Femtosecond laser polishing yttria-stabilized zirconia coatings for improving molten salts corrosion resistance

Abstract

In this study, we present a novel method of polishing thermal barrier coatings' surface using high-frequency femtosecond laser. Compared to the conventional mechanical micro-grinding, light trapping due to multiple reflection from porous-structure, which enhances its coupling into coating, resulted in desired effect of healing of the voids in performing a layer-by-layer laser ablation. Herein, the corrosion resistances of these coatings subjected to Na2SO4+V2O5 at 1000 °C was investigated. Three observed transport behaviors: (i) molten salts infiltration, (ii) Y-leaching, and (iii) V-in-diffusion, are discussed to illustrate corrosion mechanisms. Laser-polished coatings with smooth surface and healed voids show superior molten salts resistance and significantly alleviate leaching or in-diffusion of elements.