Effect of Process-Gas Composition on In-Flight and Deposition Characteristics of Atmospheric Plasma-Sprayed Ni Particles

In-flight particle characteristics, such as velocity and temperature, are of great importance when utilizing atmospheric plasma spraying because they determine the coating quality. Here, a numerical model that could predict the arc plasma and in-flight particle information was developed, and experiments were conducted to support the simulation results. Local thermodynamic equilibrium was assumed for the computational model of arc plasma, and the interaction of arc plasma and in-flight particles was calculated by tracking using the Lagrangian approach. Among the various process parameters, the composition of the process gas (Ar and H 2 ) was controlled. The simulation results showed that a difference in the process-gas composition drastically affected the thermophysical properties of arc plasma for heat transfer to the in-flight Ni particles. A single-particle impact test and coating analysis also revealed that a high hydrogen ratio resulted in high deposition efficiency, low porosity, high oxidation, and intimate inter-splat bonding, with a high degree of droplet heating. Graphical Abstract