JPS63102017A - 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% one kind selected from boron, boron nitride and boron carbide on a thin film. CONSTITUTION:The protective film essentially consisting of the graphitic carbon contg. one kind selected from the boron, boron nitride and boron carbide is provided on the thin film. The weight of the boron, boron nitride and boron carbide to be incorporated into the protective film is preferably 0.5-5%. The film which is formed of a ferromagnetic metal such as Fe, Co or Ni, ferromagnetic alloy such as Fe-Co or Fe-Ni or is formed by adding a slight amt. of metallic elements, etc., thereto is used for the thin magnetic metallic film. The formation of a magnetic recording medium is executed by first depositing the thin magnetic metallic film on a nonmagnetic substrate and further, forming the protective film essentially consisting of the graphitic carbon contg. one among the boron, boron nitride and boron carbide 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 [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 material as in conventional coated magnetic recording media.
In case of perpendicular magnetic recording disk with o-Cr alloy film 1
After about 00 running passes, adhesion occurs between the alloy on the surface and the head, and the head often becomes unable to run.

In order to solve this problem, it has been proposed to apply a liquid lubricant to the surface of the magnetic layer or to provide a solid protective film on the surface of the magnetic layer. Among these, it is known that providing a protective film mainly composed of carbon, which is a solid lubricant, on the surface of the magnetic film 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 on the head increase the coefficient of friction between the head and the protector.

Furthermore, it has been proposed to incorporate boron, silicon, transition metal elements, etc. into the diamond-like carbon protective film (Japanese Unexamined Patent Publication No. 2003-100002), but the lubricity is poor and therefore the durability is insufficient. is not obtained.

[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 non-magnetic substrate, in which boron, boron nitride,
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 selected from the group consisting of boron carbide and boron carbide.

The above-mentioned protective film 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. In other words, 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 (1xps) shows that of graphite.

The weight of boron, boron nitride, and boron carbide contained in the protective film mainly composed of graphitic carbon is 10 parts or less, and 0. It is preferable that it is j~5.

The magnetic metal thin film of the present invention includes ferromagnetic metals such as Fe, Co, and Ni, or pe-Co, Fe-Ni1Co-Ni, etc.
, 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.

To create the magnetic recording medium of the present invention, first, 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 boron, A protective film whose main component is graphitic carbon containing at least one of boron nitride and boron carbide 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 approximately O0/-j .mu.m.

In addition, if the thickness of the protective film 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 0.00.

〔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.

First, CoCr was deposited on this substrate to a thickness of 2300 mm by sputtering in Ar gas using CoCr as a target.
A thin film was formed.

Next, a graphite target and boron, boron nitride,
Binary simultaneous snottering is performed in Ar gas using a target such as boron carbide, and a protective film with a thickness of 200 mm mainly composed of graphitic carbon containing at least one of the above substances is formed on the CoCr thin film. We created various types of .

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, monitor the playback signal and friction coefficient.
Running durability was tested by rotating at r, p, and m and measuring the number of passes until the friction coefficient suddenly increased.

The content of boron, boron nitride, boron carbide, etc. was determined from the peak ratio of the differential hardness of each element and carbon measured using Auger electron spectroscopy.

Furthermore, it was 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 having a thickness of 200 mm and consisting mainly of graphite-like carbon that does not contain the above-mentioned substances was also prepared, and this was used as a comparative example.

The obtained results are shown in Tables 7 to 3. As is clear from the table, media with a protective film mainly composed of carbon containing appropriate amounts of boron, boron nitride, and boron carbide are different from those with a protective film mainly composed of carbon that does not contain these. Excellent running durability compared to media with 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, it was confirmed that there were deposits on the media.

Table 1 Table 2 Table 3 [Effects of the Invention] The magnetic recording medium of the present invention does not produce deposits on the magnetic head during running, and at the same time has significantly excellent running durability.

Patent applicant: Fuji Photo Film Co., Ltd.

Claims (1)

[Claims] In a magnetic recording medium comprising a magnetic metal thin film provided on a non-magnetic substrate, the thin film mainly contains graphitic carbon containing 10% by weight or less of at least one selected from boron, boron nitride, and boron carbide. A magnetic recording medium characterized by being provided with a protective film as a component.