Incremental metal-powder solidification by localized microwave-heating and its potential for additive manufacturing

This paper presents a concept of solidifying small quantities of metal powders in an additive manner, using localized microwave heating (LMH). The experimental results show solidification of metal powders in forms of spheres and rods (of ∼2 mm diameter) and extension of these rods by adding batches of powder and consolidating them locally as building blocks by LMH. A theoretical model applied for the LMH interaction with metal powders attributes a magnetic heating effect also to powders made of non-magnetic metals, due to eddy currents. The experimental observations and numerical results also suggest that micro-plasma discharges between the powder particles initiate their heating process. The additive LMH approach presented here is intended to extend microwave sintering capabilities, mainly known in volumetric molds, also to applications in the framework of rapid prototyping, additive manufacturing, and 3D-printing. The potentials and limitations of the powder solidification by LMH are discussed in this view.