Research On The Preparation Technology Of R12K High Permeability MnZn Ferrites

With the progress of society, more and more electronic products develop tominiaturization, lightweight, energy-saving and environmental protection. The size ofthe device determines the size of the electronic system. The smaller the device, thelower energy loss and the smaller the space is taken. In order to achieve the sameinductance, fewer winding turns is required by the magnetic materials with highpermeability, which can effectively reduce the loss of the conductor and the volume ofthe device. So the miniaturization and lightweight of the devices require the ferrite withhigh permeability. Furthermore, the electromagnetic interference （EMI） must beovercomed in today’s electronic products. The soft magnetic ferrites with highpermeability and high impedance can absorb the interference signals, solving theproblems of EMI. Because of the stringent environment in the process of preparing highpermeability materials, the researchers at home and abroad pay attention to the lab andproduction simultaneously. In this dissertation, high performance MnZn ferrites wereprepared by oxide ceramic process in industrial equipment. The effects of the rawmaterials, composition, different additives, second milling time, calcining and sinteringtemperature were investigated. The results show that:The high purity Fe₂O₃can prepare MnZn ferrite with high initial permeability（μi）and superior magnetic properties. When the formula is Fe₂O₃: ZnO: MnO=51.5：22：26.5mol%, a higher permeability material obtained. Through the study of additives, theCaO can improve the frequency and temperature characteristics of the material,especially, the impedance characteristics. The MoO₃can significantly increase the initialpermeability of the ferrites. The V₂O₅can improve the initial permeability and themagnetic properties. The Nb₂O₅decreases the initial permeability, but increases the Qvalue. In the preparation process, the calcining temperature and second milling timeaffect the activity of the powder, which controls the grain growth, and improves themicrostructure. Sintering temperature affects the grain growth through the solid phasereaction velocity. So, the ferrites with large grain size, uniform and dense microstructure can be obtained by proper preparation process （the calcining and sintering temperature,the second milling time）.The high permeability MnZn ferrite with good frequency characteristics can beprepared by proper formula and preparation process. When frequency is10kHz, μireaches to12000，and when the frequency increases to200kHz, μiremains10000. Thematerial has good temperature and impedance characteristics.