Magnetic recording media

• US 4,717,622 A
• Filed: 03/11/1986
• Issued: 01/05/1988
• Est. Priority Date: 03/13/1985
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Mitani, Tsutomu, Kurokawa, Hideo, Yonezawa, Taketoshi
• Primary Examiner(s): Thibodeau, Paul J.
• Application Number:
  US06/838,814
• Time in Patent Office: 665 Days
• Field of Search: 428/694, 428/900, 428/408, 427/131, 427/402, 427/407.1, 427/34, 427/250, 204/192.11, 204/192.1
• US Class Current: 428/408
• CPC Class Codes: G11B 5/727 Inorganic carbon protective coating, e.g. graphite, diamond like carbon or doped carbon
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/30 Self-sustaining carbon mass or layer with impregnant or other layer
• CPC Class Codes: Y10T 428/31536 Including interfacial reaction product of adjacent layers

Abstract

A magnetic recording medium has a protective layer made of high hardness carbon synthesized under a low-temperature and a low-pressure by blowing hydrocarbon gas plasma onto a magnetic recording layer. The resistance thereof is large, and therefore, high density magnetic recording can be realized in a magnetic recording system wherein the magnetic head contacts the magnetic recording medium. Durability of the magnetic recording medium is substantially improved.

Claims

1. A magnetic recording medium, comprising:

a base material made of non-magnetic material;

a recording layer disposed on said base material, said recording layer being made of a ferromagnetic material; and

a protective layer disposed on said recording layer;

said protective layer being constituted by a diamond-like film of carbon having a Vicker'"'"'s hardness of more than 2000 kg/mm² and a specific resistance of 10⁷ Ω

·

cm to 10¹³ Ω

·

cm; and

said ferromagnetic material comprising an element which forms a carbide with carbon of said protective layer, in which said element is bonded to said carbon by covalent bonding or forms an intermetallic compound therewith.

2. The magnetic recording medium of claim 1, wherein:

said protective layer is an amorphous carbon layer consisting mainly of diamond-structure carbon.

3. The magnetic recording medium of claim 2, wherein:

said protective layer also includes graphitic carbon.

4. A method for making a magnetic recording medium, comprising:

(a) providing a base material made of non-magnetic material;

(b) successively, and in the same chamber,

(i) forming on said base material a recording layer made of ferromagnetic material by one of sputtering and vapor deposition, and

(ii) forming on said recording layer a protective layer of amorphous diamond by blowing a hydrocarbon gas plasma onto said recording layer while accelerating towards said recording layer ions of at least one chemical and electronic constituency in said plasma.

5. The method of claim 4, wherein:

said protective layer is constituted by a diamond-like film of carbon having a Vicker'"'"'s hardness of more than 2000 kg/mm² and a specific resistance of 10⁷ Ω

·

cm to 10¹³ Ω

·

cm.

6. The method of claim 5, wherein:

said ferromagnetic material comprises an element which forms a carbide with carbon of said protective layer, in which said element is bonded to said carbon by covalent bonding or forms an intermetallic compound therewith.

7. The method of claim 6, wherein:

said protective layer is an amorphous carbon layer consisting mainly of diamond-structure carbon.

8. The method of claim 7, wherein:

said protective layer also includes graphitic carbon.