Patent US2705701A successfully refreshed from Google Patents.
US2705701A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for preparing magnetic compositions
Assignee: Henry L Crowley & Co Inc
•
Filing: 1952-11-28
•
Granted: 1955-04-05
•
Expires: 1972-11-28
Abstract
No abstract record available.
Inventors
- 👤 Henry L Crowley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:03
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/26
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
149 words
IN A METHOD OF PREPARING A MAGNETIC COMPOSITION IN WHICH AN INITIAL OXIDE MIXTURE CONTAINING AT LEAST 50% BY WEIGHT OF FERRIC OXIDE AND AT LEAST ONE OTHER METAL OXIDE IS SUBJECTED TO HEAT-TREATMENT IN MULTI-STAGES INCLUDING PRE-FIRING AND FINAL-FIRING AT TEMPERATURES WITHIN THE RANGE OF 800 TO 1500* C., THE IMPROVEMENT WHICH COMPRISES GRINDING THE PRE-FIRED PRODUCT TO A RELATIVELY FINE POWDER, PREPARING FROM THE FINELY-GROUND PRE-FIRED PRODUCT A SELECTIVELY-SIZED POWDER OF WHICH FROM ABOUT 40% TO ABOUT 50% BY WEIGHT IS OF A PARTICLE SIZE BETWEEN 5 AND 10 MICRONS, FROM ABOUT 35% TO ABOUT 20% BY WEIGHT IS OF A PARTICLE SIZE UP TO 5 MICRONS, AND FROM ABOUT 40% TO ABOUT 25% BY WEIGHT IS OF A PARTICLE SIZE BETWEEN 10 AND 40 MICRONS, FORMING SAID SELECTIVELY-SIZED POWDER INTO DENSELY-PACKED SHAPED ARTICLES, AND SUBJECTING SAID ARTICLES TO FINAL-FIRING AT A TEMPERATURE WITHIN THE AFOREMENTIONED RANGE.
Claim 2
Dependent Claim
149 words
IN A METHOD OF PREPARING A MAGNETIC COMPOSITION IN WHICH AN INITIAL OXIDE MIXTURE CONTAINING AT LEAST 50% BY WEIGHT OF FERRIC OXIDE AND AT LEAST ONE OTHER METAL OXIDE IS SUBJECTED TO HEAT-TREATMENT IN MULTI-STAGES INCLUDING PRE-FIRING AND FINAL-FIRING AT TEMPERATURES WITHIN THE RANGE OF 800 TO 1500* C., THE IMPROVEMENT WHICH COMPRISES GRINDING THE PRE-FIRED PRODUCT TO A RELATIVELY FINE POWDER, PREPARING FROM THE FINELY-GROUND PRE-FIRED PRODUCT A SELECTIVELY-SIZED POWDER OF WHICH FROM ABOUT 40% TO ABOUT 50% BY WEIGHT IS OF A PARTICLE SIZE BETWEEN 5 AND 10 MICRONS, FROM ABOUT 35% TO ABOUT 20% BY WEIGHT IS OF A PARTICLE SIZE UP TO 5 MICRONS, AND FROM ABOUT 40% TO ABOUT 25% BY WEIGHT IS OF A PARTICLE SIZE BETWEEN 10 AND 40 MICRONS, FORMING SAID SELECTIVELY-SIZED POWDER INTO DENSELY-PACKED SHAPED ARTICLES, AND SUBJECTING SAID ARTICLES TO FINAL-FIRING AT A TEMPERATURE WITHIN THE AFOREMENTIONED RANGE.
References Cited (Backward Citations)
US2283925A
Cited
US2575099A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1958-04-04 | 1958-10-04 | 1959-04-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1962-04-04 | 1962-10-04 | 1963-04-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1966-04-04 | 1966-10-04 | 1967-04-05 | $7700.00 | Window Closed / Lapsed |