JPS63102014A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To eliminate the deposits on a magnetic head and to improve running durability by providing a protective film essentially consisting of graphitic carbon contg. <=10wt% at least one kind selected from Co, Fe and Ni on a thin film. CONSTITUTION:The protective film essentially consisting of the graphitic carbon contg. one kind selected from Co, Fe and Ni is provided on the thin film. The weight of the Co, Fe and Ni to be incorporated into the protective film is preferably 0.5-5%. The thin film which is formed of a ferromagnetic metal such as Fe, Co or Ni or ferromagnetic alloy such as Fe-Co or is formed by adding a slight amt. of metal elements, etc., thereto is used for the thin magnetic metallic film. The formation of a magnetic recording medium is executed by first forming the thin magnetic metallic film by vacuum deposition on a nonmagnetic substrate and further, forming the protective film essentially consisting of the graphitic carbon contg. at least one kind among Co, Fe and Ni by vacuum deposition, sputtering, etc., thereon. The thickness of the magnetic film is specified to about 0.1-2mum and the thickness of the protective film to about 50-200Angstrom .

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium, and more particularly to a metal thin film type magnetic recording medium that has excellent running durability.

[Conventional technology]

In recent years, as the density of recording media has increased, so-called metal thin film magnetic recording media have been attracting attention in place of conventional coated magnetic recording media.

However, metal thin film magnetic recording media generally have poor running durability because it is difficult to mix lubricants or abrasives into the magnetic layer unlike conventional coated magnetic recording media. In the case of a perpendicular magnetic recording disk provided with a perpendicular magnetic recording disk, adhesion or the like occurs between the alloy layer on the surface and the head after about 100 running passes, and the disk often becomes unable to run.

In order to solve these problems, it has been proposed to apply a liquid lubricant to the surface of the magnetic layer or to provide a solid protective layer on the surface of the magnetic layer. Among these, it is known that providing a protective layer mainly composed of carbon, which is a solid lubricant, on the surface of the magnetic layer is particularly effective in improving running durability.

However, even if such a protective layer containing carbon as a main component is provided on the surface of the magnetic layer, running durability is still insufficient. This is thought to be mainly due to the fact that the deposits formed on the head increase the coefficient of friction with the protective layer.

Furthermore, it has been proposed to incorporate boron, silicon, transition metal elements, etc. into the diamond-like carbon protective film; I can't get sex.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION The present invention provides a thin metal film type magnetic recording medium that does not cause deposits on a magnetic head and has significantly improved running durability.

[Means for solving problems]

The present invention provides a magnetic recording medium in which a magnetic metal thin film is provided on a nonmagnetic substrate, in which C01Fe and N
The present invention relates to a magnetic recording medium characterized in that it is provided with a protective film whose main component is graphitic carbon containing at least one kind selected from i.

The above-mentioned protective layer containing graphite-like carbon as a main component means a graphite-like amorphous film created by a vacuum evaporation method, a sputtering method, or the like. That is, it is a film in which no clear peak is observed by X-ray diffraction, and the plasmon loss energy value of carbon determined by X-ray electron spectroscopy (XPS) K shows that of graphite.

The weight of Co, Fes, and Ni contained in the above-mentioned protective film mainly composed of graphitic carbon is less than IO, and preferably O1~34. is F e s Co s N
ferromagnetic metal such as r, or Fe-Co, Fe-Ni
, Co-Ni, Fe-8i, Co-Cr.

Co-V, Co-8m, Co-Pt, Co-P.

A ferromagnetic alloy such as Co-N1-P or Fe-Cr-Co, or one in which a trace amount of a metal element or the like is added to these alloys is used.

As the non-magnetic substrate, it is possible to use film-like polymeric materials such as polyethylene terephthalate, polyimide, polyamide, etc., disc-shaped polymeric materials such as polycarbonate, polymethyl methacrylate, ceramics such as glass, metals such as aluminum, etc. The shape of the substrate may be a sheet, card, disk, drum, tape, or the like.

In order to create the magnetic recording medium of the present invention, a magnetic metal thin film is deposited on a nonmagnetic substrate by a method such as vacuum evaporation, sputtering, ion blating, or plating, and then Co, Fe.

A protective film whose main component is graphitic carbon containing at least one type of NiO may be formed by vacuum evaporation, sputtering, or the like.

In this case, the magnetic film may be laminated using two different magnetic materials, or may be a single layer type with an underlayer provided. Alternatively, a laminated type having an intermediate layer may be used. In any case, the appropriate thickness of the magnetic film is about O0/~2 μm.

In addition, if the thickness of the protection is too thick, sufficient output will not be obtained during recording and reproduction, and if the force is too low, no improvement in running durability will be seen.
It is about 200^.

〔Example〕

Examples of the present invention will be described below.

A polyimide film with a thickness of 50 μm was used as a nonmagnetic substrate.

CoCr with a thickness of 2300A was deposited on this substrate without trenches by sputtering in Ar gas using CoCr as a target.
A thin film was formed.

Next, Co and Fe were deposited on the graphite target.

Sputtering is performed in Ar gas with a metal layer such as Ni placed on top of the CoCr thin film.

A protective film with a thickness of 200 mm was prepared for each rice, the main component of which was graphitic carbon containing at least one type of Ni.

These are processed into a disc shape with a diameter of 3.5 inches,
It was incorporated into a commercially available disc jacket.

After recording with a commercially available floppy disk drive, toOr, while monitoring the playback signal and friction coefficient.
Running durability was tested by rotating at speeds p and m and measuring the number of passes until the friction coefficient suddenly increased.

The content of Co, Fe, Ni, etc. was determined from the peak ratio of the differential spectrum of each element and carbon measured using Auger electron spectroscopy. It was also similarly confirmed that there was no change in the composition of the constituent elements of the protective film in the film thickness direction.

For comparison, a medium with a protective film of 100^ thickness mainly composed of graphitic carbon not containing Co, Fe%Ni'St was also prepared, and this was designated as Comparative Example J-.

The obtained results are shown in Tables 1 to 1. As is clear from the table, the media provided with a protective film mainly composed of carbon containing appropriate amounts of Co, Fe, and Ni are more effective than the media provided with a protective film mainly composed of carbon that does not contain these. Excellent running durability. As a result of observing the heads under a microscope, media with high metal content and poor running durability had no deposits but were scratched, while media with excellent running durability had no deposits or scratches and contained metal. Although there were no scratches on the media that had not been tested, it was confirmed that there were deposits on the media.

Table 3 Table 1 [Effects of the Invention] The present invention provides a magnetic recording medium that does not cause deposits on the magnetic head and has significantly improved running durability.

Claims (1)

[Claims] In a magnetic recording medium comprising a magnetic metal thin film provided on a non-magnetic substrate, a protective film mainly composed of graphitic carbon containing at least 10% by weight of at least one selected from Co, Fe, and Ni on the thin film. A magnetic recording medium characterized by being provided with.