JPS63231716A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the title medium having excellent durability and corrosion resistance by forming an amorphous protective layer on the surface of a thin ferromagnetic metal layer provided on a base body. CONSTITUTION:The amorphous protective layer 5a is formed on the surface of the thin ferromagnetic metal film layer 3 provided on the base body 1. Since the protective layer consisting of amorphous Cr is formed to a specified depth from the surface of the thin film layer 3, the medium having high homogeneity and extremely excellent corrosion resistance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media. More specifically, the present invention relates to a novel magnetic recording medium with excellent corrosion resistance.

[Prior Art] Although ferromagnetic metal thin film magnetic recording media made by vacuum deposition or sputtering have characteristics suitable for high-density magnetic recording, they are susceptible to wear and damage when sliding with magnetic heads, etc. However, the surface of the magnetic layer is easily corroded during the course of its popularity, which deteriorates running performance.

In order to eliminate these drawbacks, a cobalt oxide film is formed on the surface of this magnetic layer (Japanese Unexamined Patent Publication No. 58-130428,
Japanese Patent Publication No. 58-41439. JP-A-59-83031)
It has been proposed to form a chromium protective film using a wet process.

However, cobalt oxide films are more corrosive at low pH.
Corrosion resistance in the environment is not sufficient. In addition, with regard to chromium protective films, which are generally said to have excellent corrosion resistance, wet methods do not provide sufficient mechanical strength during tape sliding, and vapor-deposited or sputtered chromium protective films cannot satisfy both mechanical strength and corrosion resistance. It has not reached the standard.

[Problems to be Solved by the Invention] The present invention aims to solve the drawback of 1- that the magnetic film is easily corroded in a corrosive environment, thereby providing a magnetic recording medium with excellent corrosion resistance and durability. purpose.

[L stage for solving the problems] In order to solve the problems of the above-mentioned conventional technology, the present inventor continued extensive experiments and prototype production for many years, and as a result, a ferromagnetic metal thin film layer provided on the base 1- It has been discovered that a magnetic recording medium with excellent corrosion resistance and durability can be obtained by forming an amorphous protective layer on the surface of the magnetic recording medium.

Corrosion of magnetic films in corrosive environments is mainly the result of electrochemical reactions, and this seems to be largely due to various inhomogeneities (existence of grain boundaries, composition, etc.) that exist in magnetic films. .

It has been discovered that amorphous alloys have extremely good corrosion resistance due to their homogeneity. In particular, it has been confirmed that in amorphous materials containing elements that tend to form passive films, such as Cr, corrosion resistance is further enhanced by the formation of passive films.

The amorphous protective layer is not limited to Cr. That is, any element (eg, Mo), alloy, or compound that can be amorphized to improve the corrosion resistance and durability of the magnetic film can be used.

Such materials are well known to those skilled in the art.

The amorphous protective layer can be formed by making the surface of the magnetic film amorphous. For example, an amorphous protective layer can be formed on the surface of the ferromagnetic metal thin film layer by irradiating the surface of the ferromagnetic metal thin film layer with argon or nitrogen ions having an acceleration energy of 50 keV or more.

A cross section of a magnetic recording medium obtained by this method is shown in FIG. An amorphous protective layer 5a is formed at a predetermined depth from the surface of the ferromagnetic metal thin film layer 3.

Reference numeral 1 indicates a substrate.

Alternatively, a protective layer is laminated on the magnetic film by a paper deposition method, and by irradiating this protective layer with argon or nitrogen ions with an acceleration energy of 50 keV or more, an amorphous protective layer can be formed. can be formed.

The magnetic recording medium obtained by this method has an amorphous protective layer 5b of a predetermined depth on the surface of the protective layer 7, as shown in FIG.

Alternatively, the amorphous protective film itself can be laminated on the magnetic film 1-. For example, the components of the protective film can be made amorphous by high-frequency sputtering and then laminated onto the magnetic film.

In this method, as shown in FIG. 3, an amorphous protective layer 5C is directly laminated on the magnetic film 3.

