JPS62167614A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve corrosion resistance by providing the 1st magnetic layer having cobalt as a component element and 2nd magnetic layer essentially consisting of iron oxide on a nonmagnetic substrate. CONSTITUTION:An aluminum alloy disk, sized 3.5 inches, is used for the nonmagnetic substrate 11 and a nonmagnetic smoothing layer 12 subjected to Ni-P plating and mirror polishing on the surface is formed thereon. The magnetic layer, protective layer, lubricating layer, etc., are formed thereon by a bipolar type high-frequency sputtering device. Cr is further formed an underlying layer 13 for improving the crystallinity of the magnetic layer and the magnetic layer consisting of two layers is constituted thereon by forming Co-Ni as the 2st magnetic layer 15 and Fe3O4 as the 2nd magnetic layer 16. The protective and lubricating layer 17 consisting of a carbon film is provided on the extreme surface layer.

Description

[Detailed description of the invention] [Technical fields where inventions succumb] The present invention relates to magnetic recording media.

[Technical background of the invention]

Most of the magnetic recording media currently in practical use have discontinuous media. The magnetic recording layer of this discontinuous medium is F
e, Fe-Co, Fe, 03. Magnetic particles such as Cry are mixed and dispersed in a binder made of organic resin, and the mixture is coated on a substrate, dried, and fired. However, as the density of recording media has increased in recent years, continuous thin-film media in which the magnetic material is continuous within the medium, in other words, the magnetic layer has become thinner and have a higher coercive force. The film forming method is now shifting to a plating type or a sputtering type.

Under such circumstances, the requirements for magnetic recording media are that the magnetic layer be thin and that sufficient reproduction output can be obtained. The media that are attracting the most attention as such media are Go-Ni alloys containing 20 to 30 at% Ni and Co-Cr containing 18 to 20 at% Cr.
The magnetic layer is made of a system alloy. This type of magnetic recording medium usually has a smooth layer on a non-magnetic substrate, as shown in Figure 2.
On top of this, an underlayer (3) mainly made of Cr is formed, a magnetic layer () is formed on top of this, and a protective and lubricating layer (2) is provided on the outermost surface.

[Problems with background technology]

When a Go-Ni alloy is used as the magnetic layer, a thickness of 500 to 2000 layers is sufficient to obtain sufficient reproduction output. However, the Go-Ni alloy alone has poor corrosion resistance, and to compensate for this, it is necessary to further provide a non-magnetic layer such as Cr with excellent corrosion resistance on the magnetic layer. However, when considering reproduction output, it is generally said that the flying height of the head from the disk must be 2,000 to 3,000. Therefore, the thickness of the non-magnetic layer of nearly 1,000 layers increases the distance from the head to the magnetic layer, resulting in a reduction in reproduction output due to spacing loss.

On the other hand, when a Co-Cr alloy is used as a magnetic layer, although it has excellent corrosion resistance, the problem inherent to the material is that the amount of saturation magnetization is small. I have to take it.

Considering the future trend toward higher densities, the corrosion resistance of Co-Ni alloys and the limitation of thinning of Co-Cr alloys are major obstacles, and the development of new magnetic layers has been hindered. was desired.

In addition, the present inventors have proposed a magnetic recording medium having a magnetic layer that has excellent corrosion resistance and does not impair reproduction output in Japanese Patent Application No. 156954/1982, in which a first magnetic layer mainly composed of CO and Ni is used. We proposed a structure in which a second magnetic layer mainly made of Co and Cr is laminated.

[Purpose of the invention]

An object of the present invention is to provide a magnetic recording medium having a magnetic layer that has even better corrosion resistance and does not impair reproduction output, and has magnetic properties as a second magnetic layer,
This paper proposes a magnetic recording medium using iron oxide as a material with higher corrosion resistance.

[Summary of the invention]

The present invention provides a magnetic recording medium in which a magnetic layer is formed by a thin film deposition method. It is characterized by consisting of a magnetic layer. As the thin film deposition method, a vacuum thermal deposition method, a sputtering method, an ion blating method, a plating method, etc. can be used. More specifically, in the present invention, a glass substrate or a non-magnetic total bending substrate is used.

For example, an NLP plating layer or an aluminum oxide layer is formed on an AQ composite alloy to form a smooth layer, and then an intermediate underlayer of Cr or the like is formed, and then a first magnetic layer and then a second magnetic layer are formed. A protective film is formed on the outermost layer.

The first magnetic layer is intended to suppress an increase in film thickness and to obtain a good reproduction output.

The second magnetic layer improves the corrosion resistance of the first magnetic layer, and has magnetism to improve spacing loss due to increase in film thickness. It is better for the second magnetic layer to be thin as long as it has corrosion resistance;
You can choose from a range of people.

The first magnetic layer containing cobalt as a component element is C
Consisting of o and Ni, Go and Ni further]? e
.

Added at least one element selected from P, W, Pt, and Cr, and furthermore, co, Pt, Y, La, and C.
e, Pr, S+m.

