JP3181643B2 - Magnetic recording medium and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium for performing digital and / or analog magnetic recording, comprising a thin plate-like magnetic material having magnetic anisotropy in the plane direction of a thin plate, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, electronic information devices centering on computers have been developed, and magnetic recording devices as external recording devices for information have been required to have a large capacity, small size, and stable information storage, and have been put into practical use. There are a hard disk device in which a disk-shaped recording medium is placed in an airtight drive, and a flexible disk device in which the medium can be easily exchanged.

[0003] The magnetic recording medium used in these magnetic recording devices is prepared by applying a magnetic powder to the surface of a non-magnetic substrate such as a resin film, aluminum, or glass.
It is manufactured by plating or sputtering a magnetic material. The thickness of the magnetic layer responsible for magnetic recording is several μm when applied, and several tens nm when sputtered.

In any of the methods for manufacturing a magnetic recording medium, the surface of the substrate is required to have a surface roughness adjusted with high precision, and the magnetic layer is formed under strictly controlled conditions.

[0005] Magnetic cards such as cash cards, credit cards, and prepaid cards are magnetic recording media for magnetically recording a personal identification number, a balance, and the like on a magnetic layer applied to the card. Since the recording density of the magnetic recording layer of each card is low, only the minimum information is recorded.
Much of the information is stored in a central storage device, and operations such as withdrawal and settlement are performed by a terminal that handles cards while referencing the information to the center.

[0006]

The magnetic recording medium manufactured by the above-mentioned method is expensive when a magnetic layer for performing magnetic recording is formed, such as a magnetic material coating apparatus or an in-line type sputtering apparatus. Equipment is required and is a major source of increased manufacturing costs.

On the other hand, these conventional magnetic recording media have a disadvantage that the magnetic layer is easily damaged because the thickness of the magnetic layer is extremely thin, several tens nm to several μm.

The magnetic recording medium used in the flexible disk drive is manufactured on the assumption that the recording / reproducing head and the recording medium are used in contact with each other.
Although the durability against external mechanical action such as scratching may be said to be high, the magnetic recording density is low because a discontinuous magnetic layer made of magnetic powder or the like is used as a recording medium.

The magnetic recording medium of the hard disk drive uses a non-contact type flying head because the medium is fixedly used in the apparatus. The contact between the head and the medium causes breakage immediately and causes an irreparable state. Further, since the gap between the head and the medium is several thousand angstroms, it is necessary to maintain an atmosphere free from dust and the like having a size larger than this size.

On the other hand, the magnetic card takes the form of being carried by the user himself to the terminal and is handled relatively sloppyly. Therefore, the magnetic recording medium for recording information has a structure that emphasizes durability. The magnetic layer is formed by applying an oxide magnetic material kneaded with a binder to a thickness of several μm on a resin card, and a thick protective layer of about 100 μm is formed thereon.

Therefore, the magnetic card has a gap corresponding to the protective layer between the magnetic head for recording and reproducing and the magnetic layer.
Since high-density magnetic recording cannot be performed, only limited information such as a password and a balance is recorded.

The present invention provides a magnetic recording medium for remedying the above-mentioned disadvantages of the prior art, and can be manufactured by a simple method using a magnetic thin plate itself as a magnetic recording medium.
In addition, it has a feature of high recording density and robustness.

[0013]

In order to achieve the above object, a magnetic recording medium according to the present invention comprises cobalt 5-2.
5% by weight, 15 to 35% by weight of chromium, and the balance iron as an essential component, and one or more elements of one or more of titanium, vanadium, niobium, molybdenum, tungsten, tantalum, zirconium, silicon, and aluminum.
005 to 10% by weight of an alloy containing
A thin plate of 0.5 to 3 mm, the thin plate is magnetically a the magnetic anisotropy in one direction in the plate surface, and magnetic recording of the thin plate
By finishing the surface roughness of the flat surface
It is characterized in that is 1/10 or less of the recording wavelength Ri.

According to the present invention, there is also provided a method of melting a mixture or alloy having the above-mentioned composition, casting it into an ingot, subjecting the obtained ingot to a solution treatment, and then casting.
Next, after performing cold rolling and / or hot rolling to obtain a thin plate, the obtained thin plate is subjected to an aging treatment while applying a magnetic field in a parallel direction, and then the surface roughness of a flat portion serving as a magnetic recording surface of the thin plate is obtained. And the thickness of the thin plate is 0.5 to
This is a method for manufacturing a magnetic recording medium, characterized in that a finishing process is performed on 3 mm.

