US5122423A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium comprising a chromium underlayer deposited directly on an electrolytic abrasive polished high purity aluminum alloy substrate
Assignee: Kobe Steel Ltd
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Filing: 1989-03-21
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Granted: 1992-06-16
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Expires: 2009-03-21
Abstract
Abstract Magnetic recording media, wherein a substrate of Al-Mg alloy prepared from aluminum metal at a purity of higher than 99.99% is surface finished by electrolytic abrasive polishing and a thin film layer of ferromagnetic material is formed thereover as a recording layer. The Al-Mg alloy is preferably prepared by rapid-cooling solidification.
Inventors
- 👤 Takashi Hase
- 👤 Hiromi Matsumura
- 👤 Yoshihiko Onishi
- 👤 Hidetaka Hayashi
- 👤 Motoharu Sato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:42
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/658; G11B5/72; G11B5/727; G11B5/73; G11B5/7368; G11B5/7373; G11B5/739; G11B5/73911; G11B5/73917; G11B5/73919; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/12493; Y10T428/12535; Y10T428/12625; Y10T428/12736; Y10T428/12743
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
71 words
Magnetic recording media made by the steps comprising: forming a substrate of Al-Mg alloy from aluminum metal of purity higher than 99.99%, surface finishing said substrate by electrolytic abrasive polishing whereby the surface roughness is less than 0.01 μm, forming an underlayer of Cr directly on the substrate which improves the magnetic characteristics of a thin film of ferromagnetic material, then forming a thin film of ferromagnetic material over said underlayer.
Claim 2
Dependent Claim
71 words
Magnetic recording media made by the steps comprising: forming a substrate of Al-Mg alloy from aluminum metal of purity higher than 99.99%, surface finishing said substrate by electrolytic abrasive polishing whereby the surface roughness is less than 0.01 μm, forming an underlayer of Cr directly on the substrate which improves the magnetic characteristics of a thin film of ferromagnetic material, then forming a thin film of ferromagnetic material over said underlayer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-06-16 | 1995-12-16 | 1996-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-06-16 | 1999-12-16 | 2000-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-06-16 | 2003-12-16 | 2004-06-16 | $7700.00 | Window Closed / Lapsed |