JPH02192010A - Thin metallic film type magnetic recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a metal thin film magnetic recording medium with excellent noise characteristics.

[Conventional technology]

Recently, metal thin film magnetic recording media, in which the magnetic film on a nonmagnetic substrate is a ferromagnetic metal thin film, have been used as recording media for magnetic recording devices, and due to their high density recording properties, they have been replaced by conventional so-called coated magnetic recording media. It is being replaced. The composition of the ferromagnetic metal thin film formed on the non-magnetic substrate is determined by comprehensively evaluating magnetic properties, recording/reproducing characteristics, surface weatherability, etc. or CoNiC
R-based alloys are used.

[Problem to be solved by the invention]

The present invention aims to provide a magnetic recording medium with improved noise characteristics in order to further enable high-density recording of the metal thin film type magnetic recording medium.

[Means and effects for solving the problems] In the metal thin film magnetic recording medium of the present invention, the metal-based magnetic film satisfies the following formula (1
) or CoCrN having the component composition shown by [■]
It is characterized by being made of a b-based or CoCrNiNb-based alloy.

COI-X-ZCrxN bz ”' CI
:ICo+-x-y-zcrxNiyNbz -(
]I] In the formula, X, y, z represent the composition ratio, and X is 0.07
~0.15, y is 0.05~0.25, z is 0.01~
It is 0.10.

As mentioned above, the metal-based magnetic film of the magnetic recording medium of the present invention is based on CoCr-based or CoCrNi-based alloy,
It has a composition in which Nb is added to this. CoCr
CoCrNi-based and CoCrNi-based alloys are alloys with high coercive force (Hc) and high residual magnetic flux density (Br), and by adding an appropriate amount of Nb to them according to the present invention, the deterioration of their magnetic and electrical properties can be prevented. A remarkable improvement effect on recording/reproduction noise characteristics can be obtained without any interference. This is because the addition of an appropriate amount of Nb causes changes in the magnetocrystalline anisotropy of the magnetic film, refinement of crystal grains, concentration of Cr grain boundaries, etc. As a result, the magnetic domains become refined and isolated, leading to magnetization transitions. This is thought to be due to a decrease in width.

In the present invention, regarding the alloy component composition of the magnetic film, Cr1i
The reason why (x) is set to 0.07 to 0.15 is that if it is less than 0.07, the weather resistance of the magnetic film will be insufficient, while if it is more than 0.15, it will not be possible to ensure good magnetic and electrical properties. It is from. In addition, the lower limit of the amount of Ni (y) in the case of a magnetic film containing Ni is set to 0.05 in order to ensure that the effect of improving weather resistance by adding Ni is sufficient, and the upper limit is set to 0.25. This is because if it exceeds this value, the saturation magnetic flux density (Bs) decreases, making it impossible to obtain good magnetic and electrical properties.

Furthermore, regarding the amount of Nb (2), the lower limit was set to 0.01 in order to ensure the sufficient reduction effect of the magnetization transition width due to the addition of Nb, while the upper limit was set to 0.10. This is because, if it exceeds this value, not only the effect will be almost saturated, but also the magnetic and electrical properties will deteriorate. The noise characteristic improvement effect of this Nb addition is as follows:
COI or C that requires the coexistence of Cr and does not contain Cr
This cannot be obtained with oNi systems, etc. Therefore, in the present invention, CoC
The base alloys are r-based and CoCrNi-based.

The metal thin film magnetic recording medium of the present invention includes magnetic disks, magnetic drums, magnetic tapes, magnetic sheets, and the like. These can be manufactured according to known processes and conditions, except that the magnetic film is made of a CoCrNb-based or CoCrNiNb-based alloy having a composition represented by the formula [1] or [■]. For example, regarding a magnetic disk for in-plane recording, the base material is an aluminum alloy plate, and the surface thereof is coated with a hard N1-P plating film (thickness: e.g. 15 to 25 μm) by electroless plating.
After applying a texture treatment to the plated film surface, Cr is applied as an underlayer to give in-plane anisotropy to the magnetic film.
A film is formed to have an appropriate thickness (for example, 500 to 3000 people). A magnetic film (film thickness: 500 to 2000 layers, for example) having the above composition is formed on the Cr film surface. Next, as a protective film to prevent abrasion and damage to the magnetic film, a film with lubricity and wear resistance, such as a carbonaceous film (thickness: e.g. 150 to 600 layers), is formed to create a multilayered structure. A magnetic disk for longitudinal recording is obtained. The laminated structure is not limited to the above example. For example, before forming a carbonaceous film on a magnetic film, a Cr film (film thickness of about 100 to
By forming a carbonaceous film on the surface of the magnetic film, the weather resistance of the magnetic disk can be further improved by forming a lubricant (film thickness: e.g. 10 to 100) on the surface. It is also possible to provide a better protective lubrication function for the magnetic head. Note that each layer can be formed by a sputtering method, an ion blating method, a vacuum evaporation method, or the like.

[Example] W (Co Cr N b based magnetic film) (I) Production of test magnetic disk Aluminum alloy substrate (outer diameter 130 mm, inner diameter 40 mm)
A Ni-P electroless plating film (film thickness 20 μm) was formed on the surface of the film (film thickness 1.9 mm), and the surface was polished and textured, followed by magnetron sputtering (argon atmospheric pressure: 7 Xl0-2t
A test magnetic disk was prepared by laminating a Cr film as an underlayer, a CoCr-based or CoCrNb-based alloy film as a magnetic layer, and a carbonaceous film (thickness: 300 mm) as a lubricating film in this order using I got it.

In addition, in order to make a fair comparison of the recording and reproducing characteristics (noise characteristics) of each magnetic disk under test, the intrinsic coercive force (Hc), residual magnetic flux density (Br), and film thickness (δ ) The underlayer and the magnetic film were formed so that the product (Br·δ) was equal to each other.

Its Hc is 10500 e, and Br・δ is 450 G.
, μ.

(IT) Recording/reproduction characteristics test (noise characteristics test) Signal recording/reproduction was performed using a ferrite head on each sample magnetic disk at a recording linear density of 20 KPCI and 28 KPCI, and the reproduction signal output and media noise intensity were measured. The ratio (S/N, dB) and modulation noise (μVrms) were determined. The specifications of the head are: gap width: 18.6μ, gap length: 0.14μ, inductance = 8μH, flying hide: 0.22μ, loading force: 9.58f, and the number of coil turns is 24.

The test results for each sample magnetic disk are shown in Table 1 together with the alloy composition of the magnetic film. In the table, No. 11 to 14 are invention examples, No. 15 is a comparative example, column A shows the case where the recording linear density is 20 KPCI, and column B shows the case where the recording linear density is 28 KPCI.

Test magnetic disks were obtained using the same process and conditions as in Example 1, except that the magnetic film alloy was CoCrNi or CoCrNiNb. Same recording and playback characteristics (
Noise characteristics) tests were conducted. Table 2 shows the magnetic film alloy composition and test results of each test magnetic disk. In the table, No.
, 21 to 24 are invention examples, No. 25 is a comparative example, and A
Column and B column show cases where the recording linear density is 20 KPCI and 28 KFCI, respectively.

As is clear from the test results of each of the above examples, CoCr
The magnetic disk of the invention example having a magnetic film made of an Nb-based or CoCrNiNb-based alloy has improved noise characteristics compared to a conventional product having a magnetic film made of a CoCr-based or CoCrNi-based alloy that does not contain Nb. The effect becomes more pronounced as the recording linear density becomes higher.

〔Effect of the invention〕

The metal thin film magnetic recording medium of the present invention has excellent noise characteristics and low recording/reproduction noise, making it possible to perform higher density recording than conventional products, thereby making the magnetic recording medium more compact and capable of improving quality and performance. Effects such as this can be obtained.

Claims (1)

[Claims] 1. In a magnetic recording medium in which a metal-based magnetic film is formed on a non-magnetic substrate, the metal-based magnetic film is Co_1_-_x_
−_zCr_xNb_z [However, x is 0.07 to 0.1
5, z is 0.01 to 0.10] A metal thin film type magnetic recording medium having excellent noise characteristics. 2. In a magnetic recording medium in which a metal-based magnetic film is formed on a non-magnetic substrate, the metal-based magnetic film is Co_1_-_x_
-_y_-_zCr_xNi_yNb_z [However, x is 0.07 to 0.15, y is 0.05 to 0.25, z is 0
．． 01 to 0.10] A metal thin film magnetic recording medium having excellent noise characteristics.