High temperature behavior of a diffusion barrier coating evolved from ZrO2 precursor layer

Abstract The zirconia (ZrO 2 ) as a precursor layer for the diffusion barrier coating (DBC) was deposited by electron beam physical vapor deposition (EB-PVD) between the Rene N5 superalloy substrate and NiCrAl coating. The high temperature exposure for the N5/ZrO 2 /NiCrAl system was carried out at 1000 °C for 5 h, 100 h and 200 h in atmosphere to investigate the structure evolution of the ZrO 2 precursor layer and the elements interdiffusion of the system compared with the N5/NiCrAl system. The results showed that a sandwich structural DBC (α-Al 2 O 3 /rich-Zr/α-Al 2 O 3 ) was formed through redox reaction between zirconia and aluminum under high temperature, leading to the transformation of N5/ZrO 2 /NiCrAl system into the N5/DBC/NiCrAl system. It was found that the sandwiched DBC could effectively suppress the interdiffusion of elements compared to the N5/NiCrAl system.