Nazik Aslan, Malte Bierwirth, Alfred Weber
Clausthal University of Technology, Clausthal-Zellerfeld/Germany

Metallic powders are widely considered as important starting materials in many manufacturing processes, e.g. joining processes, additive manufacturing, coating, etc. The challenge in the field of manufacturing via metallic powders is that the particle surfaces are covered by an oxide layer during the process, even when handling in the inert gas environment, as a consequence of trace amounts of oxygen. On the one hand, these oxide layers prevent progressive corrosion in the materials, on the other hand, they can cause damages through their irregular manner.

The goal of the project is to understand the interaction of plasma-activated reducing gas species with the surfaces of gas-borne particles during their deoxidation and the technical implementation of powder deoxidation on a laboratory scale.

To achieve this aim, dielectric barrier discharge (DBD) systems were constructed in miscellaneous geometries and integrated into various reactors in order to deoxidize the particles completely. In a first approach, the DBD species were transported to the powders within a fluidized bed. By exploiting the use of this tailored method, we were able to deoxidize the powders under a particular atmosphere. Nevertheless, since the active species in DBD plasma lose their activity until they reach the powders, the species are not optimal for deoxidizing anymore.

Therefore, to enable the complete deoxidizing of powders, a DBD construction was customized, and the powders are introduced into the active DBD species taking into account their short life span. Because of these reasons, a fall reactor is used for the deoxidation process.

The different powder deoxidation concepts and the achieved results will be presented.

This project is funded by the DFG, German Research Foundation.