JPS63102019A - 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 the oxide and sulfide of Al, Cr, Ti, Pb, Mn, Sn, Mg, Ca, Sr and Ba on a thin film. CONSTITUTION:The protective film essentially consisting of the graphitic carbon contg. one kind from the oxide and sulfide of Al, Cr, Ti, Pb, Mn, Sn, Mg, Ca, Sr, and Ba is provided on the thin film. The weight of the oxide and sulfide 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 or 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 kind of the oxide and sulfide thereon. The thickness of the magnetic layer 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, since it is difficult to mix lubricants and abrasives into the magnetic nL like in conventional coated magnetic recording media, metal thin film magnetic recording media generally have poor running durability, such as Co-Cr alloys. In the case of a perpendicular magnetic recording disk provided with a film, adhesion occurs between the alloy a tip on the surface and the head after about 100 running passes, and the disk often becomes unable to run.

Therefore, in order to solve this problem, a liquid lubricant was applied to the surface of the magnetic layer, and a solid protective fluor was applied to the magnetic wire 2.
It has been proposed to provide it on the surface. 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 (Japanese Patent Application Laid-Open No. 1997-111036), but the lubricity is poor and therefore the durability is insufficient. I can't get sex.

[Problem that the invention seeks to solve]

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

[Failure to solve the problem]

The present invention provides a magnetic recording medium in which a magnetic metal thin film is provided on a non-magnetic substrate.
Magnetic recording characterized by being provided with a protective film mainly composed of graphitic carbon containing at least one selected from oxides and sulfides of Pb, Mn, Sn, Mg, Ca, Sr, and Ba. Regarding media.

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 (XPS) shows that of graphite.

The weight of the above-mentioned oxides and sulfides contained in the above-mentioned protective film mainly composed of graphitic carbon is 10%.
The content is preferably 0.3-t% or less.

The magnetic metal thin film of the present invention may include ferromagnetic metals such as Fe, C□, Ni, or pe-co, F'e-Ni, Co-
N I, Fe-31, Co-Cr.

Co-V, C□ -S m, C□ -pt, C
Ferromagnetic alloys such as Op, Co-N1-P, and Fe-Cr-Co are used, or ferromagnetic alloys such as those to which trace amounts of metal elements are added are 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 non-magnetic substrate by a method such as vacuum evaporation, sputtering, ion blasting, plating, etc. A protective film whose main component is graphitic carbon containing at least one kind of sulfide may be formed by vacuum evaporation, sputtering, or the like.

In this case, the magnetic film is laminated using two different magnetic materials.
Alternatively, it may be a single layer type with a base layer provided.

Alternatively, a laminated type having an intermediate layer may be used. In any case, the appropriate thickness of the magnetic film is about 0 to 2 μm.

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, so it is preferably /θ~1000A! 10-
It is about 200 large.

〔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 with a thickness of 2!0Qλ was deposited on this substrate by sputtering in Ar gas using CoCr as a target.
A thin film was formed.

Next, binary simultaneous sputtering is performed in Ar gas using a graphite target and a desired oxide or sulfide target, and a graphite-like carbon containing at least one of the above substances is deposited on the CoCr thin film as a main component. Various protective films with a thickness of 200 mm were prepared.

Process these into a disc shape with a diameter of 3.3 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.
The running durability was tested by rotating it at r, p, and m and measuring the number of passes until the friction coefficient suddenly increased.

The content of the above substances 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 was also prepared in which a protective film with a thickness of 200 mm was provided, the main component of which was graphite 6 monolithic carbon, which did not contain the above-mentioned substances, and this was used as a comparative example.

The results obtained are shown in Tables 1 to 1+. As is clear from the table, the medium provided with the protective film mainly composed of carbon containing appropriate amounts of oxides and /''! or sulfides of the present invention is different from the protective film mainly composed of carbon that does not contain these. It has superior running durability compared to media with a . It was confirmed that the media with excellent properties had no deposits or scratches, and the media containing no metal had no scratches but had deposits.

Table 1 Table 1 Table 3 Table μ Table 5 Table 6 Table 7 Table ♂ Table io Table 1/l- Table 1I Table 12 Table l 3- Table 13 Table 1 ≠Table -/+- [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.

Claims (1)

[Claims] In a magnetic recording medium in which a magnetic metal thin film is provided on a nonmagnetic substrate, Al, Cr, Ti, Pb, Mn,
Magnetic recording characterized by being provided with a protective film mainly composed of graphitic carbon containing 10% by weight or less of at least one selected from oxides and sulfides of Sn, Mg, Ca, Sr, and Ba. Medium.