LASER ADHESION TEST: A TOOL FOR BOND STRENGTH TEST USING HIGH PRESSURE SHOCK INDUCED BY LASER

摘要

This paper deals with the LASAT technique (LASerAdhesion Test) developed in order to become a nonintrusivebond strength test for coatings. Thistechnique consists in irradiating target(substrate+coating) with a laser in GW/cm2 range togenerate high-pressure shock wave (GPa), which thepropagation can lead to the interface debonding and/ormaterial spallation. Experimentally, a Doppler laserinterferometer (Velocimetry Interferometer System forAny Reflector) measures the velocity time history atthe rear surface. This velocity profile allows debondingand spallation detection. This paper presents our lastresults concerning this technique. Applied to Ni coldspray coating on Cu substrate, physical mechanisms ofshock wave propagation are studied in using 1DSHYLAC (Simulation HYdrodynamique Lagrangiennedes Chocs) code. Calculations reproduce velocityprofile even for debonding with typical criteria forspallation. Results show also the brittleness of thecoatings compared to the interface.