Abstract
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 °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 μm) with extremely narrow cracks (~0.15 μm). 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 μm 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.
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