Method of producing a ferrite with a substantially rectangular temperature-stable hysteresis loop

摘要

1,065,970. Magnetic compositions. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. March 15, 1966 [March 24, 1965], No. 11265/66, Heading H1H. A rectangular-loop ferrite with high-temperature stability is made from a starting composition comprising a mixture of the following oxides (or their equivalent oxide-yielding compounds) : 45-60 mol. per cent Fe 2 O 3 28-38 mol. per cent NiO 5-20 mol. per cent ZnO 0À1-10 mol. per cent CdO 0À05-2 mol. per cent CoO 0À01-2 mol. per cent MoO 3 and/or 0À01-1 mol. per cent V 2 O 5 In preparation the mixture is presintered at 900‹C.-1100‹C., ground, granulated with a binding agent such as cellulose, pressed into core shape, and sintered in an oxygen atmosphere at 1350‹ C.-1600‹ C. After sintering the cores are either quenched, or slow cooled at 50‹ C. to 300‹ C. per hour in an atmosphere of decreasing content. For compositions with a hyper-stoichiometric proportion of Fe 2 O 3 , the cores are subjected to a magnetic annealing at 200‹ C.-600‹ C. in a magnetic field of at least 15A/cm.