Magnetic ferrite of high maximum permeability and high curie point

摘要

689,292. Magnetic compositions. STEATITE RESEARCH CORPORATION. Sept. 17, 1951 [Oct. 7. 1950], No. 21809/51. Class 38 (ii). A magnetic ferrite composition has the formula x(NiO,ZnO,CuO) y Fe 2 O 3 in which x : y is between 0.98 : 1.02 and 0.95 : 1.05 and the CuO forms 1.25 to 7 per cent by weight. Copper oxide, carbonate, or basic carbonate is mixed with the right proportions of the other powdered oxides, milled, in water, dried, powdered, mixed with a little binder such as flour, gum or wax emulsion, pressed, fired at about 2400‹ F. for several hours in air and cooled. The initial permeability is between 650 and 1200, maximum permeability exceeds 4000, saturation flux density is about 4000 gauss, coercivity is less than 0.25 oersted, brine point is between 120‹ and 190‹ C., residual magnetism is not more than 2000 gauss, and the hysteresis and other losses measured by the coefficient a of the Legg equation and below 15 Î 10SP-6/SP. pressing, the powdered oxides may be separated into several grain sizes, the parts being mixed in selected proportions. Specification 677,418 is referred to.