JPS6246425A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and wear resistance by using an Ni-Mo-Fe alloy to constitute an inorg. protective layer and limiting the component compsns. of respective metallic elements. CONSTITUTION:The inorg. protective layer 4 of a magnetic recording medium successively provided with a thin magnetic metallic film layer 3, on a nonmagnetic substrate 1 coated with a nonmagnetic metallic layer 2 and the inorg. protective layer 4 and solid lubricating layer 5 on the magnetic layer 3 is formed of the Ni-Mo-Fe alloy. The Ni-Mo-Fe alloy is preferably composed of 25-35wt% Mo, 3-10wt% Fe and the balance Ni, by which the corrosion resistance and wear resistance are improved. A Co-Ni alloy having the component compsn. Co:Ni=1:1-9:1 or a Co-Cr alloy having the component compsn. Co:Cr=7:3-9:1 is preferable for the alloy to be used for the thin magnetic metallic film layer, by which the recording characteristics are improved. Silicon dioxide, carbon, etc. are used for the solid lubricating layer 5, of which carbon is more preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION AND SUMMARY OF THE INVENTION The present invention relates to magnetic recording media, and more particularly to protecting recordings on magnetic recording media, that is, providing a protective film on magnetic disks, magnetic drums, and the like.

The magnetic recording media used in magnetic disk drives and magnetic drum drives have problems in terms of resistance to wear, weather resistance, and corrosion resistance against mechanical contact with magnetic heads.

Therefore, these magnetic recording media are usually provided with a protective film. This protective film is required to have smoothness, uniformity, abrasion resistance, corrosion resistance, etc.

It is necessary that the thickness thereof is small, that is, it is a thin film.

Conventionally, it has been known to provide an inorganic protective layer or a lubricating layer (protective layer) such as a solid lubricant on top of the inorganic protective layer as a protective film for magnetic recording media such as magnetic disks and magnetic drums. As, rhodium (Rh), chromium (
Cr) (Japanese Patent Publication No. 52-18001), nickel-phosphorus (Ni-P) (Japanese Patent Publication No. 54-33726),
Other rhenium (Re), osmium (○s), ruthenium (Ru), silver (Ag), gold (Au), i$f
(Cu), platinum (Pt), palladium (Pd), (Japanese Patent Publication No. 57-6177), and nickel-chromium (
Ni-Cr) (Japanese Patent Publication No. 57-17292), etc. are used, and as solid lubricants, inorganic and organic lubricants,
For example, silicon compounds, such as silicon dioxide (SiO2)
, silicon oxide (S i O), silicon nitride (S i
4Ns) etc. (Japanese Patent Publication No. 54-33726), polysilicic acid or silane coupling agents such as tetrahydroxysilane, polyaminosilane, etc. (Japanese Patent Publication No. 59-3
9809) and carbon.

However, the metals or alloys used in these conventional protective films, especially inorganic protective layers, cannot be said to sufficiently improve the abrasion resistance, weather resistance, or corrosion resistance of magnetic recording media, and even better protective films are not yet available. The appearance of this was strongly desired.

As a result of intensive research to improve the above points, the inventors of the present invention have developed a specific inorganic protective layer for the protective film of the magnetic recording layer in magnetic recording media, especially hard disk type magnetic recording media. The inventors have discovered that the above problems can be solved by employing a protective layer made of an alloy, and have arrived at the present invention.

Namely, one aspect of the present invention is a metal thin film magnetic layer on a nonmagnetic substrate.

In a magnetic recording medium in which an inorganic protective layer and a solid lubricant layer are sequentially provided on the magnetic layer, the inorganic protective layer is made of Ni-Mo-
The present invention relates to a magnetic recording medium characterized in that it is made of an Fe alloy.

The Ni-Mo-Fe alloy used in the present invention has a composition of Mo
: 25-35% by weight, Fe: 3-10% by weight, and Ni:
The remaining ones are preferred. With the above composition range, satisfactory corrosion resistance and wear resistance can be obtained.

These Ni--Mo--Fe alloy protective layers are formed on a metal thin film magnetic layer formed on a nonmagnetic substrate by an adhesion method such as sputtering, vacuum evaporation, ion blasting, or plating.

Examples of the nonmagnetic substrate used in the present invention include metals such as aluminum and aluminum alloys, glass, ceramics,
Although engineering plastics and the like are used, aluminum or aluminum alloy is usually used mainly from the viewpoint of cost and stable supply.

Mechanical rigidity, hardness, and workability can also be improved by providing a thin film such as an anodized film or a nickel-phosphorus plating film on the surface of the aluminum or aluminum alloy substrate.

Further, by providing a metal chromium layer as a surface layer of the nonmagnetic substrate, reliability of recording characteristics can be improved.

The magnetic metal or alloy used in the metal thin film magnetic layer of the present invention includes iron, cobalt, nickel and other ferromagnetic metals, Fe-Co, Fe-Ni, Co-Ni, C
o-Cr, Fe-Rh, Fe-Cu, Fe-Au,
Co-Cu, Co-Au.

Co-Y, Go-La, Co-Pr, C
o-Gd, Go-8m, Co-Pt, Ni-C
u, Fe-Co-Nd, Mn-B t, Mn-3
b, magnetic alloys such as Mn-Al.

