US4540600A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing a magnetic recording medium
Assignee: TDK Corp
•
Filing: 1984-03-12
•
Granted: 1985-09-10
•
Expires: 2004-03-12
Abstract
Abstract A process for producing a magnetic recording medium which comprises forming on a non-magnetic substrate a magnetic thin layer composed of columnar crystal particles comprising Co, or Co and Ni and/or Cr by vapor/depositing the metal atoms at an angle of incidence of at least 20° relative to the normal line of the principal plane of the substrate, and then forcibly oxidizing the magnetic thin layer by electrochemical treatment to form an oxide layer on the surface of the columnar crystal particles of the magnetic thin layer, and thereby to form a magnetic layer.
Inventors
- 👤 Koji Kobayashi
- 👤 Kiyoshi Noguchi
- 👤 Suguru Takayama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:41
CPC Classifications
C; C23; C23C; C23C14/00; C23C14/22; C23C14/225; C23C14/226; G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/658; G11B5/84; G11B5/85; H; H01; H01F; H01F41/00; H01F41/14; H01F41/16; Y; Y10; Y10S; Y10S205/00; Y10S205/922
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
107 words
A process for producing a magnetic recording medium which comprises forming on a non-magnetic substrate a magnetic thin layer composed of columnar crystal particles comprising Co, or Co and Ni and/or Cr by vapor-depositing the metal atoms at an angle of incidence of at least 20° C. relative to the normal line of the principal plane of the substrate, and then oxidizing the magnetic thin layer by anodic oxidation to form an oxide layer on the surface of the columnar crystal particles of the magnetic thin layer wherein the atomic ratio of O/(Co or Co+Ni) is from 0.1 to 0.5, and thereby to form a magnetic layer.
Claim 2
Dependent Claim
107 words
A process for producing a magnetic recording medium which comprises forming on a non-magnetic substrate a magnetic thin layer composed of columnar crystal particles comprising Co, or Co and Ni and/or Cr by vapor-depositing the metal atoms at an angle of incidence of at least 20° C. relative to the normal line of the principal plane of the substrate, and then oxidizing the magnetic thin layer by anodic oxidation to form an oxide layer on the surface of the columnar crystal particles of the magnetic thin layer wherein the atomic ratio of O/(Co or Co+Ni) is from 0.1 to 0.5, and thereby to form a magnetic layer.
Claim 3
Dependent Claim
22 words
The process according to claim 1, wherein the magnetic layer contains Ni, and the weight ratio of Co/Ni is at least 1.5.
Claim 4
Dependent Claim
25 words
The process according to claim 1, wherein the magnetic layer contains Cr, and the weight ratio of Cr/(Co or Co+Ni) is from 0.001 to 0.1.
Claim 5
Dependent Claim
19 words
The process according to claim 1, wherein the magnetic layer has a thickness of from 0.05 to 0.5 μm.
References Cited (Backward Citations)
US4239835A
Cited
US4350574A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-09-09 | 1989-03-11 | 1989-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-09 | 1993-03-11 | 1993-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-09 | 1997-03-11 | 1997-09-10 | $7700.00 | Window Closed / Lapsed |