Although the thickness of the amorphous protective layer itself is not particularly limited, it is generally preferable to form it to a thickness within the range of 50 to 300 layers. If there are fewer than 50 people, sufficient corrosion resistance and durability improvement effects cannot be obtained. On the other hand, if the number of participants exceeds 300, problems such as spacing loss will occur, which is not desirable.

The thickness of the amorphous protective layer can be changed by controlling the irradiation energy and/or the irradiation time, or by controlling the laminated thickness of the protective layer.

[Example] Hereinafter, the present invention will be explained in detail with reference to examples.

A 10 μm thick polyethylene terephthalate (PET) film was used as the film substrate, and C was used as the ferromagnetic metal.
o-10wt%Ni-10wt%Cr alloy 5X10”
15 by electron beam melting in L1 NiCd at -5 Torr.
Oblique deposition was carried out to a thickness of 0.00 mm.

At this time, oxygen gas is supplied to the steaming chamber from the nozzle at 0.4 J2/m.
The magnetic properties of the formed magnetic film were improved.

The vapor-deposited original fabric thus created was then set in another ion treatment tank, and the surface was irradiated with 80 keV Ar+ ions. The irradiation time was about 1 second.

After 1300 people deposited Co-20wt%Ni as a ferromagnetic metal, Co-10wt%Ni was deposited on -1- of this deposited layer.
The same process as in Example 1 was performed except that -10vt% Cr was deposited and laminated by 200 people.

A vapor deposited film similar to that of Example 1 was prepared except that the step of mixing 11 ions was removed.

Ken Kouki 1 Ion implantation (mixing) - [61 excluding moderation] Except for this, a deposited film similar to that of Example 2 was created.

A corrosion resistance test was conducted on the magnetic recording medium produced as described above.

Popular atmosphere containing 0.5 ppm sulfur dioxide (35°C,
The magnetic films of each example and comparative example were heated at 75% RH
After being exposed for a period of time, the tape was cut into 8 ml width. Connect this with a φ4 SUS fixing pin (surface roughness Ra==
0.1/1 m) at a winding angle of 90°, a 20 g weight was attached to one end of the tape, and a sliding test was performed at a feed rate of 1 m/min.

The results after sliding 100 times are shown in Table 1 below.

When the surface of the magnetic film after this 50-hour exposure was analyzed by ESCA (X-ray photoelectron spectroscopy), the presence of sulfide or sulfate was not observed in the media of Examples 1 and 2, whereas in comparison In each case, the presence of a disturbing amount of cobalt sulfate was observed in the example media.

When the RHEEI (reflection electron diffraction) pattern of these samples was taken before the exposure test, an oxide peak (Coo) of cobalt, the main element, was observed in the medium of the comparative example, whereas an oxide peak (Coo) of cobalt, the main element, was observed in the medium of the comparative example. In the media, it is difficult to distinguish (
It was clear that the surface layer had been mixed due to ion implantation and had become amorphous.

Although the ion implantation process is provided separately in the embodiment, the ion gun can be incorporated into the same device to continuously perform the ion implantation process.

"Effects of the Invention" - As explained above, the magnetic recording medium of the present invention has an amorphous protective film on the surface of the magnetic film.

Compared to conventional oxide protective films, the amorphous protective film of the present invention has higher homogeneity and therefore exhibits extremely superior corrosion resistance. In particular, amorphous materials containing elements that tend to form passive films, such as Cr, exhibit excellent corrosion resistance due to the formation of passive films.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an example of the magnetic recording medium of the present invention,
FIG. 2 is a cross-sectional view of another example of the magnetic recording medium of the present invention, and FIG. 3 is a cross-sectional view of another example of the magnetic recording medium of the present invention. ■...Substrate, 3...Magnetic film + 5a, 5b and 5c...Amorphous protective film, 7...Protective layer

Claims (2)

[Claims] (1) A magnetic recording medium comprising a ferromagnetic metal thin film layer provided on a substrate, characterized in that the ferromagnetic metal thin film layer has an amorphous protective layer on the surface thereof. (2) The magnetic recording medium according to claim 1, wherein the amorphous protective layer is made of amorphous Cr.