Prime Material for Plasma-Facing Components

Due to the same properties that make it a prime material for plasma-facing components (PFCs), tungsten (W) is difficult to work into small powder form, which is necessary for its use in additive manufacturing (AM) techniques. Commercially available W powders have a large size distribution, even if sold as certain sized powders [1]. Further size distribution narrowing of micron-sized commercial W powder requires more energy than can provided by traditional ball milling methods. Although nano-sized powders can be obtained by ball milling, milling time increases exponentially as powder size decreases [2]. By providing large amounts of energy in a short time span, microwave induced plasmas (MIPs) can overcome this time hurdle, allowing the production of nano-sized W powder with narrow size distribution in bulk.

This study seeks to manufacture porous W structures utilizing cold-spray AM using plasma-treated commercial powders as the feedstock. The powder is subjected to a 2.45-GHz MIP torch under vacuum using argon as both process and shield gases. Plasma characterization is performed by optical spectroscopy, and the effect of the plasma treatment on powder size distribution is assessed by laser diffraction particle size analysis. Powder purity characterization is performed by XPS at the IGNIS-2 facility at Penn State. Potential for powder to be used as liquid metal PFC material is determined by microhardness and porosity testing.