| Most of electronic devices are required to operate normally at complexconditions,high temperature for example,and their stable working temperature ishigh（100℃120℃）,meanwhile, improve the saturation magnetic induction of the core,keep the core work below the saturation magnetic induction, can avoid core burned bylosses increases.In this dissertation, MnZn power ferrites with high saturation magneticinduction （Bs）and low losses（Pcv）at high temperature were prepared by conventionaloxide ceramic process. In order to preparing high saturation magnetic induction（Bs）,high Curie temperature （Tc） and low losses（Pcv）MnZn ferrites, the effects of maincompositions, additives and sintering temperature on the microstructure and magneticproperties of MnZn ferrite were investigated.The results show that:In the aspect of main composition studying：based on Fe-Mn-Zn ternary systemmaterial, when Fe2O3content is in the range of50mol%56.0mol%,the initialpermeability first increases and then decreases, the saturation magnetic induction asloincreases monotonously. By substituting with Li+and Ni2+ions, the initial permeabilityand the saturation magnetic induction decrease monotonously. The best proportion offour oxide compositions is Fe2O3: MnO: ZnO: NiO=54mol％:38.5mol％:6.5mol％:1mol％.In the aspect of additives doping studying: based on Fe-Mn-Zn-Ni quarternarysystem material, when doped with CaCO3, the microstructure and magnetic propertiesof MnZn ferrites improve significantly, the saturation magnetic induction first increasesand then decreases, the total losses first decreases and then increases. When doped withTiO2, accelerate the speed of grain growth, the saturation magnetic induction increases,the total losses decreases. The appropriate amount of TiO2is0.2wt%. By doped withV2O5, the saturation magnetic induction first increases and then decreases, the totallosses first decrease and then increase. When doped with0.03wt%V2O5, MnZn powerferrite possesses the highest initial permeability and saturation magnetic induction, andthe lowest power losses. By doped with Bi2O3, the saturation magnetic induction firstincreases and then decreases, the total losses first decrease and then increase. The appropriate amount of Bi2O3is0.03wt%. By doped with SnO2, promoted the graingrowth, increases the saturation magnetic induction, and decreases the total losses.Based on Fe-Mn-Zn-Ni quarternary system material, at the temperature range of13201380℃, with sintering temperature rised, the saturation magnetic induction firstincreased and then decreased, the total losses first decreased and then increased. |
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