JP2626737B2 - Solid lubrication film structure of magnetic recording media - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a film structure of a solid lubricating film for covering and protecting a magnetic film surface of a metal thin-film magnetic recording medium.

[Conventional technology]

In a metal thin film type magnetic recording medium in which a metal thin film is formed as a magnetic film on a non-magnetic substrate, in order to stabilize the function as the recording medium and the service life, it is necessary to use the recording / reproducing Needless to say, it is necessary to smooth the contact with the porcelain head and to prevent wear and damage of the magnetic head and the magnetic film. Conventionally, a liquid lubricant has been applied to the surface of the magnetic film or a solid lubricant has been kneaded into the magnetic film in order to protect the film surface and improve the lubricity between the contact surfaces. However, the former has a drawback that the magnetic head is attracted by the surface tension of the liquid lubricant and the liquid lubricant is easily scattered and disappears, resulting in poor durability. (Limit of recording density). In recent years, as an alternative to this, formation of a diamond-like or graphite-like solid carbonaceous film on a magnetic film surface by a vacuum deposition method, a sputtering method, or the like has been proposed and is being put to practical use.

[Problems to be Solved by the Invention] The solid carbonaceous film has no defects in a lubrication system such as application of a liquid lubricant or kneading of a solid lubricant, and has lubricity and wear resistance superior to those systems. I have,
Its lubricating function and durability are not always satisfactory.

In view of this point, the present invention has been made with the object of further improving the lubricating properties and durability of a carbonaceous film of a magnetic recording medium using a solid carbonaceous film as a lubricating film.

[Means and actions for solving the problems]

The lubricating film structure of the present invention has a two-layer structure in which a solid carbonaceous film covering the surface of a metal-based magnetic film on a nonmagnetic substrate is composed of a hard carbonaceous film and a soft carbonaceous film laminated thereon. And the thickness of the hard carbonaceous film is 150 to 400 °, and the thickness of the soft carbon film is 20 to 100 °.

The solid lubricating film covering the magnetic film surface has a fine uneven surface. Factors of abrasion of the film surface caused by sliding of the magnetic head on the film surface include adhesion of the true contact area of the friction surface protrusion, and shearing and digging. Assuming that the real contact area between the lubricating film surface and the sliding surface of the magnetic disk is A and the shear strength of the film material at the contact interface is S, the friction coefficient μ based on the adhesion model is μ = F / W = A · S / W = S / P _S (where P _S = W / A is approximately equal to the hardness of the film material). In this regard, carbonaceous film is a solid lubricating film in the present invention has a two-layer structure comprising a lower layer of the hard carbon film and an upper soft carbonaceous film, high P _S by lower hard film Value and low S value due to the upper soft film, and therefore its coefficient of friction (μ) is low and has an excellent lubricating function.

In the present invention, the lower hard film of the solid carbonaceous film can be formed by an ion plating method, and the upper soft film can be formed by a sputtering method. According to the ion plating method, the carbon particles evaporated and ionized from the carbon source are accelerated by the electric field and adhere to the magnetic film surface, and the kinetic energy increased by the acceleration becomes binding energy on the magnetic film surface. As a result, the bonding between the carbon particles and the magnetic film surface is strengthened, and as a result, a dense and hard carbonaceous film is formed. On the other hand, the carbon source (target) is irradiated with ions by sputtering,
When a carbonaceous film is formed by attaching neutral particles of evaporating carbon to the surface of the magnetic film, the bonding between the carbon particles on the surface of the magnetic film is more gradual than that in the above-described ion plating method, and thus the carbon particles are formed. The carbonaceous film is relatively soft.

The lower hard film is formed by the above-described ion plating method under an Ar atmosphere at a degree of vacuum of 10 ⁻¹ to 10 ⁻² Torr,
It can be performed under the condition of 0.5 to 2.0 A, and the sputtering for forming the upper soft carbon film is performed at a vacuum degree of 0.
It can be performed in an Ar atmosphere of 3 to 7.0 × 10 ⁻² Torr.