Examples include those consisting of at least one element selected from Nd and Pm. In the case of Co-Ni, Ni
A material containing 10 to 30 at% of carbon dioxide and having a thickness of not more than 2000 mm is used. Co--Ni to which a third element is added to improve electromagnetic conversion characteristics is superior in saturation magnetization or coercive force when a Bi-based magnetic layer is formed, which is the same as a Co--Ni magnetic layer. When Fe is used as the additive element, the saturation magnetization and squareness ratio are excellent. Furthermore, when the additive element is Pt, Su or P, the coercive force and squareness ratio are excellent. When the additive element is Cr, the coercive force can be increased and the corrosion resistance can be improved. Also C
o and Pt, Y, La, Ce, Pr, Sm.

At least one element selected from Nd and Pi is P t HY HL a HCe
t P r HSta 1 N d HP m is 5 to 4
It contains 0at% and is formed to a thickness of more than 2000 layers.

[Embodiments of the invention]

Example 1 Next, an example of the present invention will be described with reference to FIG. 1st
The figure is a partial cross-sectional view of the magnetic recording medium of the present invention.

In the 11th P+, 3.5 as the non-magnetic substrate (11)
A non-magnetic smooth layer (N1-P plated and mirror-polished) is used on one surface of an inch-inch aluminum alloy disk (
12) was formed. A magnetic layer, a protective layer, a lubricating layer, etc. were formed on this using a bipolar high-frequency sputtering device. The film forming method and film forming conditions are as follows. In order to make the film thickness and magnetic properties uniform, the substrate equipment stand can rotate around its axis.
The platform was rotated at 6 rpm. The initial vacuum level for film formation is 8.
．． At OX 10"" Torr.

Introduced Ar gas pressure 4. The sputtering was carried out at OX 10-" Torr, sputtering power 300 W, and room temperature. First, a base layer C13 was formed to improve the crystallinity of the magnetic layer.
), 2,500 Cr members were formed. On top of that, a first magnetic layer (15) of approximately 500 layers of Co-Ni and a second magnetic layer (16) of approximately 500 layers of Fe3O4 are formed, forming a two-layer magnetic layer (14). was configured. Furthermore, a protective/lubricating layer (17) made of a carbon film of 300 to 500 layers was provided on the outermost layer.

When the magnetic properties of the magnetic recording medium thus prepared were measured, an in-plane coercivity cuff of 00 oersted was obtained, and excellent results were also obtained regarding saturation magnetization and other magnetic properties.

Further, as a result of electromagnetic conversion characteristics, head wear tests, and environmental tests, the following characteristics were obtained. Regarding electromagnetic conversion characteristics, crystal density recording of 20 kbpi to 40 kbpi was possible. In the wear test with the head, we conducted a 20,000-time contact start/stop test, which is the standard practice, and confirmed that there were no scratches on the disk surface.

In addition, regarding environmental resistance, which is the key point of the present invention, after being left at a temperature of 85°C and a relative humidity of 85% for 1000 hours,
No changes in appearance were observed, no increase in defective areas, and sufficient corrosion resistance was confirmed.

Example 2 Similar to Example 1, an aluminum alloy nonmagnetic substrate (11
), and the surface was anodized to form alumina (A9
forming a nonmagnetic smooth layer (12) of a nonmetallic layer of
After that, as in the previous example, the non-magnetic metal underlayer nodes 1 and 2 are formed.
A magnetic layer and a protective/lubricant layer were formed. In this example as well, the same effects as in Example 1 were obtained.

Example 3 Ni was used as the first magnetic layer (15) of Example 1 at 17at.
%.

With a composition of 8 at% Fe and other Co, Co-Ni-
When we created a material with about 700 Fe layers, we obtained an in-plane coercive cuff of 50 oersteds, and the electromagnetic conversion characteristics were the same as Co-Ni at a reduced output of 1°OmV, and the linear recording density was improved by about 10%. The durability and environmental resistance were as good as in Example 1.

Example 4 Sm was 16 as the first magnetic JPJ (15) of Example 1.
When 700 pieces of Co-5m containing at% were prepared, an in-plane coercive force of 800 oersted was obtained, and it was found that the electromagnetic conversion characteristics, durability, and environmental resistance were as good as Example 1.

〔Effect of the invention〕

As described above, according to the present invention, by providing two magnetic layers having different functions, it is possible to provide a magnetic recording medium that has excellent corrosion resistance and can be made thinner for higher density.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a magnetic recording medium according to an embodiment of the present invention, and FIG. 2 is a partial sectional view 1-1 of a conventional magnetic recording medium. (11)...Nonmagnetic substrate, (12)...Nonmagnetic smooth layer, (13)...Nonmagnetic metal base layer, (■4)
magnetic flux, (15)...first magnetic layer, (1
6)...Second magnetic layer, (17)...Protection/lubrication"
jri. Agent Patent Attorney Noriyuki Chika Yudo Daiko Norio Figure 2

Claims (1)

[Claims] A magnetic recording medium having a first magnetic layer containing cobalt as a component element and a second magnetic layer containing iron oxide as a main component on a nonmagnetic substrate.