The hot corrosion behavior of plasma sprayed zirconia coatings stabilized with yttria, ceria, and titania in sodium sulfate and vanadium oxide

Abstract

This paper compares the hot corrosion performance of yttria-stabilized zirconia (Zirconia-3-4Yttria, YSZ), ceria stabilized zirconia (Zirconia-24Ceria-2.5Yttria, CSZ), and titania stabilized zirconia (Zirconia-18Titania-10Yttria, TiSZ) coatings in the presence of molten mixture of sodium sulfate+vanadium oxide at 1050 °C. These coatings were prepared by air plasma spray (APS). Characterizations using X-ray diffraction (XRD) and scanning electron microscope (SEM) indicate that in the case of YSZ, the reaction between sodium vanadate (NaVO3) and yttrium oxide (Y2O3) produces yttrium vanadate (YVO4) and leads to the transformation of tetragonal zirconia to monoclinic zirconia. For the CSZ coatings, by the formation of cerium vanadate (CeVO4), the amount of yttrium vanadate formed on the CSZ coating is significantly reduced, thus the amount of monoclinic phase in the TBC coating is substantially reduced. For TiSZ coating, although some minor reactions happened and some titanium vanadate (TiVO4) ribbons formed on the surface of coating, tetragonal zirconia was stable after hot corrosion test and no monoclinic zirconia was formed. Comparing to YSZ and CSZ under a temperature of 1050 °C, TiSZ coating is found to be more stable, both thermally and chemically, and exhibits a better hot corrosion resistance.