Among these, a Co-Ni alloy is preferred, and one in which the component ratio is Co:N1=1:1 to 9:1 is particularly preferred. Outside this range, recording characteristics deteriorate. Even better properties can be obtained by adding Cr to the Co-Ni alloy. The amount of Cr added is Co+
0.1 to 25% of Nt is preferable. If it is less than 0.1%, the effect is not clear, and if it is more than 25%, the recording characteristics deteriorate.

Further, a Co--Cr alloy is also preferable, and in particular, one having a component ratio of Co:Cr=7:3 to 9:1 is preferable. Outside this range, recording characteristics deteriorate.

The magnetic metal thin film is coated directly or through a nonmagnetic thin film layer on a known substrate such as a metal plate such as an aluminum plate or a stainless steel plate or an inorganic plate such as a glass plate. may be formed by vacuum deposition, sputtering, ion blating, plating, or other methods.

In addition, for the solid lubricant layer provided on the inorganic protective layer, conventionally known inorganic lubricants are used, such as silicon compounds such as silicon dioxide, silicon oxide, and silicon nitride, carbon,
Examples include M o 82.

Among these, carbon is preferred.

The lubricating layer can be provided by an adhesion method such as vacuum evaporation, ion blating, plating, or sputtering, or by a spin cord or the like.

Run 1 By using a protective film made of Ni-Mo-Fe alloy as the inorganic protective layer of the metal thin film magnetic layer of the hard disk type magnetic recording medium, in particular, the composition ratio is MO = 25 to 35% by weight, Fe: 3 to By using an alloy consisting of % by weight and the balance of Ni as a protective film, the mechanical rigidity, abrasion resistance, and weather resistance or corrosion resistance of the magnetic recording medium can be significantly improved.

The present invention will be explained in more detail with reference to Examples of S-L Doctors, but it goes without saying that the present invention is not limited thereto.

11-2 [ After a metallic chromium layer was attached as a non-magnetic metal layer to a disc-shaped aluminum alloy to form a non-magnetic substrate, a magnetic layer having the composition shown in Table 1 was provided by high-frequency sputtering method, and further, A protective layer 100A having the composition shown in Table 1 was provided on this magnetic layer by the same high frequency sputtering method. moreover,
A carbon lubricant layer 100A was provided on the surface of this inorganic protective layer by high frequency sputtering.

Ratios AB and D A metal chromium layer was attached as a non-magnetic metal layer to a disc-shaped aluminum alloy to form a non-magnetic substrate, and then a magnetic layer having the composition shown in Table 1 was provided by high-frequency sputtering, and further,
Also on this magnetic layer.

An inorganic protective layer 100A having the composition shown in Table 1 was provided by high frequency sputtering. Furthermore, a carbon lubricant layer 10 is applied to the surface of this inorganic protective layer by high frequency sputtering.
08 was established.

A metal chromium layer was attached as a nonmagnetic metal layer to a disk-shaped aluminum alloy to form a nonmagnetic substrate, and then a magnetic layer having the composition shown in Table 1 was provided by high frequency sputtering.

A carbon lubricant layer 200A was provided on the surface of this magnetic layer by high frequency sputtering.

Samples created in Examples 1 to 8 and Comparative Examples A to D
Table 1 shows the results of a weather resistance test performed on the samples prepared in . The results of the weather resistance test were expressed as the rate of increase (fold) in the number of errors per disk recording immediately after the sample was prepared and after it was left in an environment of 60° C. and 90% RH for two months. That is, the lower the increase rate of the number of errors (the closer it is to 1°0), the better the weather resistance of the disk is.

Here, the rate of increase in the number of errors (times) is the rate of increase in the number of errors (times) = (number of errors after being left in an environment of 60°C and 90% RH for 2 months) / (number of errors immediately after sample preparation). It is expressed by the formula.

The number of errors per disc recording was measured using a certifier, and the slice level was set to 55% for missing and 35% for extra.

As is clear from Table 1, by using the inorganic protective film of the present invention, a thin film magnetic recording medium with excellent weather resistance can be obtained.

As is clear from the above examples, by employing the inorganic protective layer of the present invention and combining it with the inorganic lubricating layer of the magnetic layer, a thin film magnetic recording medium that can withstand practical use can be obtained. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a magnetic recording medium according to the present invention. In FIG. 1, 1 is a non-magnetic substrate, 2 is a non-magnetic metal layer,
3 is a thin film type magnetic layer, 4 is an inorganic protective layer, and 5 is a solid lubricant layer.

Claims (5)

[Claims] (1) A magnetic recording medium comprising a metal thin film magnetic layer on a nonmagnetic substrate, and an inorganic protective layer and a solid lubricant layer sequentially provided on the magnetic layer, in which the inorganic protective layer is made of a Ni-Mo-Fe alloy. A magnetic recording medium characterized by: (2) Ni-Mo-Fe alloy contains Mo: 25 to 35% by weight
, Fe: 3 to 10% by weight, and Ni: the balance. (3) The metal thin film magnetic layer is a thin film of an alloy whose main components are Co and Ni, and the component ratio is Co:Ni=1:1 to 9.
The magnetic recording medium according to claim 1 or 2, which is: (4) The metal thin film magnetic layer is a thin film of an alloy whose main components are Co and Cr, and the component ratio is Co:Cr=7:3~
9:1. The magnetic recording medium according to claim 1 or 2, wherein the ratio is 9:1. (5) The magnetic recording medium according to claim 1, 2, 3, or 4, wherein the solid lubricant layer is a carbon film.