Computational Study on the Effect of Gas Composition on Particle Behavior and Coating Oxidation in Vacuum Plasma Sprayed MCrAlY Coatings

This study investigates the effect of Ar-H₂ gas composition on vacuum plasma spray (VPS) of MCrAlY bond coats using computational modeling. The plasma jet is simulated with an OpenFOAM-based flow solver, and the resulting flow field is used as input for particle tracking in ANSYS Fluent to predict in-flight particle temperature and velocity in a low-pressure chamber. As H₂ flow rate increases, particle temperature rises and velocity decreases due to higher plasma enthalpy. These changes affect the formation of oxide layers between splats in the coating. The simulation results are compared with SEM cross-section measurements of intersplat oxide thickness, showing good agreement. This work provides useful insights for selecting gas compositions to improve MCrAlY coating quality in thermal barrier coating applications.