Yb 2 O 3 -Doped YSZ coatings: Phase stability and thermal performance

Ytterbium(III) oxide (Yb 2 O 3 )-doped yttria-stabilized zirconia (YbYSZ) thermal barrier coatings were prepared via EB-PVD. Elemental analysis showed that the contents of Yb, Y, and O decreased from ingot to coatings and the total amount of stabilizer in 4.5Yb4YSZ coating was higher than that in 6.5Yb2YSZ coating. The total content of tetragonal and tetragonal-prime phases in as-deposited 6.5Yb2YSZ and 4.5Yb4YSZ coatings and coatings after 6000 thermal cycles at 1150°C were 95, 97 mol.%, and 61, 72 mol.%, respectively. The failure of coatings was attributed to the generation of vertical and horizontal cracks in ceramic layer caused by thermally-grown oxide (TGO) fluctuation and ceramic sintering, followed by delamination of the coatings. Finally, 4.5Yb4YSZ coatings exhibited a better sintering resistance that delayed the generation of Cr 2 O 3 and NiO and the growth of TGO. After 4000 thermal cycles, the thickness of TGO on 6.5Yb2YSZ and 4.5Yb4YSZ coatings was 10–14 and 8–10 μm, respectively.