Debonding study of Ni-base substrate/Pt coatings interfaces using laser shock waves: characterization of the targets and experimental study

This paper presents a set of laser shock debonding experiments performed using two kinds of targets constituted of a Ni-base substrate covered with coatings of platinum several micrometers thick. By applying laser shocks of increasing amplitude with different pulse durations between 600 ps and 3 ns, the decohesion of the coatings was observed above a threshold intensity. Depending on the quality of the interface and on the loading shape and duration, the nature of the damage in the target changed and some cohesive rupture in the substrate was observed in the case of the diffused coating. These experimental data are interpreted by the mechanisms of shock wave propagation in the two layer targets, evidencing the influence of the loading and the thickness of both layers on the laser intensity leading to the debonding. The interest in collecting data on the debonding threshold by laser spallation to validate a numerical criterion able to simulate this decohesion is shown.