Abstract
An experiment has been conducted to clarify the milling effect upon the sintering rate in the LiMInZn ferrite. The ferrite powder was wet-milled by a vibration mill for various times ranging from 2 to 24 hours and the linear shrinkage of the powder compacts during heating was measured. The shrinkage ratios, log (ΔL/L0)100min were obtained by sintering the samples at various temperatures for 100 minutes and they. were plotted against 1/T. This relation has indicated that all linear lines have a knee of gradient at about 750°C. A sample milled for 2 hours has an apparent activation energy for sintering of 13 kcal/mol in the temperature range between 600 and 750°C, and a sample milled for 24 hours has that of 89 kcal/mol. This may be infered that amorphous laver on the surface of the milled particles prevents the densification by the grain boundary diffusion process. Above about 750°C, the sintering has progress at a greater rate in a sample milled for longer hours so that a sintered body of small grain with high density was obtained. The examination of the milling effect on the performances of a memory core has indicated that the signal-to-noise ratio of core output and their mechanical strength are remarkably improved with an increase in milling time, while the switching speed becomes somewhat slower.
