JPS5988807A - Magnetic storage body - Google Patents

Abstract

PURPOSE:To obtain a magnetic storage body having a metal thin film medium which excels in corrosion proof property by providing the specified alloy thin film layer on non-magnetic metal layer or non-magnetic metal oxide layer formed on a metal disk. CONSTITUTION:A metal disk 1 made of aluminum alloy is covered with non- magnetic metal layer or non-magnetic metal oxide layer, for example, a nickel- phorphorus alloy or aluminum oxide alloy layer. Moreover, an alloy consisting of panadium, platinum and cobalt or an alloy consisting of tungsten, platinum and cobalt is provided thereon as an alloy thin film medium 3. Next, the alloy thin film medium 3 is covered with a protection film 4 made of SiO2 etc. Thereby, a magnetic storage body having a metal thin film medium which excels in corrosion proof property can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic storage body used in a magnetic storage device (magnetic disk device, magnetic drum device, etc.).

Most of the magnetic storage bodies currently in practical use have discontinuous media. This discontinuous medium magnetic storage medium is
r-kT'0□03. Magnetic particles such as CrO, Fe, Fe-Co, etc. are mixed in a binder made of an all-organic resin, coated on a substrate, dried, and fired. It is discontinuous at the level of magnitude.

However, in recent years, due to the demand for higher recording densities in magnetic storage media, research and development of magnetic storage media consisting of continuous thin film media has been actively conducted. This continuous thin film medium mainly consists of metal thin films made by methods such as plating, vacuum evaporation, sputtering, and ion blating;
Magnetic recording media made of metal oxide thin films such as e304 or r-Fe2O2 made by sputtering, ion blating, etc. are known. Magnetic recording media made of metal thin films (hereinafter referred to as metal thin film media) are used at high temperatures, It is easy to corrode in a poor atmosphere such as a high humidity environment, and a metal thin film medium with sufficient corrosion resistance is not yet known.

SUMMARY OF THE INVENTION In view of the above-mentioned current situation, an object of the present invention is to provide a magnetic memory having a metal thin film medium having excellent magnetic properties and extremely excellent corrosion resistance.

That is, in the magnetic memory of the present invention, a nonmagnetic metal layer or a nonmagnetic metal oxide layer is cut out on a metal disk, and an alloy consisting of vanadium, platinum, and cobalt or A metal thin film medium made of an alloy of tungsten, platinum, and cobalt is coated, and a protective film is coated on the medium.

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partial cross-sectional view of the magnetic storage body of the present invention.

In FIG. 1, metal disks 1 and 1 of the magnetic memory are most often made of aluminum alloy because they are light, easy to work with, and inexpensive, but titanium alloy may be used in some cases. The surface of the base is machined into a surface with small undulations (less than 50 m in the circumferential direction and less than 100 m in the radial direction).

Next, a non-magnetic metal layer 2 of nickel-alloy or aluminum oxide is plated on top of this base 1, and the surface of this base 2 is mechanically polished to a maximum surface roughness of 0.03.
Mirror finish to less than m.

Next, a metal thin film medium made of vanadium or cobalt containing tungsten and platinum is coated as a metal magnetic medium 3 on the mirror-polished surface of the base body 2 by a high frequency sputter method. Next, on the metal thin film medium 3, a film typified by SiO is placed. A film 4 is applied by high frequency sputtering.

Metal thin film media has coercive force (Ha) 5'00~1200Q
Rusted on θ), saturation magnetic flux density (B8) 10,0OO
G (glass) Squareness ratio (8%8) 0.7 to 0.9
A magnetic recording medium with a coercive force squareness ratio (S*) of 0.7 to 09 and a coercive force squareness ratio of 1 to 1 exhibits excellent hysteresis characteristics. The above characteristics indicate the change in gold initial thin film and squareness depending on the atomic percentage of vanadium or tungsten in the metal thin film medium, and vanadium or tungsten is 1 to 3, respectively.
It can be used as a magnetic storage medium capable of daytime recording density in the range of Qat, %, or 1 to 2 Qat.

As described above, it can be seen that a metal thin film made of a cobalt alloy containing platinum and vanadium containing 30 atomic percent or less or 20 atomic percent or less of tungsten in total is excellent as a magnetic recording medium.

The protective film coated on the metal thin film medium 3 is preferably hard, and is made of metals such as osmium, ruthenium, 5-iridium, manganese, and tungsten, or oxides of silicon, titanium, tantalum, or hafnium,
A silicide or carbide, boron, carbon, an alloy of boron and carbon, or polysilicic acid is preferable. Kefluorinated hydrocarbon Gkecoo
pr, OHNH2, coof, Sl < 017”
)3, a functional group such as CONH2) or a lubricant such as fluorinated alkyl polyether or polytetra-70-roethylene telomer can be completely coated.

Next, the present invention will be explained with reference to some examples.

Example 1 A non-magnetic alloy 2 was placed on a disc-shaped aluminum alloy disc that had been finished with sufficiently small waviness (50 m or less in the circular direction and 10 rn or less in the radial direction) by lathe processing and thermal straightening as the alloy disc 1. Nickel-phosphorus alloy is plated to a thickness of approximately 50 m, and this nickel-phosphorus plating film has a maximum surface roughness of 0.02 m and a thickness of 30 m.
Finished with mirror polish.

6- Next, a metal magnetic medium 3 is formed on this nickel-phosphorus plating film by high-frequency sputtering at an argon pressure of 4×10
film thickness at torr, power density I W/crI: 511
Full coating of cobalt alloy thin film containing 9 atomic percent vanadium and 20 atomic percent total platinum in OA 1. Ta.

Furthermore, 5ifl, f 20 on top of this metal magnetic medium 3
A magnetic disk was fabricated by coating the OA film with a high frequency sputtering method. Coercive force HC, residual magnetic flux density 13r, *squareness S and coercive force squareness S 9600θ, respectively.
It was 6500G, 0.85.0.85.

Example 2 A magnetic disk was fabricated in the same manner as in Example 1, except that the metal magnetic medium 3 was coated with a cobalt alloy thin film containing 6 atomic percent of tungsten and 32 atomic percent of platinum to a thickness of 5 mm. ) lc, Br, S and ? were 9500111.4500GXO, 8, and OB, respectively.

Example 3 A magnetic disk was fabricated in the same manner as in Example 1 except that the metal magnetic medium 3 was coated with a cobalt alloy thin film containing 3 atomic percent of tungsten and 32 atomic percent of platinum to a thickness of 50X.

Ha, BrX5XS* are respectively 12000s and 5
'1OO (Es O, 85,085.

Example 4 A magnetic disk was fabricated in the same manner as in Example 1, except that the metal magnetic medium 3 was coated with a cobalt alloy thin film containing 2 atomic percent vanadium and 20 atomic percent total platinum to a thickness of 300×. HQ, Br, SXS
are 11000θ, 9600G, and 0.85.0 respectively.
It was 85.

Example 5 A magnetic disk was fabricated in the same manner as in Example 1, except that the metal magnetic medium 3 was coated with a cobalt alloy thin film containing 10 atomic percent of tungsten and 32 atomic percent of platinum 1 to a film thickness of tsoof. He, 13r, S.

S is 60000.3200G and 0.80.0 respectively
．． Example 6 A magnetic disk was prepared in the same manner as in Example 1, except that the metal magnetic medium 3 was coated with a cobalt alloy thin film containing 13 atomic percent of vanadium and 20 atomic percent of total platinum to a thickness of 800 Å. He, nr, s, and E” were c+oooc, 5000G, and 0.85.0.85, respectively.

Example 7 A magnetic disk was fabricated in the same manner as in Example 1, except that as the metal magnetic medium 3, a cobalt alloy thin film containing tungsten'+1-10 atomic percent and platinum at 20 atomic percent was coated with a film thickness of 2 (lnOA) IC. ,Br,S,? are 8000e, 3200G, 0.80.0.8 respectively
0f atse.

Example 8 A magnetic disk was fabricated in the same manner as in Example 1, except that metal magnetic media 3 and 1- were coated with a cobalt alloy thin film containing 25 atomic percent vanadium and 20 atomic percent platinum to a thickness of 500 A'. I (a, Br, S, d' are respectively 7000θ, 2000G, 0.80.0.80
Met.

Example 9 A magnetic disk was fabricated in the same manner as in Example 1, except that the metal magnetic medium 3 was coated with a cobalt alloy thin film containing 15 atomic percent of tungsten and 20 atomic percent of platinum at a film thickness of s O (l A.HQ). ,, 13r, &
S* is 5500θ, 2000α0.80.0, respectively.
80 Example 10 Same as Example 1 except that the argon pressure was 4×10 torr.
, a magnetic disk was made at a power density of 15 W//ctl.

Example 11 Same as Example 1 except that the argon pressure was 8×10 torr.
A magnetic disk was manufactured at a power density of 15 W/i.

Example 12 Same as Example 2 except that the argon pressure was 4 x 10 torr.
.

A magnetic disk was made at a power density of 15 W/i.

Example 13 Same as Example 2 except that the argon pressure was 8 x 10 tOrr.
.

