Effect of Al-deposition on erosion resistance of plasma sprayed thermal barrier coating

A columnar Al film was firstly deposited on the top of 7% Y2O3-stabilized zirconia (7YSZ) ceramic coating in thermal barrier coating (TBC) system by magnetron sputtering. A vacuum treatment was then carried out at 700 degrees C for 1 h and 900 degrees C for 5 h to improve the erosion resistance of Al-deposited TBC. A alpha-Al2O3 layer was in situ synthesized on the top of 7YSZ coating via vacuum heat treatment. The microstructure evolution of Al-deposited TBC illustrated that a loose surface-layer and a dense sub-layer formed on the top of 7YSZ coating after vacuum treatment. The phase structures of the as-sprayed TBC and the Al-deposited TBC after vacuum heat treatment were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM) assisted with focused ion beam (FIB). Particulate erosion resistances of the as-sprayed TBC and treated TBC were compared at room temperature. In addition, erosion mechanism and schematic diagram were proposed. The results show that the Al-deposited TBC after vacuum heat treatment has better particulate erosion resistance than the as-sprayed one.