Multiple sintering of MnZn ferrites in controlled atmosphere

Abstract

A series of experiments were conducted on multilayer sintering of MnZn ferrite cores in a production type furnace. The cup cores were stacked one over the other, up to ten layers and each loading of the furnace had 3000 cup cores 18×11mm in size. All the electrical characteristics such as permeability, resistivity, eddy current and hysterisis loss, disaccommodation and temperature factor were measured. There was no significant difference between layers in these factors. Experimental data supporting these observations are presented. Production runs were undertaken and the experimental findings were confirmed. It is suggested that the soaking time of one and a half hr and slower cooling rate has helped to attain equilibrium conditions allowing the gases to permeate to all the layers. The variation in electrical characteristics that are evident appears to be due to the inherent limitations in process control.