US3929978A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing ferromagnetic chromium dioxide
Assignee: Montedison SpA
•
Filing: 1972-03-01
•
Granted: 1975-12-30
•
Expires: 1992-03-01
Abstract
Abstract Ferromagnetic chromium dioxide is formed by heating a hydrated chromium (III) chromate of the formula Cr2(CrO4)3.nH2O wherein n varies between 1 to 8 at a temperature ranging from 250* to 500*C under an oxygen pressure of 30 to 1000 atmospheres. The resulting product is pure, without modifiers, and has magnetic characteristics which makes it very suitable for use in magnetic recording applications.
Inventors
- 👤 Domenico Morero
- 👤 Ugo Montiglio
- 👤 Pierfrancesco Aspes
- 👤 Giampiero Basile
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 00:14
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/0302; H01F1/0311; H01F1/0313; C; C01; C01G; C01G37/00; C01G37/02; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70636; C01P; C01P2002/00; C01P2002/70; C01P2002/72; C01P2002/74; C01P2002/80; C01P2002/82; C01P2004/00; C01P2004/10; C01P2004/54; C01P2004/60; C01P2004/62; C01P2006/00; C01P2006/42; C01P2006/80; C01P2006/82
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
20 words
A PROCESS FOR PREPARING HIGH QUALITY FERROMAGNETIC CHROMIUM DIOXIDE CONSISTING OF HEATING A CHROMIUM (III) CHROMATE SALT OF THE FORMULA
Claim 2
Dependent Claim
20 words
A PROCESS FOR PREPARING HIGH QUALITY FERROMAGNETIC CHROMIUM DIOXIDE CONSISTING OF HEATING A CHROMIUM (III) CHROMATE SALT OF THE FORMULA
Claim 3
Dependent Claim
15 words
The process according to claim 1, wherein the heating temperature is between 300* and 350*C.
Claim 4
Dependent Claim
16 words
The process according to claim 1, wherein the oxygen pressure is between 200 and 350 atm.
Claim 5
Dependent Claim
22 words
The process according to claim 1, wherein the hydrated chromium (III) chromate starting material contains from 1 to 4 moles of water.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |