PURPOSE: To manufacture ferrite in high efficiency at low coat by a method wherein an additive for a crystalline grain boudary insulation is added to a material particles for molding to be baked more than twice.
CONSTITUTION: The material particles mainly comprising 20-30mol% of MnO, 10-25mol% of ZnO and remaining Fe2O3 are mixed, calcinated and fine crushed to be molded furthermore, after adding an additive for a ferrite crystalline grain boundary insulation, the baking step is repeated more than twice. As for the additive for grain boundary insulation, CaO, SiO2, Nb2O5, Ta2O5, In3O3, ZrO2, MoO3, TiO2, Sb2O3 etc., are applicable, while as for the added amount, 100-2000ppm for CaO, 10-4000ppm for TiO2 10-1000ppm for other oxides are preferable. Through these baking steps in plural times, the high permeability can be attained without uselessly raising the baking temperature or baking the material particles especially in a long time.
GOTO SATOSHI
KONO TAKASHI
