Production of a manganese-zinc ferrite used as cores in network transformers in telecommunications comprises a maximum temperature holding step for combustion, and a cooling step carried out in a nitrogen atmosphere

摘要

Production of a manganese-zinc ferrite comprises a maximum temperature holding step for combustion; and a cooling step carried out in a nitrogen atmosphere. The nitrogen atmosphere temperature change T in the cooling step is below 1150 deg C and at least 1000 deg C. The extent of cooling is given by the equation: T = (V1 + 1450)/1.5 (where, T = the nitrogen atmosphere temperature change in deg C; and V1 = the extent of cooling in deg C/h from T to below 900 deg C). Preferred Features: The ferrite contains 52-55 mol.% iron oxide and 7-12 zinc oxide with a balance of manganese oxide, 60-140 ppm silicon dioxide, 350-700 ppm calcium oxide and 100-350 ppm niobium oxide.