Detecting the erosion of atmosphere-plasma-sprayed thermal barrier coating system using luminescent multi-sublayers

Abstract Erosion can cause the progressive material loss of thermal barrier coating system (TBCs), raising a challenging problem when gas turbine engines operate in extreme conditions. Therefore, detecting the erosion of coatings plays a crucial role in health monitoring of TBCs. In this work, atmosphere-plasma-sprayed (APS) TBCs specimens were fabricated with five different embedded luminescent sublayers (YSZ:Eu, YSZ:Tb, YSZ:Dy, YSZ:Er, YSZ:Sm, each is 50 μm thick) in the ceramic top coat for each TBCs specimen. To accelerate the erosion rate for detection purpose, a specially designed erosion testing machine was employed in the experiments. In addition, we developed a device to capture the distinctive emission of the exposed luminescent sublayers after erosion and thereby proposed an optical method to detect the erosion in the TBCs. For the specimens embedded with the luminescent sublayers, the size and depth of the eroded area were efficiently determined by the luminescence imaging with a relatively high accuracy.