US4639815A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium with chromiumiron protective layer
Assignee: Fujifilm Holdings Corp
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Filing: 1984-04-27
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Granted: 1987-01-27
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Expires: 2004-04-27
Abstract
Abstract A magnetic recording medium comprising a non-magnetic support, a thin magnetic metal film on the support, and a protective layer on the thin magnetic film, the protective layer containing chromium and iron, the chromium being present in an amount of 6 to 40 wt % and the iron being the remainder. The protective layer may optionally contain up to 20% by weight nickel.
Inventors
- 👤 Yoshihiro Arai
- 👤 Akira Nahara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:37
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; G11B5/726; G11B5/7262; G11B5/722; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12771; Y10T428/12861; Y10T428/12951
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
86 words
A magnetic recording medium comprising a non-magnetic support, a thin magnetic metal film on the support, and a protective layer on the thin magnetic film, to improve corrosion and scraping resistance, said protective layer containing chromium and iron and nickel, the chromium being present in an amount of 6 to 40 wt % nickel in an amount of not more than 20 wt % and iron, being the remainder, wherein the protective layer has a thickness in a range of from 10 Å to 200 Å.
Claim 2
Dependent Claim
86 words
A magnetic recording medium comprising a non-magnetic support, a thin magnetic metal film on the support, and a protective layer on the thin magnetic film, to improve corrosion and scraping resistance, said protective layer containing chromium and iron and nickel, the chromium being present in an amount of 6 to 40 wt % nickel in an amount of not more than 20 wt % and iron, being the remainder, wherein the protective layer has a thickness in a range of from 10 Å to 200 Å.
Claim 3
Dependent Claim
18 words
A magnetic recording medium as claimed in claim 1 additionally comprising a lubricating layer on the protective layer.
Claim 4
Dependent Claim
45 words
A magnetic recording medium as claimed in claim 1, wherein the protective layer the chromium is present in an amount of 10 to 40 wt % chromium, and nickel is present in an amount of 0 to 10 wt %, with iron being the remainder.
Claim 5
Dependent Claim
22 words
A magnetic recording medium as claimed in claim 1, wherein the protective layer has a thickness of 30 Å to 150 Å.
Claim 6
Dependent Claim
22 words
A magnetic recording medium as claimed in claim 1, wherein the protective layer has a thickness of 100 Å to 150 Å.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-01-26 | 1990-07-28 | 1991-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-26 | 1994-07-28 | 1995-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-26 | 1998-07-28 | 1999-01-27 | $7700.00 | Window Closed / Lapsed |