mainly used.
Among these, a Co-20%Ni alloy is being widely studied.
The reason is that this alloy has relatively good corrosion resistance,
This is said to be because alloys containing 70% or more Co have an hcp structure, making it easy to control magnetic anisotropy and making it easy to achieve excellent in-plane anisotropy.

However, this alloy is extremely expensive because it contains 70% or more Co, usually around 80%, and Co has the problem that its price fluctuates greatly due to changes in the international situation. Corrosion resistance is also insufficient for severe environmental conditions.

Therefore, in order to improve the above-mentioned drawbacks, the present invention
It is an object of the present invention to provide a magnetic recording medium that can be stably supplied at low cost by reducing the content of Make it the main purpose.

The present invention provides a magnetic recording medium in which a magnetic layer is formed by a thin film deposition method, in which the composition of the magnetic layer is (Fe _1-x C _x ) _1-(a+b+c) Ni _a Cr _b M _c (M is At least one element selected from Ti, Zr and Hf), with a composition ratio of 0<X0.5, 0.05a
It is characterized by being 0.20, 0.01b0.15 and 0.005c0.15, and can be used for thin films made by induction heating evaporation, resistance heating evaporation, electron beam evaporation, sputtering, ion plating, plating, etc. It can be formed using a deposition method.

As the magnetic layer material, the sum of Co element and Fe element is
It was found that by replacing Co element with Fe element so that Fe becomes the main component at 50 wt% or more, magnetic properties equivalent to or higher than those of conventional Co-Ni alloys can be obtained. However, although replacing Co element with Fe element deteriorates corrosion resistance, addition of Cr element is effective in improving corrosion resistance. Furthermore, Cr
It has been found that by adding at least one element such as Ti, Zr, or Hf at the same time as the element, corrosion resistance and stability of magnetic properties are improved.

In the magnetic material used in the present invention, Fe,
Each of the elements Ni, Cr, Ti, Zr, and Hf has the following effects. The Fe element increases the magnetic moment per atom, increases the residual magnetic flux density Br, and at the same time increases malleability and prevents the occurrence of cracks and cracks in the magnetic layer. On the other hand, as mentioned above, as the Fe element increases, the corrosion resistance deteriorates rapidly and at the same time the residual magnetic flux density increases.
The effect of increasing Br is rather reduced when the Fe element increases beyond a certain level. In addition, Ni improves corrosion resistance and malleability, and prevents cracks and cracks in the magnetic layer. In addition, Cr contributes to improving corrosion resistance. In particular, the vapor pressure of Cr is Fe,
Since it is significantly different from Co and Ni, it tends to cause fluctuations in the properties of the magnetic layer, but by partially replacing Cr with Ti, Zr, or Hf, the magnetic properties can be stabilized. However, if too large amounts of Cr, Ti, Zr, and Hf are added, the magnetic properties of the magnetic layer will deteriorate, such as a decrease in Br.

As a result of the above, the composition of a good magnetic layer is (Fe _1-x C _x ) _1-(a+b+c) Ni _a Cr _b M _c (M is at least one kind selected from Ti, Zr, and Hf). element), the composition ratio is 0<x0.5, 0.05a
0.20, 0.01b0.15 and 0.005c0.15, especially Ti, Zr, Hf alone or two or all three in total of 3 to 12 wt%, and Cr is 1
~6wt%, Ni 7~14wt%, Co 17~25wt%,
It is preferable that the remainder be Fe.

The present invention will be explained below with reference to Examples. FIG. 1 shows an apparatus for manufacturing vapor-deposited tape, which is one of the magnetic recording media. A film unwinding shaft 2 is placed inside the vacuum chamber 1.
A winding shaft 3, an intermediate free roller 4, a cooling can 5, a vapor deposition material storage container 7, and an electron beam generation source 8 are arranged. A polyethylene terephthalate film 9 having a width of 100 mm and a thickness of 15 μm is sent from a film unwinding shaft 2 to a film winding shaft 3 via an intermediate free roller 4 and a cooling can 5. The vapor deposition material 6 is placed in a vapor deposition material storage container 7 and placed opposite the cooling can 5, and is heated by an electron beam from an electron beam generation source 8. The heated material becomes a vapor flow 6' and adheres to the film 9 on the cooling can 5 to form a magnetic layer, but the deposition prevention plate 11 prevents the incident angle of the vapor flow deposited onto the film 9 from 60° to 90°. Limited to ゜. Inside the vacuum chamber 1, the degree of vacuum during film formation is maintained at 1×10 ^-4 to 5× by the exhaust device 10.
It was held at 10 ^-6 Torr. The film feeding speed was 10 m/min, and the thickness of the formed magnetic layer was approximately 1000 m/min.
It is Å. FIG. 2 shows the composition of the magnetic layer of the vapor-deposited tape produced by the above method and the results of corrosion resistance and property stability tests. For the corrosion resistance test, the tape prepared according to the above example was placed in a constant temperature and humidity chamber at 60℃ and 90%.
Changes in residual magnetic flux density after being left for 1000 hours were measured. In Figure 2, ◎ means the decrease in Br is less than 3%, and 〇 means 3%.
~5%, Δ is 5 to 10%, and × is 10% or more. In addition, the characteristic stability of the magnetic layer was tested by recording and reproducing using a home-use VTR deck, and recording and reproducing 5 times within a tape length of 100 m.
The length of the section that caused an output fluctuation of % or more was measured. In FIG. 2, ◎ indicates that the section where the output fluctuation occurred by 5% or more was less than 2% of the total, and Δ was 6 to 10%.

Figure 3 shows the playback output when recording and playing back using a home VTR deck. Tape No. 5 of the present invention
Curve 20 shows the playback output of Co-Ni tape No. 12 produced under the same conditions for comparison, and curve 21 shows the playback output of Co-Ni tape No. 12 produced under the same conditions. Tape No. 5 of the present invention is a conventional tape.
Compared to No. 12, the same or 2 dB higher playback output was obtained. Tape Co- No. 1-4, 6-10 in Figure 2
It showed a playback output equal to or higher than that of Ni tape.

As described above, the present invention reduces the content of expensive Co compared to conventional Co-Ni tape, while
It is possible to provide a magnetic recording medium that has performance equivalent to or better in terms of corrosion resistance, stability of magnetic layer characteristics, and reproduction output.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a vapor deposition tape manufacturing apparatus used in this example. FIG. 2 is a table showing the composition and corrosion resistance of the magnetic layer and the results of a characteristic stability test of the magnetic layer. Figure 3 shows the No. 5 tape and Co-
It is a graph showing a comparison of reproduction output at each frequency of Ni tape No. 12. 1...Vacuum chamber, 2...Film unwinding shaft, 3...
...Film winding shaft, 4...Intermediate free roller,
5... Cooling can, 6... Vapor deposition material, 7... Vapor deposition material storage container, 8... Electron beam source, 9...
Polyethylene terephthalate film, 10...
Exhaust device, 11... Deposition prevention plate, 20... Playback output curve of the embodiment of the present invention, 21... Playback output curve of Co-Ni tape.

Claims (1)

[Claims] 1. A magnetic recording medium having a magnetic layer formed by a thin film deposition method on a non-magnetic substrate, wherein the composition of the magnetic layer is (Fe _1-x C _x ) _{1-(a+b+ c)} Ni _a Cr _b M _c (M is at least one element selected from Ti, Zr and Hf) with a composition ratio of 0<X0.5, 0.05a
0.20, 0.01b0.15 and 0.005c0.15. A magnetic recording medium.