Study Of The Frequency Characteristics Of High Permeability Mn-zn Ferrite Material

In this dissertation, high permeability Mn-Zn ferrites have been prepared by the mixed-oxide route,using Mn3O4, Fe2O3 and ZnO as the raw materials.And in this dissertation we study deeply on the preparation technology and mechanism of high initial permeability MnZn ferrite with better stability of which the initial permeability was 10000. The raw materials , the composition , the time of milling, the calcining temperature, the different additives,the sintering temperature and the sintering parameters were investigated.The result showed : It was advantaged to obtain high initial permeability MnZn ferrite with stable frequency characteristic using high-purity raw materials; In order to obtain MnZn ferrite with high properties,we must control strictly the composition; It could improve the properties of MnZn ferrite by optimizing calcining temperature. The lower calcining temperature made the permeability higher, and the higher calcining temperature could promote the frequency characteristic of permeability; We chosen the right time of milling according to the requirement of power diameter; In order to improve the properties of MnZn ferrite, it is necessary to add effective additives.In this dissertation, the influence of Bi2O3,MoO3,K2CO3,Co2O3 were investigated;The sintering temperature ,the time of heat-retaining and sintering parameters were the key factors of preparing high permeability MnZn ferrites. The right sintering temperature and sintering parameters are the essential guarantee of nicer microstructure and composition. Thinning the crystal grain and increasing the center vent are effective approach to raise the limiting frequency of high permeability MnZn ferrite.Through large quantities of experiments, we made progress in raising limiting frequency of high permeability MnZn ferrite. We prepared the broad band MnZn ferrite of which the initial permeability was 10000. The initial permeability dropped no less than 20% at the frequency of 300 kHz . And the material have the same properties as T38 of EPCOS .