The magnetic recording medium of the present invention having the above configuration is usually used by being formed on a so-called magnetic disk of a thin disk having a diameter of 0.5 to 8 inches or a rectangular magnetic card having a side of several tens of mm. .

In the case of a magnetic disk, information is recorded on concentric circles by rotating a magnetic recording medium and moving a magnetic head in the diameter direction. In the case of a magnetic card, information is recorded while the magnetic head is moved linearly on the card.

The medium responsible for magnetic recording is the thin plate itself of the magnetic recording medium, which is a continuous magnetic material. Therefore, the magnetic recording density is equivalent to that of a conventional hard disk, and since a limited thin magnetic layer is not used as a recording medium, high durability against contact or collision between the head and the magnetic material and mechanical action from the outside is achieved. Have.

The magnetic material constituting the magnetic recording medium of the present invention is magnetically anisotropic in the in-plane direction, and the magnetic recording can be magnetized in a direction parallel to the plane of the thin plate. Therefore, the magnetic recording medium of the present invention is compatible with the conventional longitudinal recording method,
Further, since magnetic recording is performed in the anisotropic direction, the magnetic property in the recording direction is higher than that in the case where an isotropic medium is used, which is suitable for high density magnetic recording.

Here, in manufacturing the magnetic recording medium of the present invention, it is necessary that the above-mentioned magnetic material can be easily manufactured in a thin plate shape.

The magnetic material serving as the magnetic recording medium of the present invention is composed of iron, cobalt and chromium as main constituent elements. It is a material that can be subjected to plastic deformation and cutting. This is a great advantage in the manufacture of magnetic recording media, and magnetic materials that can be used for general magnetic recording and that show hard or semi-hard magnetism are a significant manufacturing advantage over those manufactured by casting or powder metallurgy. This is a cost advantage.
Magnetic properties are 8-13kG in residual magnetic flux density with anisotropic material,
It has a coercive force of 400 to 700 Oe and exhibits excellent characteristics as a magnetic recording medium. It is generally clear that there is no magnetic material other than the magnetic material that constitutes the present invention that can perform plastic deformation processing and cutting while exhibiting such excellent magnetic properties.

[0021]

Next, the present invention will be specifically described based on embodiments.

Example 1 10% by weight of cobalt, 24% by weight of chromium, 1.0% by weight of vanadium, 0.5% by weight of titanium, 0.5% by weight of niobium, 0.1% of silicon.
An ingot consisting of 2% by weight, 0.1% by weight of aluminum and the balance of iron was produced by vacuum induction melting, then cast into a predetermined shape, and then subjected to cold rolling to obtain a steel sheet having a thickness of 1.2 mm. In an argon gas atmosphere at a temperature of 1,100 ° C1
The solution treatment was performed under the condition of keeping time. Next, after performing a straightening process to make a flat steel plate, a diameter of 7
It was a 6.2 mm (3 inch) disk with a 7.8 mm diameter hole in the center in the same way. Next, the disk was rotated at 200 rpm in a heat treatment furnace, and held at 625 ° C. for 1.5 hours while applying a magnetic field of 2,000 Oe in parallel to the surface.
2 hours at 580 ° C, 4 hours at 560 ° C, 4 hours at 540 ° C,
A multi-stage aging treatment was performed at 500 ° C. for 6 hours.

In the obtained disk-shaped magnetic material, a hole at the center was polished to 8 mm, and a flat surface serving as a magnetic recording surface was polished to a surface roughness of 0.05 μm.

The magnetic properties of the disk-shaped magnet thus produced show a residual magnetic flux density of 12.2 kG and a coercive force of 600 Oe in the circumferential direction, and a residual magnetic flux density of 6.4 kG and a coercive force of 380 Oe in the other directions. Anisotropy is provided.

The produced magnetic recording medium is fixed to a rotating shaft of a hard disk drive, and the number of rotations is
When recording and reproduction were performed at 3,000 rpm and a recording frequency of 9.4 MHz, a reproduced signal waveform corresponding to the recording frequency was obtained. The recording track was set at every 8 μm. This is the linear recording density
60 kfci (kilo flux change per inch), equivalent to 3,100 TPI. When 1 fc is 1 bit, the magnetic recording medium is 75 Mbyt on one side of a 3 inch disk.
e corresponds to the recording capacity of e.

