Hot corrosion behavior of EB-PVD YSZ coatings treated by nanosecond pulsed laser

In this study, yttria-stabilized zirconia (YSZ) fabricated by electron beam physical vapor deposition (EB-PVD) were treated by a nanosecond pulsed laser (here called laser micro glazing, LMG). The hot corrosion behavior of YSZ coatings was systematically investigated in the air at 1100 degrees C with a mixture of 55 % V2O5 and 45 % Na2SO4 for 20 h. The results show that the LMG process can produce a dense and smooth LMGed layer (-0.25 mu m) with extremely narrow cracks (-0.15 mu m). The phase composition (tetragonal ZrO2) of LMGed 8YSZ does not change at the rapid cooling rate. Nevertheless, it shows a preferred orientation from (200) to (101). Due to the presence of the LMGed layer, the penetration of molten salt is limited during the hot corrosion test. A sintered layer-10 mu m is formed under the top region of LMGed coatings and becomes a second barrier layer. The volume fraction of m-ZrO2 in LMGed coatings decreases from 65.43 % to 35.64 %, and the t-ZrO2 is closely spaced. The YVO4 is also diminished on the surface and between inter columnar gaps, which demonstrates the better hot corrosion resistance.

Automated summary

YSZ coatings treated by laser micro glazing showed improved corrosion resistance and the formation of a sintered layer as a second barrier.