Evaluation of ZrO2–24MgO ceramic coating by eddy current method

A novel study was carried out using eddy current technique for non-destructive evaluation of Thermal Barrier Coatings (TBC). For this purpose, zirconium oxide, stabilized with magnesium oxide as a top-coat, and Ni-5Al as a bond-coat were air plasma sprayed onto a nickel base alloy substrates. Microstructure and phase changes were observed during thermal treatment. Formation of nickel-oxide was noticed during the experimentation. The values of eddy current and the phase-angle changes, were correlated with the micro-structural and metallurgical phase changes, observed at the interface of bond-coat and top-coat.