JPH0215922B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a magnetic storage body used in a magnetic storage device (such as a magnetic disk device or a magnetic drum device).

In general, there are the following methods for recording and reproducing a magnetic storage device comprising a recording and reproducing magnetic head (hereinafter referred to as a head) and a magnetic storage body. That is, after the head and the magnetic storage surface are set in contact at the start of operation, a space corresponding to an air layer is created between the head and the magnetic storage surface by giving the magnetic storage the required rotation, and this This is a method of recording and reproducing in the current state (contact start-stop method, hereinafter referred to as CSS method). In this method, at the end of the operation, the magnetic storage body stops rotating, and at this time the head and the magnetic storage body surface are in a frictional state of contact, as at the beginning of the operation.

The frictional force generated between the head and the magnetic storage material under these contact friction conditions can wear out the head and the magnetic storage material and may eventually cause scratches on the head and the metal magnetic medium. Further, in the contact friction state, a slight change in the posture of the head may cause the load applied to the head to become uneven, causing scratches on the surface of the head and the magnetic storage body.

Furthermore, during recording and reproducing, the head suddenly comes into contact with the magnetic storage body, and a large frictional force acts between the head and the magnetic storage body, often resulting in destruction of the head and the magnetic storage body. In order to protect the head and the magnetic memory from such contact friction, contact wear and contact breakage between the head and the magnetic memory, it is necessary to coat the surface of the magnetic memory with a protective film.

A variety of protective films have been proposed in the past, and one of them is a 200% protective film that has been chemically treated on the surface of a metal magnetic medium used as a storage medium in a magnetic storage body.
A method is known in which a protective film made of metal oxide is formed by firing at a temperature of ~290°C (Japanese Patent Publication No. 49
(Refer to Publication No.-29445 and Japanese Patent Publication No. 50-30443).

However, with this method, local corrosion of the metal magnetic medium occurs due to chemical conversion treatment, and since it is fired at a high temperature, cracks or warpage occur in each coating layer that constitutes the magnetic storage body due to differences in thermal expansion coefficients.
One of the coating layers, nickel-phosphorus, is magnetized. Moreover, it often impairs the magnetic properties of the metal magnetic medium.

Yet another method is to coat a non-magnetic nickel or cobalt alloy on a metal magnetic medium and electrochemically oxidize the surface (Japanese Patent Application Laid-Open No.
(See Publication No. 52-80804). However, electrochemically formed metal oxides are metal hydroxides or hydrated metal oxides, which have weaker strength and lower corrosion resistance than anhydrous metal oxides made by high-temperature oxidation. be.

An object of the present invention is to provide a method for manufacturing a magnetic memory body which does not cause the above-mentioned disadvantages associated with high-temperature firing, and which is formed using an anhydrous metal oxide as a protective film, which has high strength and excellent corrosion resistance. be.

That is, the present invention is characterized in that a metal magnetic medium is coated on a base body having a mirror surface, and the surface of the medium or another metal coated thereon is irradiated with laser light to form a metal oxide. It is said that
Metals coated on the surface to form metal oxides include Co, Ni, Fe, Cr, Al, Cu, Zr,
Ti, Ag, Ni-P, Co-Ni-P, Co-Cr, Co-
Examples include alloys of B, Ni-Sn-P, N-W, Ni-B, or a combination thereof.

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

1 and 2 are partial cross-sectional views of the magnetic storage body.
In FIG. 1, aluminum alloy is most often used as the base 1 of the magnetic memory body because it is light, easy to work with, and inexpensive, but titanium alloy may also be used in some cases. The base surface is finished by machining into a surface with small undulations (50 μm or less in the circumferential direction and 100 μm or less in the radial direction).

Next, a nickel-phosphorus alloy is coated on this base 1 as a base body 2 by plating, and this base body 2
The surface has a surface roughness of 0.03μm by mechanical polishing.
Mirror finish is achieved below (Rmax).

Next, a cobalt-nickel-phosphorus alloy is coated on the mirror-polished base body 2 as a metal magnetic medium 3 by plating.

Next, a laser beam 6 is applied to the surface of the metal magnetic medium 3.
By irradiating the medium 3 with , the surface of the medium 3 is converted into a metal oxide 4 and a protective film is formed.

Further, in FIG. 2, a metal film 5 is coated on the metal magnetic medium 3, and then the surface of the metal film 5 is irradiated with a laser beam 6.
All or the surface thereof is converted into metal oxide 41 to form a protective film.

