US3684590A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for maintaining nitriding atmosphere
Assignee: United States Steel Corp
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Filing: 1971-02-08
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Granted: 1972-08-15
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Expires: 1991-02-08
Abstract
Abstract A METHOD AND APPARATUS FOR NITRIDING A STEEL SURFACE WITH A BINARY MIXTURE OF AMMONIA AND HYDROGEN AT ELEVATED TEMPERATURES AND ATMOSPHERIC PRESSURE WHEREIN THE GAS MIXTURE IS RECIRCULATED AND SCRUBED TO REMOVE HARMFUL IMPURITY GASES WHICH RETARD NITRIDING, AND WHEREIN A MEASURABLE PARTIAL PRESSURE OF WATER IN SAID GAS MIXTURE IS MAINTAINED TO SUPRESS THE FORMATION OF SAID HARMFUL IMPURITIES AND TO ADJUST THE WATER PARTIAL PRESSURE OF SAID GAS TO VALUE WITHIN THE RANGE 1 TO 25 TORR.
Inventors
- 👤 Harry H Podgurski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 05:24
CPC Classifications
C; C23; C23C; C23C8/00; C23C8/06; C23C8/08; C23C8/24; C23C8/26
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-15 | 1976-02-14 | 1976-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-15 | 1980-02-14 | 1980-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-15 | 1984-02-14 | 1984-08-15 | $7700.00 | Window Closed / Lapsed |