A magnetic disk was made at a power density of 1 sW/i.

Example 14 In the same manner as in Example 1 or 2, except that the surface of the aluminum alloy disk 1 was coated with aluminum oxide f by anodic oxidation as a non-magnetic alloy layer and a non-magnetic metal oxide layer 1 to 1, and this aluminum oxide was coated with the maximum surface roughness. A magnetic disk was produced by mirror polishing to 0.02 +n.

Example 15 Same as Example 1 or 2, but as a protective film, all of the following materials were sputtered to a thickness of 5ooA Comparative Example 1 Same as Example 1, but a film thickness of 1 was formed on the nickel-phosphorus plating film. The entire magnetic disk was fabricated by coating cobalt as a metal magnetic medium 3 with a film thickness of 5OOX through chromium of m.

Coercive force HQS residual magnetic flux density Br, squareness S, coercive force squareness? are respectively 6000θ and 136000108.08
Met.

Comparative Example 2 In the same manner as in Example 1, a magnetic disk was entirely coated with a cobalt alloy thin film consisting of 35 att of platinum and the balance of cobalt to a film thickness of 500 %. Coercive force HC, residual magnetic flux density B
r, squareness S, coercive force squareness s% each 8000θ,
It was 11000 G, 0.80.0.80.

Using the magnetic disks shown in Examples 1 to 15 and Comparative Example 1.2, we conducted electromagnetic conversion characteristics, friction tests, environmental tests, and water immersion metal corrosion tests.
The following properties were obtained. Example 1 regarding electromagnetic conversion characteristics
15 disks 1 (40.000~80.0 (I
A recording density of OFRPI was obtained, but only a recording density of U 20,000 FRPI was obtained with the disk of Comparative Example 1.2. As for the wear test with the head, no scratches were observed on the disk surface after 20,000 contact start-stop tests were performed. In addition, all the environmental tests were carried out in which the temperature was 80°C and the relative humidity was 90% for 6 months.'') For Examples 1 to 15 and Comparative Example 2, the increase in the number of errors was 0, but for the Comparative Example The error of the disc No. 1 increased by 100 times (-).Finally, the discs of Examples 1 to 15 and Comparative Example 1.2 were cut and 15 ran
When all sections of 15 mm were made and immersed in 2 IC water for one month and changes in the saturation magnetic flux density Bll were investigated, the results shown in Figure 4 were obtained. Figure 4 shows the rate of change (8%
. , BO indicates the time change of saturation magnetic flux density before immersion)1-
The closer the value is to 10, the better the corrosion resistance. Suno,
In other words, in Examples 1 to 15, even after being immersed in water for one month, there was no change in the ratio at all, but Comparative Example 1 showed 50% change, Comparative Example 2
% HB decreased. From the results above, it was found that the magnetic memory of the present invention has excellent corrosion resistance (environmental resistance), wear resistance, and high recording density characteristics.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of an embodiment of the magnetic storage body of the present invention. In the figure, 1 is a base plate, 2 is a nonmagnetic alloy layer, 3 is a metal thin film medium, and 4 is a protective film. Figures 2 and 3 show the saturation magnetic flux density, coercive force, and characteristics of the metal thin film medium used in this magnetic storage body, as well as changes depending on the atomic percentage of vanadium or tungsten in the rectangular metal thin film medium. figure. Figure 4 is a characteristic diagram showing the rate of change in saturation magnetic flux density depending on the water immersion time of the metal thin film medium used in this magnetic storage body. 14- Content (αt, %) in Figure 1 and Figure 2 3. Take note of the p wave

Claims (1)

[Scope of Claims] 1. A metal disk is coated with a non-magnetic metal layer or a non-magnetic metal oxide layer, and an alloy consisting of vanadium, platinum and cobalt or tungsten is coated on the non-magnetic gold maple or non-magnetic metal oxide layer. An alloy thin film medium of an alloy consisting of platinum and cobalt is coated, and a # retaining film is coated on the alloy thin film medium.
2. A magnetic memory body according to claim 1, wherein the nonmagnetic metal layer is nickel-phosphorous. 3. A nonmagnetic oxide I- The magnetic memory body according to claim 1, wherein the material is fermented aluminum. 4. Protective film: osmium, ruthenium, iridium,
Claims ml which are manganese and tungsten! J
The magnetic storage body according to l. 5. The magnetic memory according to claim 1, wherein the protective film is an oxide, nitride or carbide of silicon, titanium, tantalum or hafnium. 6. The magnetic memory body according to claim 1, in which the protective film is made of boron, carbon, or an alloy of boron and carbon. 7. The magnetic memory body according to claim 1, in which the protective film is made of polysilicate.