Laser Shock Adhesion Test (LASAT) of Electron Beam Physical Vapor Deposited Thermal Barrier Coatings (EB-PVD TBCs)

Abstract

Abstract. Damage prediction, adhesion strength and remaining lifetime of TBC are highly important data for understanding and preventing TBC spallation on blades. LAser Shock Adhesion Test (LASAT) is a powerful method to measure adhesion of coating due to its rapidity, simplicity and capabilities to distinguish different strength levels and the easy damage observation in case of TBCs. A new protocol of LASAT has been introduced in order to measure the adhesion level of the ceramic coating from the exploitation of the two-dimensional effects that promotes a shock wave pressure-dependent size of the damage. Finite element modeling, taking into account the TBCs dimensions, showed the edges effect on interfacial stress applied by laser shock.

Laser surface patterning to enhance adhesion of plasma sprayed coatings

“…Those thicknesses are adapted to have maximum energy near the interface (thickness linked to the sound speed in the coating) [34]. Indeed, the characteristics of the shock wave (pressure level, duration, shape…) are directly linked to the pulse and confinement parameters used during the LASAT.…”

“…For a given coated system and laser duration, a laser intensity debonding threshold is then determined by increasing step by step the laser power density (in GW/cm 2 ). The adhesion strength value (GPa) is then identified with numerical simulation of shock wave propagation inside the material reproducing experimental free surface velocity data [34].…”

Laser-Assisted Cold Spray (LACS)

“…LASAT was applied successfully for the adhesion characterization of coatings which have been produced by EB-PVD (Fabre et al, 2011).…”

Nd YAG Laser

“…Recently, LASAT was used also for other type of coatings and not only for thermal sprayed coatings. LASAT was applied successfully for the adhesion characterization of coatings which have been produced by EB-PVD (Fabre et al, 2011).…”