6533b855fe1ef96bd12afd53

RESEARCH PRODUCT

Laser Ultrasonic Testing for Estimation of Adhesion of Al2O3Plasma Sprayed Coatings

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Abstract The aim of the present study was to investigate the possibility of using a laser ultrasonic technique for the estimation of the adhesion of ceramic coatings, deposited onto metallic substrates by thermal spraying techniques. For this purpose, a pulsed Nd : YAG laser (λ = 1064 nm, 14 ns) was used to irradiate Al2O3 coatings, of different thickness (30–350 µm), deposited onto stainless steel substrates by atmospheric plasma spraying. The laser generated ultrasonic waves were in situ recorded at the epicentre using a laser heterodyne interferometer. The acoustic waveforms were correlated with the interaction between the pulsed laser radiation and the coated metal, taking into account the physical properties and the geometry of both the coating and the substrate, as well as the porosity of the coating. For the critical value of laser beam energy for which debonding just occurred, the stress field, owing to the combined thermal and acoustic effects of laser radiation, was calculated. The obtained valu...