The Numerical Analysis of the Trajectory and Landing Location of YSZ Droplets Impinging the Microtextured Substrate

Abstract

AbstractThis work considers the possibility of controlling the thermally sprayed TBC columnar microstructure using metallic bond coat microtexturization prior to ceramic top coat spraying. Such pretreated bond coat has been modeled to investigate the influence of the substrate topography on the behavior of the plasma stream and the resulting movement of the feedstock particles in the closest proximity of the substrate. The analysis considered the microscale computational domain. It was extracted from the entire spraying domain and located in the microtextured substrate boundary layer at three different distances from the plasma jet centerline. Advanced flow models were used here to define the plasma jet/feedstock droplet interaction and the heat flux to the substrate. YSZ feedstock was modeled using the discrete phase model with a DPM source and particle drag law introduced to the governing equations. Then, the TBC deposition conditions were investigated considering the effect of the distance from the plasma jet centerline. It was concluded that the intensity of the shadowing effect determines the columnar TBC build-up mechanism depending on the droplet landing location on the microtextured substrate. The motivation behind this study was to model and investigate the influence of the bond coat microtexturing on the behavior of the feedstock particles in the substrate boundary layer. This opens the possibility of better understanding the mechanism of the coating build-up, strictly controlling the microstructure of such TBCs, and improving their overall performance.