Interfacial damage in EB-PVD thermal barrier coatings due to thermal cycling

Optical microscopy, acoustic microscopy, and thermal wave imaging techniques were used to characterize the interfacial damage in a thermal barrier coated single crystal superalloy subjected to thermal cycling. The thermal barrier coating (TBC) was applied to the superalloy using electron beam physical vapor deposition (EB-PVD) technique. The EB-PVD system seems to be stable al least up to the temperature of 1000 degrees C for 300 cycles. Thermal expansion mismatch and oxidation between the bond coat and ceramic layer leads to separation at the interface which contributes to overall delamination and spallation. Experimental results suggest that buckling induced delamination is a possible mechanism for spallation. (C) 1997 Elsevier Science S.A.