JPS61199230A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the crystal orientation and magnetic characteristic of a magnetic layer and to increase the number of times of CSS by providing a nonmagnetic underlying layer consisting of one kind among WO3, WC2, WC, WN2 and W2N between a nonmagnetic hardened layer and magnetic medium layer. CONSTITUTION:An alumite film is coated as the nonmagnetic hardened layer 2 to about 4mum on a disk-shaped aluminum alloy substrate 1. After the film is finished to a specular surface, the film consisting of one kind among WO3, WC2, WC, WN2 and W2N is formed as the nonmagnetic underlying layer 3 thereon to the thickness ranging 50-2,400Angstrom and a thin gamma-Fe2O3 film is formed as the magnetic medium layer 4 thereon. The adverse effect of the nonmagnetic hardened layer 2 is prevented and the crystal orientation and magnetic characteristic of the magnetic layer are improved by providing the nonmagnetic underlying layer 3 consisting of, for example, the WO3 in the above-mentioned manner. The increase in the number of times of CSS is thus made possible.

Description

[Detailed description of the invention] [Industrial application field] This invention applies, for example, to cobalt and cobalt alloys.

The present invention relates to a magnetic recording medium having a magnetic layer made of a metal ferromagnetic material such as iron, iron alloy, nickel, or nickel alloy, or a magnetic layer made of a metal oxide ferromagnetic material such as iron oxide or chromium oxide.

[Conventional technology]

In recent years, the importance of external storage devices such as magnetic disks in computer systems has increased, and the demand for higher recording densities is increasing.

A magnetic recording device is composed of the main components of a recording/reproducing head and a magnetic disk. The magnetic disk rotates at high speed, and the recording/reproducing head floats a minute distance above the magnetic disk.

As the performance of magnetic recording devices improves, the load on the recording/reproducing head is reduced in order to reduce the flying distance, and contact start/stop (contact start/stop: c
ss) W head flotation system is adopted. In order to increase the recording density and performance of magnetic disks, that is, magnetic recording media, K is to make the recording media thinner, more uniform, and improve magnetic properties (improvement of coercive force and squareness ratio).

In addition, it is necessary to improve the precision of the disk surface and the head crash resistance in order to ensure a stable head flying state in low-flying measures and prevent collisions between the head and the disk (head crash).

Accordingly, it has become important to improve the quality of the substrate that supports the magnetic medium layer.

Conditions for a substrate suitable for high-density recording include good mechanical flatness and surface roughness, and a small number of defects. Furthermore, as the recording medium becomes thinner, the substrate needs to have sufficient hardness. In other words, if the substrate is soft, it will cause deformation such as depression when the magnetic head is connected to the magnetic disk, and not only will it be impossible to obtain a stable floating state of the V&K head, but also the contact start stop, which indicates the reliability of the magnetic recording device, will occur. (aSS) There is a problem that the number of times becomes small.

Traditionally, aluminum alloys have been used for the substrates of magnetic disks because of their surface hardening and surface precision.

A hardened layer is coated thereon. For this hardened layer, N1-P plated film or alumite film with good polishability has been used (for example, Electric Corporation Research and Practical Application Report Vol. 31, No. 9, pp. 1731-IT 44, Prior Art Patent Application No. 1983- 8863
No. 3, Japanese Patent Application No. 59-111488).

After forming this film, 2 machining processes are performed to improve the surface precision.
forming a magnetic medium layer; There is a close relationship between the magnetic properties and crystal orientation of this magnetic medium layer, and it is known that the crystal orientation is influenced by the type of underlying film of the magnetic medium layer (for example, Ota et al. Abstracts of Academic Lectures of the Japan Society of Applied Magnetics, 15PB-8 (1984)). For example, γ−
For Fe203 thin film, (111) orientation, C and C8
In the case of an alloy thin film, it is known that the magnetic properties are good when the film is 0-axis oriented.

[Problem that the invention seeks to solve]

However, when forming a magnetic medium layer by forming various hardened layers, in most cases the desired crystal orientation is not obtained. There was a problem that it was not possible.

This invention was made to solve the above-mentioned problems, and has good crystal orientation, that is, magnetic properties, and
The purpose is to obtain a highly reliable magnetic recording medium that can be used repeatedly.

