Influence of microstructure optimization on magnetic and thermal properties of MnZn ferrite

For the industrial preparation of MnZn ferrite with high magnetic permeability and low magnetic loss, three-phase asynchronous machine was used to extrude MnZn ferrite magnet with large aspect ratio, and the final high-performance MnZn ferrite was obtained via subsequent tube furnace high-temperature sintering method. The effects of sintering temperature and oxygen partial pressure on the evolution of microstructure, and the electromagnetic and thermal properties for the MnZn ferrites were discussed systematically. The results showed that with the increase of the sintering temperature and oxygen partial pressure, both the effective permeability and quality factor show a trend of first increasing and then decreasing, and the highest values of them were obtained when the sintering temperature and oxygen partial pressure were 1260 °C and 3% oxygen partial pressure, respectively. The thermal conductivity exhibited a parabolic shaped trend with the increase of the oxygen partial pressure, and achieved maximum value at 3% oxygen partial pressure, while it decreased as the temperature increases further. The total magnetic loss of MnZn ferrite had a valley bottom temperature. As the oxygen partial pressure increased, the valley bottom temperature shifted to a higher temperature. The MnZn ferrite prepared with 3% oxygen partial pressure had the lowest total loss at 90 °C.