Comparison of hot corrosion behaviors of plasma-sprayed nanostructured and conventional YSZ thermal barrier coatings exposure to molten vanadium pentoxide and sodium sulfate

The purpose of the current study was evaluation and comparison of hot corrosion behaviors of plasma-sprayed conventional and nanostructured yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs). Hot corrosion studies were performed on the surface of coatings in the presence of a molten mixture of V₂O₅+Na₂SO₄ at 1000°C for 30h. Results indicated that the hot corrosion mechanisms of conventional and nanostructured YSZ coatings were similar. The reaction between corrosive salt and Y₂O₃ produced YVO₄, leaching Y₂O₃ from YSZ and causing the detrimental phase transformation of zirconia from tetragonal to monoclinic. The nanostructured coating, as compared to its conventional counterpart, in spite of a further reaction with the corrosive salt, showed a higher degradation resistance during the hot corrosion test due to increased compliance capabilities resulting from the presence of an extra source of porosity associated with the nano-zones.