US4029541A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording disc of improved durability having tin-nickel undercoating
Assignee: Ampex Media Corp
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Filing: 1976-02-19
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Granted: 1977-06-14
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Expires: 1996-02-19
Abstract
Abstract A magnetic disc of improved durability is provided which has an undercoating of a relatively thick tin-nickel layer with a cobalt-containing magnetic layer over said tin-nickel layer and having an oxidized surface.
Inventors
- 👤 Malcolm Barlow
- 👤 Jerry R. Lundquist
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:53
CPC Classifications
H; H01; H01F; H01F10/00; H01F10/06; G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/7368; G11B5/7369; G11B5/739; G11B5/73911; G11B5/73917; Y; Y10; Y10S; Y10S205/00; Y10S205/917; Y10S205/922; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12708; Y10T428/12722
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
148 words
The process of making a magnetic recording medium comprising the following steps: a. providing a metallic, non-magnetic substrate, b. forming an electroless-nickel coating on said substrate, c. polishing said electroless-nickel coating, d. forming a tin-nickel layer over said electroless-nickel having a thickness of from 150 microinches to 1 mil. e. forming a magnetic film selected from cobalt-nickel-phosphorus and cobalt-phosphorus over said tin-nickel film, f. etching the surface of said film to produce a color change on said surface with an aqueous solution of a mild oxidizing agent selected from an aqueous nitric acid solution having a strength of 0.1 to 0.01 percent and an aqueous solution of ammonium persulfate having a strength of 0.01 to 1 percent, in the absence of a chelating agent, and g. baking the composite structure at a temperature of from 225° to 325° C. for a time of from 1/2 to 6 hours.
Claim 2
Dependent Claim
148 words
The process of making a magnetic recording medium comprising the following steps: a. providing a metallic, non-magnetic substrate, b. forming an electroless-nickel coating on said substrate, c. polishing said electroless-nickel coating, d. forming a tin-nickel layer over said electroless-nickel having a thickness of from 150 microinches to 1 mil. e. forming a magnetic film selected from cobalt-nickel-phosphorus and cobalt-phosphorus over said tin-nickel film, f. etching the surface of said film to produce a color change on said surface with an aqueous solution of a mild oxidizing agent selected from an aqueous nitric acid solution having a strength of 0.1 to 0.01 percent and an aqueous solution of ammonium persulfate having a strength of 0.01 to 1 percent, in the absence of a chelating agent, and g. baking the composite structure at a temperature of from 225° to 325° C. for a time of from 1/2 to 6 hours.
Claim 3
Dependent Claim
20 words
The process of claim 1, wherein the tin-nickel layer is not polished prior to the formation of the magnetic film.
Claim 4
Dependent Claim
16 words
The process of claim 1 wherein the composite structure is polished with diamond dust or alumina.
References Cited (Backward Citations)
US3321328A
Cited
US3460968A
Cited
US3471272A
Cited
US3719525A
Cited
US3681225A
Cited
US3886052A
Cited
US3674554A
Cited
US3767369A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-06-13 | 1980-12-13 | 1981-06-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-13 | 1984-12-13 | 1985-06-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-13 | 1988-12-13 | 1989-06-14 | $7700.00 | Window Closed / Lapsed |