A model of the interface between plasma jet simulation and the simulation of coating formation during atmospheric plasma spraying (APS)

Abstract

The atmospheric plasma spraying (APS) process can be divided into sub-processes, which are simulated by different numerical methods. The balance equations of momentum, mass and energy of the plasma jet are solved numerically by applying the finite volume method (FVM) using a CFD (Computational Fluid Dynamics) software tool. On the other hand the solution of the thermo-mechanical problem of the coating formation on the substrate is estimated using the finite element method (FEM). The movement of the plasma jet above the surface of the substrate during the spraying process causes a time dependent boundary condition for the FEM-analysis. The heat transfer from the plasma jet to the substrate has to be taken into account. There is also a mass and heat transfer of heated particles to the substrate surface, which is responsible for the formation of the coating. Not only the plasma jet influences the boundary conditions of the coating formation, but the substrate is also a boundary for the plasma jet. This has to be considered during the plasma jet simulation, as well. This article describes the physical and mathematical background of the plasma jet/substrate heat transfer interface model, the implementation in the overall simulation process and its use in the simulation of the formation of a thermal barrier coating (TBC) made of partially yttria stabilized zirconia on a turbine blade during atmospheric plasma spraying.