[Means for solving problems]

The magnetic recording medium of the present invention has WO, WO2, WO, WN2. A nonmagnetic underlayer made of one of the following is formed.

[Effect]

wC3, we2. according to this invention. we, WN2.
By forming a non-magnetic underlayer made of any one of the following: and W2N, the adverse effects of the non-magnetic hardened layer can be prevented.

The crystal orientation of the magnetic medium layer can be improved.

The hardness and good surface precision characteristics of the non-magnetic hardened layer are not diminished.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 91
In the figure, 1) is an aluminum alloy substrate which is a non-magnetic substrate, (2) is a non-magnetic hardened layer, and (3) is a WO.

The non-magnetic underlayer (4) is a magnetic medium layer.

EXAMPLES Hereinafter, the present invention will be specifically explained in more detail with reference to Examples, but the present invention is not limited thereto.

EXAMPLE A 4 μm thick alumite film was coated as a nonmagnetic hardened layer (2) on a disk-shaped aluminum alloy substrate. After mirror-finishing the alumite film, a WO3 film was formed as a nonmagnetic underlayer (3) by reactive sputtering.

Furthermore, a γ-Fe203 thin film was formed as a magnetic medium layer (4).

Samples with different film thicknesses of WO3 were prepared and nine different measurements were performed, and the results are summarized in a table. The crystal orientation was measured by X-ray diffraction and expressed by the ratio of γ-re2o (spinel type) between the peak r (222) in the 222 direction and the peak I (311) in the 311 direction. The squareness ratio S* was determined from the magnetization curve.

Furthermore, FIG. 2 shows an example of the thickness of the non-magnetic underlayer and changes in each characteristic value when the non-magnetic underlayer is N03.

An example in which the nonmagnetic underlayer is wC is shown in FIG. In the figure, 9 curves 11 represent changes in I (222)/I (311), 9 curves 12 represent changes in S*, and 9 curves 13 represent changes in the ratio of aSS times.

Note) The number of aSS when the WO3 film thickness is oX (not formed) is taken as 1 and expressed as a ratio.

As is clear from the table and Figure 2, the film thickness of WO3 is s
When oX is exceeded, the crystal orientation and the S value improve. On the other hand, the film thickness of WO3 exceeds 2400X and is 3000X.
When the number of aSSs exceeded X, the number of aSSs worsened. W
It is thought that if the film thickness of O. Moreover, if it is more than 3000X, cracks will often occur due to the difference in the coefficient of thermal expansion, so it is not desirable to have more than 3000X.

In the above embodiment, the case of WO3 film was explained, but
WC2, WC2WN2. Even in the case of W2N, similar effects can be obtained, and the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a nonmagnetic substrate and a nonmagnetic hardened layer stored on the nonmagnetic substrate.

wC3, wC2, wC coated with this non-magnetic hardened layer.

Since it includes a non-magnetic underlayer made of one of WN and W2N and a magnetic medium layer coated on this non-magnetic underlayer, crystal orientation and magnetic properties are improved,
This has the effect of increasing the number of O88 cycles and providing a highly reliable magnetic recording medium.

Also, WOS, WO2, WC, WN2. and W2N
The thickness of the non-magnetic underlayer made of any one of the following:
When the range is 0 to 2400X, the above-mentioned effects are further enhanced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a magnetic recording medium obtained by an embodiment of the present invention, and FIGS. 2 and 3 are characteristic diagrams showing changes in the film thickness of the nonmagnetic underlayer and each characteristic value. be. +11...Nonmagnetic substrate, (2)...Nonmagnetic hardened layer,
(3)...WO3 nonmagnetic underlayer, (4)...magnetic medium layer.

Claims (2)

[Claims] (1) A non-magnetic substrate, a non-magnetic hardened layer coated on this non-magnetic substrate, and WO_3 coated on this non-magnetic hardened layer,
A magnetic recording medium comprising a nonmagnetic underlayer made of any one of WC_2, WC, WN_2, and W_2N, and a magnetic medium layer covered with the nonmagnetic underlayer. (2) WO_3, WC_2, WC, WN_2, and W
2. The magnetic recording medium according to claim 1, wherein the nonmagnetic underlayer made of any one of _2N has a thickness in the range of 50 to 2400 Å.