X-ray diffraction and electron microscope studies of yttria stabilzed zirconia (YSZ) ceramic coatings exposed to vanadia.

Abstract

The U.S. Navy sometimes has the requirement to use low cost fuels containing significant amounts of vanadium and sulfur in gas turbine engines. Unfortunately the yttria stabilized zirconia (YSZ) which is used as a thermal barrier coating on gas turbine blades can be severely attacked by vanadia. Powders of YSZ containing 8-mol% Y2 3 and pure zirconia containing various amounts of V2Os were annealed at 900°C. These were then examined by X-ray diffraction and electron microscopy, as well as single crystals of pure Zr02 and YSZ ( 20%wt Y2 3 ) exposed to V2 5 melts, to study how the vanadium degrades the YSZ by reacting with the stabilizer to form YV04 and how the vanadia transforms the cubic and tetragonal YSZ crystal structures to monoclinic which degrades rapidly as a gas turbine blade coating.