Off-line and On-Line Metal Powder Characterization by PDA

: Brenn, G.; Raimann, J.; Wolf, G.; Domnick, J.; Durst, F.

Abstract
Modern metal powder processing techniques have a continuous demand for decreasing the mean particle size of powders and increasing quality in terms of, e.g., powder particle surface structure and morphology. The industrial processes of gas or inert gas assisted atomization (IGA) of molten metals must therefore be optimized to yield these required high quality powders at competitive prices. In the present work it was attempted to reach this optimization by two steps: first, the search for a deeper understanding of the IGA process through detailed off- and on-line PDA measurements and, second, on-line process control for the adjustment of the dominant process parameter, the atomizing gas pressure, to an optimized level. It was found that a droplet velocity measurement at a single specific location inside the molten metal spray of IGA is sufficient to characterize the mean droplet diameter of the whole spray and, hence to predict the essential characteristics of the metal powder produced.