Synthesis of nanopowders is carried out with an inductively coupled plasma setup. Dedicated to research activities it is equipped with numerous view ports for process observation, monitoring, and in-situ characterization. The nanoparticles plasma synthesis is based on rapid condensation, also called quenching, of a supersaturated gas phase. The quenching dynamics influence the nanoparticles properties such as size, size distribution and eventually the final chemical composition. The control and understanding of this condensation is of prime importance for guaranteeing the quality of the processed nanopowders.
The high temperatures (10000 K) and moderate velocities (100-200 ms-1) observed in radio frequency (RF) inductively coupled plasmas are particularly suitable for the evaporation of solid precursors. The starting material in our case is thus typically microscale powders that are mostly commercially available and easy to handle in a safe way. Furthermore, the process is performed under a controlled atmosphere (reducing, oxidizing or inert) allowing then the production of a large variety of nanoparticles.
In parallel to scientific and technological investigations, the Health, Safety and Environment (HSE) issues have been evaluated and best practice guidelines have been developed regarding production and manipulation of nanopowders. Particular attention has been also paid to the design of a special filtration unit.
Finally, the thermal plasma can be also used for spheroidizing microscale particles enhancing so their flowability. This is of great interest for additive manufacturing processed based a powder bed.