Modeling time-dependent phenomena in plasma spraying of liquid precursors

Abstract

The recently developed plasma spray processes using liquid precursors make it possible to produce finely structured coatings with a broad range of microstructures and, thus, properties. However, coating reproducibility and control of the deposition efficiency are critical to industrial acceptance of these processes. Both depend on time-dependent interactions between the plasma jet and liquid material. Transient and realistic modeling of the liquid spray process may help to increase the understanding of the process. A comprehensive model should involve the formation of the plasma jet inside the torch and the transient specific treatment (break-up, droplet collision, coalescence, evaporation, chemistry) of the liquid material in the plasma jet. If much progress has been recently made on the modeling of the interaction of arc and transverse flow in the plasma torch, further theoretical and experimental research is needed, especially in respect of liquid injection and fragmentation under plasma spray conditions.