Reactive plasma spraying of supersaturated tungsten super-hard Ta-Hf-W-C solid solution coating

A supersaturated tungsten Ta-Hf-W-C solid solution coating is successfully prepared by a reactive plasma spraying. The reaction process and solution behavior of TaC-HfC-WC-C composite powder during induction plasma spheroidization (IPS) and vacuum plasma spraying (VPS) are described. Compared with the direct spraying, the coating made by IPS-VPS multi-stage plasma heating process has lower porosity and better composition uniformity. The highest hardness obtained by nanoindentation can reach up to 43.3 GPa due to solid solution strengthening. This work provides a new method and a potential material for thermal spraying super-hard coatings.