Hot corrosion behavior of APS YSZ coatings treated by laser micro glazing (LMG) under molten salts (V2O5+Na2SO4)

In this study, yttria-stabilized zirconia (YSZ) coatings prepared by atmospheric plasma spraying (APS) were glazed by a nanosecond pulsed laser (laser micro glazing, LMG). The hot corrosion mechanism of as-sprayed, ground, and LMGed YSZ coatings was investigated at a temperature of 1100 oC in V2O5 and Na2SO4 molten salts for 20 h. The results show that a dense LMGed layer with narrow network of segmented microcracks (sub -micron level) was formed after the LMG process. Compared to the single-time LMG, pores can be effectively eliminated after six-times laser irradiation. The hot corrosion behavior of YSZ coatings exposed to molten V2O5 +Na2SO4 demonstrates that pores in the single-time LMGed layer seriously affect its hot corrosion resistance. After multiple LMG, the volume fraction of the m-ZrO2 decreases from 53% to 27% with the disappearance of pores. The quantity of the corrosion products YVO4 was greatly reduced and the depth of the damaged area diminished from 37.073 mu m to 20.918 mu m, which shows a significant improvement in molten salts corrosion resistance.