Microwave Sintering Study of NiCuZn Ferrite Ceramics and Devices

Studies on sintering behavior, including densification and grain growth of NiCuZn ferrite ceramics were carried out in a microwave field of 2.45 GHz. Compared to conventional sintering, the shrinkage curves of a NiCuZn ferrite system processed by microwave sintering shifted toward approx 100 C lower temperatures. The effective activation energy for diffusion under microwave sintering was lower than those controlled under conventional sintering. In addition, pressed toroidal inductors and multilayer chip inductors (MLCI) have also been sintered by microwave processing. Although heating rate of the microwave sintering was faster than that of the conventional sintering, microwave sintered samples were without any visible cracks. Total sintering time was reduced in comparison with conventional sintering. In both the sintered toroidals and MLCI samples, comparable magnetic properties were obtained. 38 refs.