Induction Heating Mechanism of Packed Metal Powders

Abstract

The complex permeability was calculated and compared with measured values for packed metal powders, in order to clarify the heating mechanism in the deoxidation process of water-atomized steel powders through induction heating in vacuum.
The calculation was carried out separately on “unsintered” and “completely sintered” packed powders based on different models. The former model restricted eddy currents within individual particles, where the electromagnetic field distribution in an isolated particle was first solved strictly, and then modified in order to take into account the magnetostatic interaction between particles. The latter model assumed the predomination of inter-particle eddy currents and led to the heat generation mechanism similar to that of uniform materials. A more general form for “incompletely sintered” packed powders was obtained as a unification of the above two extremes introducing a parameter for the completeness of sintering.
The calculated results were compared with the measurements in the frequency range of 1∼500 kHz on the unsintered and sintered packed powders of copper and iron with spherical particle shapes. The comparison revealed superior coincidence at various stages of sintering.