Thermal cycle resistance of yttria stabilized zirconia coatings prepared by MO-CVD

Yttria stabilized zirconia (YSZ) coatings containing 0 to 9.5 mol% Y2O3 were prepared on Hastelloy (.) XR alloys by metal-organic chemical vapor deposition (MO-CVD) and the effect of Y2O3 content on thermal cyclic resistance was investigated in the temperature intervals from 600 to 1273 K and from 600 to 1373 K in air. In the 600-1273 K interval. delamination after 1200 cycles had not occurred for any of the Y2O3 contents of YSZ coatings. In the 600-1373 K interval. the YSZ coatings containing 0.05 and 9.5 mol% Y2O3 suffered partial delamination after 1200 cycles, while no delamination was observed for the YSZ coatings containing, 4 mol% Y2O3. During the thermal cycles, thermally grown oxide (TGO) layers consisting of inner Cr2O3 and outer (Ni.Mn.Fe)(Fe.Cr)(2)O-4 spinel were formed at the YSZ coating/Hastelloy-XR substrate alloy interface, The delamination of YSZ coatings occurred at the alloy side near the TGO layer/Hastelloy-XR alloy interface.