Modeling of the APS Process: from the Arc to the Coating Effective Properties

Atmospheric Plasma Spray is widely used for tens of years to elaborate protective coatings on parts for several applications. However, our understanding of the APS process can still be improved, requiring a fine modeling of the process in parallel with some corresponding experiments. In the present work, a complete series of models was applied to reinforce our knowledge of the process: the case an alumina coating was considered. A 3D CFD model was first used to study the internal arc within the torch. Interactions between the external plasma jet and the injected particles were then computed in a second step. At this level, the predicted in-flight particle characteristics were compared with some corresponding measurements recorded with the DPV 2000 diagnostic tool. A third model was then applied to investigate the particle flattening on the substrate/coating material. SEM pictures of coating cross-sections were then captured and a last model was finally applied to estimate the coating effective thermo-mechanical properties based on calculations performed directly on the SEM micrographs. This set of models allows investigating the APS process from the DC arc within the torch to the coating properties.