In the case of Fig. 1, the oxidation of the metal magnetic medium 3 is from 0.05 to
Although it is necessary that only 0.10 μm remain, in the case of FIG. 2, the metal film 5 may be completely oxidized.

Formation of a metal oxide by laser light according to the present invention involves magnetizing the nickel-phosphorus alloy used as the base body 2, or by magnetizing the nickel-phosphorus alloy used as the base body 2, or by magnetizing the nickel-phosphorus alloy used as the base body 2, in addition to thermal baking and thermosetting by the absorption of laser light by the metal oxide. One of its excellent features is that it does not cause cracks, peeling, or warping due to differences in thermal expansion coefficients.

In other words, the high energy density of laser light and
Due to the high laser light absorption of metal oxides and the high laser light reflectance of metals, a high temperature gradient is created between the metal oxide and the substrate, which causes thermal sintering and thermal curing of the metal oxide and simultaneous thermal curing of the substrate. This has the dual effect of preventing magnetization, crack warping, and peeling.

Furthermore, the oxidation rate of the metal can be increased by performing the step of irradiating the metal surface with laser light in an oxidizing atmosphere such as oxygen or ozone. That is, while metal surfaces reflect laser light very well, metal oxides absorb laser light well, so by irradiating the metal surface with laser light in an oxidizing atmosphere, the formation of metal oxides progresses rapidly.

Next, the present invention will be explained in detail with reference to Examples and Comparative Examples.

Example 1 As the substrate 1, a disc-shaped aluminum alloy plate whose surface was finished with sufficiently small waviness (50 μm or less in the circumferential direction and 10 μm or less in the radial direction) by lathe machining and heat straightening was used as the base body 2. Nickel-phosphorus alloy is plated to a thickness of approximately 50μm, and this nickel-phosphorus plating film has a surface roughness of 0.02μm.
Mirror polished to a thickness of 30 μm. Next, a cobalt-nickel-phosphorus alloy was plated on the nickel-phosphorus plating film to a thickness of 0.15 μm as a metal magnetic medium 3.

Next, a disk-shaped disk coated with cobalt-nickel-phosphorus alloy is rotated at 200 rpm and output.
A 250W continuous wave carbon dioxide laser with a beam diameter of 0.15mm is irradiated in the radial direction at a speed of 20mm per minute onto a cobalt-nickel phosphorus alloy surface in air.
A magnetic disk was made by forming an oxide of the cobalt-nickel-phosphorus alloy on the surface of the alloy.

Example 2 A magnetic disk was manufactured in the same manner as in Example 1, except that a pulsed carbon dioxide laser of 50 MW and a beam diameter of 30 mm was used as the laser light source.

Example 3 A magnetic disk was manufactured in the same manner as in Example 1, except that a pulse oscillation ruby laser of 100 MW and a beam diameter of 40 mm was used as the laser light source.

Example 4 Same as Example 1, except that pulse oscillation YAG with 10 MW and beam diameter of 10 mm was used as the laser light source.
Created a magnetic disk using a laser.

Example 5 A magnetic disk was produced in the same manner as in Example 1, except that laser irradiation was performed in an oxygen atmosphere.

Example 6 A magnetic disk was produced in the same manner as in Example 3, except that laser irradiation was performed in an ozone atmosphere.

Example 7 Same as Example 1, except that metal magnetic medium 3
A magnetic disk was made using a cobalt-chromium alloy coating.

Example 8 A magnetic disk was produced in the same manner as in Example 7, except that a pulsed ruby laser with a power density of 6.3×10 ⁶ W/cm ² was used as the laser light source and irradiation was performed for 10 μs in an oxygen atmosphere.

Example 9 Same as Example 7, except that pulse oscillation YAG with a power density of 1×10 ⁷ W/cm ² was used as the laser light source.
A magnetic disk was fabricated using a laser for 50 μs irradiation in an ozone atmosphere.

Example 10 Same as Example 1, except that metal magnetic medium 3
A cobalt-nickel-phosphorus alloy was plated to a thickness of 0.05 .mu.m as a metal film 5, and a nickel-phosphorus alloy was plated thereon to a thickness of 0.05 .mu.m.

Next, the power density is applied to the surface of the nickel-phosphorus alloy.
A 1.4×10 ⁶ W/cm ² continuous wave carbon dioxide laser was irradiated in the air for 4 ms to form a nickel-phosphorus alloy oxide to produce a magnetic disk.

Example 11 A magnetic disk was produced in the same manner as in Example 10, except that laser irradiation was performed in an oxygen atmosphere.

