JPS6049971B2 - magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides Fe,
A thin film of a magnetic material mainly composed of ferromagnetic metals such as Co and Ni or their alloys or intermetallic compounds is formed by vacuum evaporation,
The present invention relates to magnetic recording media such as magnetic tapes formed by electroplating, chemical plating, sputtering, ion blating, etc.

Recently, as magnetic tapes have become thinner, magnetic thin films of ferromagnetic metals such as Fe, Co, Ni, or their alloys or intermetallic compounds have been deposited on non-magnetic substrates such as polymer films by vacuum evaporation or electroplating. The magnetic recording medium is formed by a method such as a chemical plating method, a sputtering method, an ion blating method, etc., and is used as a magnetic recording medium.

However, due to the nature of such thin film magnetic recording media, there is a problem in that the phenomenon of oxidation of the magnetic thin film cannot be avoided.

Therefore, attempts have been made to form a protective film on the magnetic layer to prevent oxidation.
RhNPdNCr)Al, Si, etc. may be formed by vacuum evaporation, electroplating, or the like, or a polymer film may be applied.

However, in the former case, there are problems such as compatibility at the interface between the magnetic thin film and the protective layer, pinholes in the film plane, and changes in the film composition due to concentration changes in water solution, and the oxidation resistance is not always satisfied. I can't say that I will.

In addition, even in the latter case, the adhesion at the interface between the magnetic thin film and the coated film is not very good, and when the coating is applied thinly enough to keep the loss during recording and playback within the allowable range, in other words, the thickness of the coated film is reduced to 0. When the thickness is less than .2 μm, it is difficult to apply a polymer film to a uniform thickness on the surface of a magnetic thin film due to agglomeration due to surface tension, reflection of irregularities from the substrate surface, etc. The present invention has been made in view of these problems, and as shown in FIG. A thin film 3 of metal nitride is formed with a uniform thickness parallel to the irregularities of the surface.

In addition, in the present invention, the metal nitride thin film 3 may be a metal that is entirely nitrided, or may be a metal that is partially nitrided on the outer surface side of the thin film 3 or on the side of the magnetic thin film 2. .
By the way, the conventional method of forming a nitride film on a metal surface required heating it to a temperature of 10000C or more in an ammonia gas atmosphere, but in the case of magnetic recording media, when heat treatment is performed at a high temperature, , resulting in extremely significant changes in magnetic properties.

Therefore, in the present invention, a thin film of a metal nitride is formed by a known vacuum evaporation method, sputtering method, or ion blasting method in a vapor of nitrogen or a nitrogen compound such as ammonia, which can form a nitride film at a relatively low temperature. conduct.

In this case, the vapor or ions of the material to be evaporated and the nitrogen atoms or ions undergo a direct chemical reaction to form a nitride, so that the temperature of the substrate and thin film can be maintained at 100'C or less. Further, in the present invention, by forming a dense nitride thin film on the magnetic thin film, it is possible to suppress oxidation of the metal magnetic thin film. Even if a pinhole occurs in the nitride film, the metal magnetic thin film will also be exposed to the vapor of nitrogen and nitrogen compounds, so nitride will form in the magnetic thin film itself even in the pinhole area. be done. Such an effect is most effectively exhibited particularly in a method such as sputtering or ion blating that generates a particularly large amount of nitrogen atoms or nitrogen compound ions. By the way, one of the features of nitride is its high hardness, but the magnetic recording medium created in the present invention has a problem that conventional metal thin film magnetic recording media coated with AI, Au, etc. However, due to its high hardness, it exhibits excellent wear resistance.

Moreover, it is known that soft metals such as A] and Au, as mentioned above, cause a significant increase in friction when they come into contact with magnetic heads, making them unsuitable for recording and playing back using contact-type magnetic heads. . On the other hand, according to the present invention, it is possible to create a metal thin film type 3 magnetic recording medium that has sufficient compatibility with a magnetic head compared to conventional magnetic recording media such as magnetic tape coated with magnetic powder. can. *ゝ Note that as the metal material that serves as the base material for the nitride, a material that has the same flexibility as the metal of the underlying magnetic thin film has better adhesion between the nitride and the magnetic thin film. Generally, magnetic thin films are made of Fe.
, CO, Ni, etc. or alloys mainly composed of these metals are used, and the base metals of nitrides are also Fe, CO, etc.
, Ni is used. However, it goes without saying that the elements that form nitrides are not limited to the same elements as these base materials. l Next, specific examples of the present invention will be described.

A film with a thickness of 0.2μ was deposited on a 16μ thick polyethylene terephthalate film maintained at 50°C using a known vacuum deposition method.
An iron thin film was formed, and iron nitride was further formed on top of it. The conditions for creating nitride are: first, the temperature inside the vacuum chamber is 10-6T0r.
After evacuation to below r, nitrogen gas is introduced until the degree of vacuum reaches 10-5 T0rr without closing the exhaust valve, and further ammonia gas is introduced until the vacuum level reaches 5 x 10-4 T0rr. By evaporating iron in a tungsten boat under these conditions, a partially nitrided iron thin film with a thickness of 0.05 μm was prepared. The corrosion resistance of a magnetic recording medium coated with a nitride thin film is determined by immersing it in pure water at a temperature of 40°C.
It was found that even after being kept in a constant temperature bath with a relative humidity of 90% for 150 Ctf, the magnetic properties did not change from those immediately after vapor deposition.

On the other hand, for the sample that was not subjected to nitride treatment, the coercive force Hc and saturation magnetic flux B after being held in a constant temperature bath under the same conditions for 150 hours
A decrease of approximately 10% was observed in s. The characteristics at that time are shown in the table below.

Next, in this example, the nitride film formed on the magnetic thin film 4' was set on the magnetic recording medium by applying a load using a device that attached a 4φ steel ball to the tip and could apply an arbitrary load. After that, horizontally move the magnetic recording medium to 1c! A comparison of the amount of peeling of the magnetic thin film when the magnetic thin film is moved by n, as shown in FIG. 1
Peeling of 8wn occurred, and when a load of 12011 or more was applied, I peeling of 0.2T0n or more occurred.

Further, in the magnetic recording medium according to the present invention provided with a nitride thin film, as shown by curve b, the magnetic thin film becomes zero under a load of 80y.
．． 17077! When a load of 120y or more was applied, the amount of peeling gradually increased, but by forming a nitride thin film, the amount of peeling due to so-called catching can be significantly reduced. confirmed.

In the examples, only iron nitrides were described, but similar effects were confirmed with elements or alloys that easily form nitrides, such as titanium, chromium, manganese, nickel, cobalt, niobium, and tantalum.

As described above, according to the present invention, it is possible to obtain an extremely excellent magnetic recording medium that can improve the corrosion resistance and wear resistance of the magnetic recording medium and prevent deterioration of magnetic properties. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a magnetic recording medium according to an embodiment of the present invention, and FIG. 2 is a relationship between the load applied to the magnetic thin film and the amount of peeling in a conventional magnetic recording medium and a magnetic recording medium according to the present invention. 1: Non-magnetic substrate, 2: Magnetic thin film, 3: Metal nitride thin film.

Claims (1)

[Claims] 1. A magnetic thin film mainly composed of metals, alloys thereof, or intermetallic compounds is formed on a non-magnetic substrate, and a thin film of metal that is partially or completely nitrided is formed on the magnetic thin film. magnetic recording media.