Hard magnetic ferrites
Abstract
Abstract HARD MAGNETIC FERRITES OF THE FORMULA MO.6FE2O3 WHERE M IS BARIUM, STRONTIUM OR LEAD, ARE MADE BY PROVIDING A MOTLEN BORATE COMPOSITION CONTAINING THE METAL OXIDE AND FERRIC OXIDE IN AMOUNTS CORRESPONDING TO THE DESIRED FERRITE, COOLING THE MELT BELOW THE LIQUIDUS EITHER SO RAPIDLY AS TO CONVERT THE MELT TO A GLASS WHICH UPON APPROPRIATE HEAT TREATMENT UNDERGOES NUCLEATION AND CRYSTALLIZATION OF THE FERRITE, OR AT A RATE SUCH THAT DEVTRI- FICATION AND FERRITE CRYSTALLIZATION OCCURS DURING COOLING. BOTH PROCEDURES RESULT IN A BORATE-RICH MATRIX CONTAINING THE CRYSTALLIZED FERRITE WHICH CAN BE EASILY RECOVERED SEPARATELY FROM OTHER MATRIX SUBSTANCES BY FOR EXAMPLE MAGNETIC SEPARATION OR DISSOLUTION OF THE BORATE MATRIX MATERIAL IN A WEEK ACID.
Inventors
- 👤 B Shirk
Bibliographic Details
Claims Analysis
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-13 | 1976-08-14 | 1977-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-13 | 1980-08-14 | 1981-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-13 | 1984-08-14 | 1985-02-13 | $7700.00 | Window Closed / Lapsed |