Daniel Cornu

High heat flux thermal cycling of FGM thermal barrier coatings using a HVOF gun

The aim of this work was to determine the behavior of multi-layered and FGM structures under high heat fluxes. A direct simulation by the implicit finite difference method was used to predict the transient temperature distribution in each layer of the multimaterials. Experimentally, high heat fluxes were produced using a HVOF gun operated with a methane-oxygen mixture and internally cooled samples. Multi-layered deposits (Copper alloy / MCrAlY / Partially Stabilized Zirconia) were sprayed using a plasma torch under controlled atmosphere (VPS) onto a copper block containing cooling channels for a circulation of water. Transient and static tests were performed with heat fluxes up to 100 MW/m 2 for durations of a few minutes to several hours. Microstructural characterizations of deposits were performed by optical microscopy after thermal tests in order to determine the erosion resistance of the PSZ coating for both cases. Results show a better erosion resistance of the FGM (MCrAlY / PSZ) thermal barrier coating.