Photothermal and Photo Acoustic Investigation of Zirconia Coating Delaminations

Abstract

<p>Plasma sprayed ZrO2 coatings on ferritic steel with artificial adhesion defects were investigated using multiple photothermal and photoacoustic methods. The delaminations were produced by preventing the sand blasting of sections of the surface prior to applying the coating. Case study comparisons between an IR-camera/ flash lamp system, line scanning IR-imaging, pulse photoacoustic imaging, and thermal wave interferometry were performed. The methods offer a varying level of contrast for the defects depending on their relative sensitivity, resolution, and operating principle.</p>