Influence of quencher on microstructure and magnetic properties of manganese-zinc ferrites

The effects of quencher after calcination on the microstructure and magnetic properties of manganese-zinc ferrites were investigated by measuring the magnetic properties, electrical resistivity and density. The powder of Mn0.68Zn0.25Fe2.07O4 composition was prepared by adopting the conventional ceramic technique. Toroidal cores were sintered at 1350 °C for 4 h in atmosphere controlled by using the equation for equilibrium oxygen partial pressure. The fracture surface micrographs of samples were observed by scanning electron microscope. The results show that the inner stress of calcined powder increases, abnormal grains of ferrite grow up, initial permeability goes down and power losses of ferrite rise with the increase in quenching temperature, and the microstructure and magnetic properties of manganese-zinc ferrites can be improved with the gradual cooling of calcined powder to room temperature (25 °C).