Example 12 A magnetic disk was produced in the same manner as in Example 10, except that a pulsed ruby laser with a power density of 6.3×10 ⁶ W/cm ² was used as the laser light source and laser irradiation was performed in an ozone atmosphere.

Example 13 Same as Example 10, except that as the metal film 5
A magnetic disk was made using Cr plated to a thickness of 0.1 μm.

Example 14 A magnetic disk was fabricated in the same manner as in Example 10, except that the metal film 5 was coated with aluminum to a thickness of 0.05 μm.

Example 15 A magnetic disk was fabricated in the same manner as in Example 10, except that the metal film 5 was coated with zirconium to a thickness of 0.10 μm.

Example 16 A magnetic disk was fabricated in the same manner as in Example 10, except that the metal film 5 was coated with titanium to a thickness of 0.10 μm.

Example 17 A magnetic disk was fabricated in the same manner as in Example 10, except that the metal film 5 was plated with copper to a thickness of 0.10 μm.

Comparative Example 1 A disk-shaped disk coated with a cobalt-nickel-phosphorus alloy as a metal magnetic medium prepared in the same manner as in Example 1 was immersed for 2 minutes in an aqueous solution containing 2 g of nitric acid and 20 g of trisodium citrate. After that, it was washed with water, dried, and then heated in air at 250°C for 2 hours to make a magnetic disk.

Comparative Example 2 A disk-shaped disk coated with a cobalt-nickel-phosphorus alloy as a metal magnetic medium produced in the same manner as in Example 1 was fired and heated in air at 275° C. for 2 hours to produce a magnetic disk.

Comparative Example 3 A disk-shaped disk coated with a cobalt-nickel-phosphorus alloy was coated with a cobalt-nickel-phosphorus alloy as a metal magnetic medium prepared in the same manner as in Example 1.The disk-shaped disk was coated with a nickel-phosphorus alloy by plating, and the entire disc was immersed in a 10% sulfuric acid solution. Then, the surface of the nickel-phosphorus alloy was electrochemically oxidized under the following conditions.

Anode: disk-shaped disk, cathode: stainless steel plate Temperature: room temperature Anode current density: 1.5 to 5.5 A/ ^dm 2Anhydrous metal oxide formed on the surface of each magnetic disk shown in Examples 1 to 17 and Comparative Examples 1 to 3 The strength of the material or hydrated metal oxide was measured by a scratch test using a 0.03R sapphire needle. In Comparative Examples 1, 2, and 3, the strength was measured at a load of 30 g, 40 g, and 10 g.
Scratches occurred on the surface at 60 g in Examples 1 to 9.
In Examples 10-17, no scratches occurred up to 60-80 g.

Furthermore, using the magnetic disks of Examples 1 to 17, CSS
The method was tested 10,000 times and no scratches appeared. On the other hand, head crash occurred in the magnetic disks of Comparative Examples 1 and 2 after about 5000 CSS cycles, and in Comparative Example 3 after about 500 CSS cycles.

In addition, when the magnetic properties of each magnetic disk were investigated, there was no change in the magnetic properties of the magnetic disks of Examples 1 to 17, but the magnetic disks of Comparative Examples 1 and 2 had nickel-phosphorus used as the base material, which was magnetized. The output voltage from the head was reduced by 50%.

In addition, when a humidity test was conducted for 120 hours at a humidity of 80% and a temperature of 40°C, the dropout increased by about 50 times, 10 times, and 50 times in Comparative Examples 1, 2, and 3, respectively, but in Examples 1 to 17, the dropout Almost no increase was observed in disks.

From the above, it was found that the magnetic disk manufactured by the method for manufacturing a magnetic storage body of the present invention has superior reliability.

[Brief explanation of drawings]

FIGS. 1 and 2 are partial cross-sectional views showing magnetic storage bodies manufactured according to the present invention, respectively. 1 is a base, 2 is a base body, 3 is a metal magnetic medium, 4
is a metal oxide, 5 is a metal film, and 6 is a laser beam.

Claims (1)

[Claims] 1. A magnetic storage body having a metal surface, which is characterized in that the surface thereof is irradiated with laser light in an oxidizing atmosphere to provide a protective film made of an oxide of the surface metal. manufacturing method. 2 The metal is Co, Ni, Fe, Cr, Al, Cu, Zr, Ti,
Ag, Ni-P, Co-P, Co-Ni-P, Co-Cr,
2. The method for manufacturing a magnetic memory body according to claim 1, wherein the material is an alloy of Co-W, Co-B, Ni-Sn-P, Ni-W, Ni-B, or a combination thereof.