W-Cr Coatings for Plasma Facing Components in Tokamaks by Cold Spray and RF-ICP

Due to its favorable properties such as high melting point, high thermal stress resistance, high thermal conductivity, as well as low erosion (i.e., high energy threshold to suffer from sputtering) and low tritium retention, tungsten and its alloys are promising armor candidates for plasma facing components (PFCs) in future fusion reactors such as tokamaks. The processing of PFCs via traditional methods is complicated by tungsten’s inherent properties such as brittleness (high DBTT), CTE mismatch with materials used in tokamaks (Cu, steels), susceptibility to grain growth, susceptibility to oxidation at above 500 °C, or poor weldability and machinability. Given these factors, the attention has recently shifted from metallurgy routes to powder/additive manufacturing alternatives.

In our work, two technologies are presented for consolidation of W and W-10Cr layers: both cold kinetic spraying (CS) and radio frequency inductively-coupled plasma (RF-ICP) are capable of overcoming the associated production problems and fabricate the plasma-facing layers directly on structural parts, without the need for joining. Importantly, both achieve this without oxidation of the metals. The final properties were studied using SEM, XRD, as well as mechanical and thermal analyses.