Research of in situ modified PS-PVD thermal barrier coating against CMAS (CaO–MgO–Al2O3–SiO2) corrosion

Feather-like columnar structured 7YSZ thermal barrier coating (TBC) was prepared by plasma spray-physical vapor deposition (PS-PVD). An aluminum (Al) film was deposited on the TBC surface by magnetron sputtering. The Al-deposited TBC was vacuum heat-treated at 665 °C, 808 °C and 900 °C for 1 h separately. Then an α-Al2O3 layer was observed on the top of 7YSZ coating, which resulted from in situ reaction of Al and ZrO2 at high temperature under vacuum condition. The microstructure evolution and phase composition of the TBC were characterized by FE-SEM and XRD respectively. The CMAS (CaO–MgO–Al2O3–SiO2) corrosion property of as-sprayed and treated Al-deposited TBC was compared, which was conducted at 1200 °C for 24 h. The results show that the Al-deposited TBC after vacuum heat treatment have better CMAS corrosion resistance than the as-sprayed TBC.