Structural evolution of Al-modified PS-PVD 7YSZ TBCs in thermal cycling

Abstract

Feather-like columnar 7YSZ thermal barrier coatings (TBCs) were prepared by plasma spray-physical vapor deposition (PS-PVD). In order to improve the thermal cycle performance of TBCs, Al-modification was carried out with the as-sprayed TBCs. Al film was deposited on the surface of TBCs. Subsequently, the Al-deposited TBCs were conducted with vacuum heat treatment. After that, a dense overlay consisting of α-Al2O3, Al3Zr phases was generated on the TBCs surface due to the reactions of Al and O2, Al and ZrO2. The Al-modified TBCs show a better thermal cycle performance than the as-sprayed TBCs because of the overlay generation. Moreover, the structural evolution of overlay was investigated emphatically before and after thermal cycle testing, showing good phase stability. No crack and spallation were observed in the Al-modified TBCs.