Example 2 An ingot composed of 12% by weight of cobalt, 26% by weight of chromium, 1.5% by weight of molybdenum, 0.5% by weight of tungsten, 0.5% by weight of tantalum, 0.5% by weight of zirconium, 0.2% by weight of titanium and the balance of iron was vacuum-high-frequency After being produced by a melting method, and then cast into a predetermined shape, cold rolling is performed to obtain a steel sheet having a thickness of 0.5 mm, and the steel sheet is heated in an argon gas atmosphere at a temperature of 1,100.
The solution treatment was performed at a temperature of 1 ° C. for one hour. Then
After performing a straightening process to form a flat steel sheet, the sheet was cut into a card having a size of 85 × 54 mm. Next, the card was kept in a heat treatment furnace at 620 ° C. for 2 hours while applying a magnetic field of 2,000 Oe in the longitudinal direction of the card, and further from 0.1 ° C. to 500 ° C. for 0.1 hour.
Aging treatment by continuous cooling was performed at a cooling rate of 2 ° C / min.

The magnetic characteristics of the magnetic card show a residual magnetic flux density of 13 kG and a coercive force of 680 Oe in the longitudinal direction, a residual magnetic flux density of 5.2 kG and a coercive force of 200 Oe in other directions, and a magnetic anomaly is given in the longitudinal direction of the card. ing.

The flat surface serving as the magnetic recording surface was polished to a surface roughness of 0.05 μm.

The contact type magnetic head was recorded at a speed of 0.5 m / s and a frequency of 1 MHz in the longitudinal direction of the surface of the manufactured magnetic card.
Upon reproduction, a reproduced signal waveform corresponding to the recording frequency was obtained. The recording / reproducing tracks were every 2 mm. This is because when the linear recording density is 36 kfci (kilo flux change per inch), and the entire area of one side of the card is used as a magnetic recording area, the total number of tracks is 27, and if 1fc is 1 bit, the magnetic recording medium is One side has a recording capacity of 560 kbytes.

After performing the above-mentioned recording on the magnetic card, the operation of putting in and out of the commercially available card case 50,000 times was performed.
Further, the reproduction signal was examined after standing at a temperature of 40 ° C. and a humidity of 90% for 1,000 hours.

[0031]

According to the present invention, a robust magnetic recording medium having a high recording density can be obtained, and it can be manufactured by a simple method.

Continuation of the front page (56) References JP-A-56-126903 (JP, A) JP-A-4-360016 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 1 / 14 G11B 5/62 G11B 5/74 G11B 5/84

Claims (2)

(57) [Claims] 1. Cobalt 5 to 25% by weight, chromium 15 to
35% by weight, the balance being iron as an essential component, and titanium,
One of vanadium, niobium, molybdenum, tungsten, tantalum, zirconium, silicon, and aluminum
A thin plate having a thickness of 0.5 to 3 mm, which is formed of an alloy containing 0.005 to 10% by weight of a seed or two or more elements, wherein the thin plate is magnetically anisotropic in a plate surface direction; In addition, the surface roughness of the flat portion serving as the magnetic recording surface of the thin plate is finished.
A recording wavelength of 1/10 or less of the recording wavelength. 2. 5 to 25% by weight of cobalt, 15 to 25% of chromium
35% by weight, the balance being iron as an essential component, and titanium,
One of vanadium, niobium, molybdenum, tungsten, tantalum, zirconium, silicon, and aluminum
After melting a mixture or alloy having a composition comprising 0.005 to 10% by weight of a seed or two or more elements, forging is performed by casting to form an ingot and subjecting the obtained ingot to a solution treatment. And then cold rolling and / or
Alternatively, after performing hot rolling to form a thin plate, the obtained thin plate is subjected to aging treatment while applying a magnetic field in a parallel direction, and then the surface roughness of a flat portion serving as a magnetic recording surface of the thin plate is set to a recording wavelength of 1 /
10. A method for manufacturing a magnetic recording medium, comprising finishing a thin plate to a thickness of 0.5 to 3 mm or less.