A process for the preparation of soft magnetic, sintered manganese-zinc-ferrous ferritlegemer, in particular ferrite rings for use in high-frequency technology.

摘要

1,004,748. Magnetic compositions. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. Aug. 4, 1964 [Aug. 5, 1963], No. 31511/64. Heading H1H. A manganese-zinc ferrite is made by a process which includes a complex sintering schedule to achieve the desired oxygen content of the final material. In particular, a method of making a MnZn ferrite comprises presintering a mixture of oxides or equivalent compounds the mixture consisting of 24À5-28À5mol. %MnO, 53-54 mol. % Fe 2 0 3 and balance ZnO, cooling and pulverizing the presintered product, forming a shaped body, sintering between 1370‹ and 1430‹ C. in an atmosphere containing 95% O 2 for between 15 minutes and 3 hours, then cooling the sintered body, initiating a gradual reduction of the oxygen content when the body is between 1250‹ and 1310‹ C., continuing the reduction of oxygen so that at 1150‹ C. the atmosphere contains less than 0.2% 0 2 and cooling to room temperature in this atmosphere, providing means for controlling the evaporation of zinc (e.g. by placing in a ferrite pot of the same composition as the body, or by adding zinc vapour to the atmosphere), heating the body to between 1250‹ and 1310‹ C. in an atmosphere containing between 0.05 and 1% O 2 and maintaining this for 5-10 hours, and cooling to room temperature while the oxygen content does not exceed 0.1%.