| 摘要 |
959,643. Magnetic compositions. PHILIPS ELECTRICAL INDUSTRIES Ltd. Jan. 2, 1963 [Jan. 5, 1962], No. 260/63. Heading H1H. A method of manufacturing a magnetic core having a substantially rectangular hysteresis loop and comprising a ferromagnetic mixed ferrite, comprises mixing powdered metal oxides (or oxide-yielding compounds) according to the proportions 2-20 % mol. Li 2 O, 0.5- 45 % mol. NiO, 50-85 % mol. Fe 2 O 3 , 0-3 % mol. ZnO, and 0-8 % mol. CuO, compressing into shape, and sintering in air or air plus oxygen at a temperature between 1200 ‹ and 1400 ‹ C. A presintering step may be included. After sintering the mixture may be cooled by one of two schedules : (a) it may be cooled at a rate less than 30‹ C. per minute to a temperature which is 100‹ to 600‹ C. lower than the sintering temperature and then quenched; or (b) it may be cooled at a rate greater than 30‹ C. per minute to such a temperature, held at this temperature for at least 5 minutes, and then quenched. A magnetic memory element formed using the core has properties which are more stable with temperature variation. |