The thickness of the lower hard film of the carbonaceous film having the two-layer structure is preferably 150 to 400 °. If the film thickness is less than 150 mm, the film strength is low, and the durability as a lubricating film is insufficient.On the other hand, if the film thickness exceeds 400 mm, the unevenness of the film surface becomes remarkable, This is because the coefficient of friction with the magnetic head increases. The thickness of the upper soft carbon film is suitably 20 to 100 °. If the film thickness is less than 20 mm,
When the film surface is easily scratched, it is difficult to stabilize the coefficient of friction at a low level. On the other hand, when the thickness is more than 100 mm, carbon abrasion powder tends to be generated on the contact surface with the magnetic head, which in turn promotes damage to the film surface. Because it will be.

The metal thin film type magnetic recording medium to which the present invention is applied includes a magnetic disk, various magnetic drums, magnetic tapes, magnetic sheets, and the like. All of them follow known general steps and conditions except that the carbonaceous film covering the surface of the magnetic film is formed as a two-layer structure film of a lower hard film and an upper soft film. Can be manufactured. For example, as for the in-plane recording porcelain disk, an aluminum alloy plate or the like is used as a base, and a hard Ni-P plating film (film thickness: for example, 15 to 25 μm) is provided on the surface thereof.
After applying a texturing treatment to the plating film surface, a Cr film (thickness: for example, 1300 to 5000 mm) is formed as an underlayer for imparting in-plane anisotropy to the magnetic film, and the magnetic film is formed on the Cr film surface. (Co, C
oNi, CoCr, CoNiCr, etc.) to a predetermined thickness (for example, 500 to
2000Å). The Cr film and the magnetic film are formed by various film forming methods such as sputtering, ion plating, and vacuum deposition. Next, a hard carbonaceous film is formed on the surface of the magnetic film by an ion plating method, and a soft oxygenaceous film is formed thereon by a sputtering method at a predetermined film pressure. Get.

〔Example〕

[I] Manufacture of test magnetic disk: Ni-P plating film, Cr film (film thickness) on aluminum alloy substrate
Hard carbon film formed by ion plating and soft carbonaceous film formed by sputtering on the magnetic film surface of a magnetic disk (51/2 "type) on which a 2500Å) and CoNiCr alloy magnetic film (thickness: 800Å) are formed. The ion plating was performed at a vacuum degree of 5 × 10 ^-2 To
rrAr, ionization current: 1 A, sputtering degree 2 × 1
0 ^-2 TorrAr.

[II] Friction test Rotational speed by bringing the magnetic head into contact with the test magnetic disk
After sliding at 100 rpm for 24 hours, coefficient of static friction (μs)
Was measured.

Table 1 shows the film configuration of the carbonaceous film of the accompanying test magnetic disk and the results of friction results. (Test No. No.) 1-4 are invention examples, No.
11 to 16 are comparative examples. No. 11 of Comparative Examples No. 11 to 16
Is a hard film only, No. 12 is an example of only a soft film, No. 13 to 16 are
It has a two-layer structure of a lower hard carbonaceous film and an upper soft carbonaceous film in the same manner as the invention example, but in the example where the film thickness of any two layers deviates from the definition of the present invention. is there.

As shown in Table 1, No. 1 lacks a hard carbonaceous film
No. 1 has a flaw on the film surface due to insufficient film strength, and No. 12 lacking a soft carbonaceous film has a large friction coefficient (μs) of 2.0 and poor lubricity. In addition, No. 13 to 16 in which one of the film thicknesses is excessive or insufficient even though it has a two-layer structure, have scratches due to insufficient wear resistance or film strength, or have poor lubricity. On the other hand, Nos. 1 to 4 of the invention examples have a friction coefficient (μs) of 1.0 or less and excellent stable lubricity,
Further, it is understood that the film strength and abrasion resistance are good and no flaw is generated.

[Effect of the Invention] The solid lubricating film structure of the magnetic recording medium of the present invention has an excellent lubricating function based on a laminating effect of a hard carbon film and a soft carbonaceous film and has good film strength and wear resistance. Therefore, a great effect can be obtained in improving and stabilizing the function of the magnetic recording medium as a recording medium and in improving its useful life.

Claims (1)

(57) [Claims] A solid carbonaceous film for covering a magnetic film surface of a magnetic recording medium having a metal-based magnetic film formed on a non-magnetic substrate,
It has a two-layer laminated structure composed of a hard carbonaceous film and a soft carbonaceous film formed thereon, and the thickness of the hard carbonaceous film is
A surface lubricating film structure for a magnetic recording medium, characterized in that the soft carbonaceous film has a thickness of 20 to 100 mm.