Patent US3886025A successfully refreshed from Google Patents.
US3886025A
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US
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Ferrite head
Assignee: International Business Machines Corp
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Filing: 1972-08-24
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Granted: 1975-05-27
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Expires: 1992-08-24
Abstract
Abstract Ferrite recording head members are coated with a layer of silicon nitride prior to filling the gap between the members with nonmagnetic material. The silicon nitride coating protects the ferrite member from attack by the nonmagnetic material.
Inventors
- 👤 Jacob Riseman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:53
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/133; G11B5/187; G11B5/23; G11B5/232; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/4902; Y10T29/49021; Y10T29/49032; Y10T29/49036; Y10T29/49039; Y10T29/49055; Y10T29/49057
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
74 words
IN A PROCESS FOR FORMING A FERRITE HEAD HAVING A PAIR OF FERRITE MEMBERS AND A GLASS FILLED GAP THEREBETWEEN IN WHICH SAID GLASS FILLED IS FORMED BY POSITIONING SAID FERRITE MEMBERS SO THAT THE GAP FORMING SURFACES ARE OPPOSED TO EACH OTHER AND FLOWING MOLTEN GLASS GAPPING MATERIAL INTO SAID GAP, THE IMPROVEMENT WHICH COMPRISES FORMING A LAYER OF SILICON NITRIDE ON SAID MEMBERS WHICH LAYER IS AT LEAST CO-EXTENSIVE WITH SAID GLASS.
Claim 2
Dependent Claim
74 words
IN A PROCESS FOR FORMING A FERRITE HEAD HAVING A PAIR OF FERRITE MEMBERS AND A GLASS FILLED GAP THEREBETWEEN IN WHICH SAID GLASS FILLED IS FORMED BY POSITIONING SAID FERRITE MEMBERS SO THAT THE GAP FORMING SURFACES ARE OPPOSED TO EACH OTHER AND FLOWING MOLTEN GLASS GAPPING MATERIAL INTO SAID GAP, THE IMPROVEMENT WHICH COMPRISES FORMING A LAYER OF SILICON NITRIDE ON SAID MEMBERS WHICH LAYER IS AT LEAST CO-EXTENSIVE WITH SAID GLASS.
Claim 3
Dependent Claim
18 words
The process of claim 1 wherein the entire surfaces of the ferrite members are coated with silicon nitride.
Claim 4
Dependent Claim
20 words
The process of claim 1 wherein said silicon nitride layer has a thickness of from about 200 to 1,000 angstroms.
Claim 5
Dependent Claim
30 words
The process of claim 1 wherein said silicon nitride coating is applied by heating the ferrite members in the presence of a gaseous mixture of a silicon compound and ammonia.
References Cited (Backward Citations)
US448915A
Cited
US2820720A
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US3494026A
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US3479738A
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US3562444A
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US3578920A
Cited
US3650737A
Cited
US3544982A
Cited
US3663767A
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US3551202A
Cited
US3672045A
Cited
US3737583A
Cited
US3778896A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |