Electromagnetic field effects in the microwave sintering of electrically conductive powders

Rapid sintering of compacted electrically conductive powders under heating by intense microwave radiation is investigated within a one-dimensional simulation model. The model accounts for the effective dielectric and magnetic properties of the powder material, electromagnetic field distribution, heat losses by thermal radiation, and densification. It is demonstrated that metal powders with insulating boundary layers on particles have low dielectric and magnetic losses, which results in a resonant character of microwave absorption. The influence of the interparticle contacts is investigated by introducing an effective electrical conductivity of the boundary layers, which can depend on the density. It is demonstrated that the losses in the boundary layers can stabilize the microwave heating process, facilitating rapid densification.