Demirskyi D. Sintering kinetics and sintering mechanisms for materials with various nature of microwave energy absorption.

The aim of this study is the in-depth analysis of the kinetics on the initial stage of sintering during microwave heating, those include the neck growth kinetics and interparticle shrinkage of the spherically shaped particles, and the investigation of the densification kinetics of compacts from spherically shaped powders. Those have been conducted for materials with different nature of microwave energy absorption. Therefore, in present work the kinetics of the initial and intermediate stages of microwave sintering of metals and ceramics has been studied. The mechanism of mass transport thus was identified for the initial and intermediate stage of microwave sintering, those are crucial for formation of the general theory of the microwave sintering process and may be used for further optimization of the microwave sintering process. The comparison of the neck growth kinetics and densification kinetics for spherical shaped powders has been performed for microwave and conventional sintering. An anomalous neck growth rate has been revealed during microwave sintering of copper, nickel, iron and fused tungsten carbide powders. The later is caused by the formation of the melted regions during the neck growth/formation processes between spherical shaped particles and have been confirmed by the apparent diffusion coefficients and the activation energies observed.