Cooling Rate Effects on the Microstructure, Magnetic Properties, and DC Superposition Behavior of NiCuZn Ferrites

This study investigated the cooling rate effects on the magnetic properties of NiCuZn ferrites. A copper-rich phase segregated near the grain boundaries during sintering was observed. The amount of copper-rich precipitates depends strongly on the cooling rate and decreases with decreasing cooling rate. The quenched sample exhibited superior initial permeability and DC-bias-superposition characteristics due to the highest saturation magnetization and a thick nonmagnetic second phase segregated at the grain boundaries. A NiCuZn ferrite with superior initial permeability and DC superposition characteristics can be obtained by controlling the cooling rate to adjust the copper-rich precipitate thickness at the grain boundaries.