Powder production via electrohydrodynamic-assisted molten metal jet impingement into a viscous medium

In this paper, a novel method for preparing metal powder with the aid of electrohydrodynamic (EHD) force is introduced. A pneumatic based atomization apparatus was constructed for this study. Solder melt jet is injected from a 250 μm ID nozzle onto a viscous medium (transformer oil). As a result of jet impingement and penetration into the oil, the melt jet disintegrates into micro-sized droplets and ligaments by a combination of the natural jet breakup phenomenon and EHD atomization. Due to the presence of electrostatic forces, the disintegrated droplets and ligaments repel each other and therefore particle coalescence and agglomeration is minimized in this method. The breakup was captured with a high speed camera. The morphology and structure of the obtained powders were investigated using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), respectively. Morphology of the particles was controlled by varying the oil temperature and the EHD voltage. Structure investigations show that a decrease in particle size leads to an increase in interior microstrain. Also, interior microstrain increases by decreasing the oil temperature. The main advantage of the developed method is to produce fine powder with controlled characteristics such as size, size distribution, morphology and structure.