Corrosion Behavior and Failure Prediction of YSZ Coatings Under CMAS Attack

Abstract

In aeroengines, thermal barrier coatings (TBCs) are usually utilized to protect the hot components from hot gases. The ability to predict the TBC failure is crucial to avoid economic losses. In this study, plasma-sprayed 8 wt.% yttria-stabilized zirconia (YSZ) coatings were subjected to corrosion by calcium–magnesium–aluminosilicate (CMAS, 33CaO–9MgO–13Al2O3–45SiO2) glass at 1250 °C. After the test, two morphologies were observed on the coating surface. At the sample edges, the coating underwent over-sintering because of the locally high temperature: the molten glass easily penetrated the YSZ layer and reacted with it; and iron spinel was detected on the surface. In the sample central region submitted to a relatively lower temperature, a dense layer consisting of both CMAS glass and YSZ was formed. The analysis of the self-luminescence of the YSZ coating after corrosion revealed the presence of sintered regions on the coating surface, which increased as the corrosion temperature increased. This came with a decrease in the coating luminescence. This study shows that the self-luminescence properties can be used to monitor the degree of corrosion and predict the failure of the coating.