Rumpling induced by thermal cycling of an overlay coating: the effect of coating thickness Original Research Article

Initially flat NiAl-based overlay coatings on a Ni-base superalloy substrate develop surface undulations when cyclically oxidized at high-temperatures. The effect of the coating thickness on the amplitude and wavelength of the undulations is described. The amplitude, after 100 one-hour cycles to 1150 °C in air, appears to have a maximum at intermediate thicknesses between 100 and 150 μm whereas the effective wavelength increases with the coating thickness.