Study On The Preparation Of Mn-Zn Soft Magnetic Materials For Automotive Electronics From MnZn Ferrites Wastes

Mn-Zn ferrites is an important functional material in industry, electronic information and civil fields, widely used in automobile electronics, home appliances, computer, network technology and other industry. In the manufacturing process,10%-20%Mn-Zn ferrites wastes are inevitably produced. At present, the treatment method of these MnZn ferrites waste is preserved. If high performance ferrites can be made from these wastes, it will create huge economic and environmental benefits. In the subject, Mn-Zn soft magnetic materials for automotive electronics Charging System have been prepared by ferrites process, using the co-precipitation powders as raw materials, which obtained from the ferrites wastes by hydrometallurgy method. The effect of pre-sintering, doping and milling, sintering to the ferrites magnetic properties was researched. The main contents and results are as follows:The effect of pre-sintering temperature was studied in this paper. The result showed that pre-sintering had a significant effect on the composition and structure of the ferrites powders. With the pre-sintering temperature increasing, the grain of the ferrites powders increased and the grain size became well-distributed. But over-increasing would result in agglomerate and the powder shape would become irregular. The optimum pre-sintering temperature is900℃.The influence of additives and adding dose on the properties of Mn-Zn ferrites was researched. Studies showed that the proper addition of CaCO3, Nb2O5, SiO2, Bi2O3, V2O5, SnO2and TiO2could effectively improve the microstructure and magnetic properties of Mn-Zn ferrites. The optimal doping combination is CaCO30.02%+ZrO20.02%+SnO20.02%.The effect of sintering time, atmosphere and sintering temperatures on the magnetic properties and microstructure of Mn-Zn ferrites was studied, the result showed that high permeability ferrites owning large grain, straight grain boundaries and few pores could obtain with suitable sintering temperature. There were differences in grain size, uniformity and the number of pores, and morphology with different sintering time, eventually led to the magnetic properties of Mn-Zn ferrites difference. The sintering atmosphere could effect the phase composition and magnetic performance of Mn-Zn ferrites, certain balance atmosphere must be controlled for high properties Mn-Zn ferrites. The optimum conditions of sintering process are sintering temperature of1320℃, holding temperature time of4.0h and sintering atmosphere of5.0%partial pressure of oxygen, respectively.After optimizing conditions obtained from above process, the comprehensive experiment was successfully processed and the high performance Mn-Zn ferrites materials for automotive electronics Charging System has been prepared from the ferrites wastes, which the initial permeability reached2312and power loss per unit volume of Pcv was609kW·m-3. This ferrites has the same properties as PC44of TDK Corporation.