A Comparison of Sintering Behavior and Phase Transformation Characteristics Between Plasma Sprayed Commercial CSZ and Conventional YSZ Based TBCs

Abstract

Abstract Plasma-sprayed thermal barrier coating (TBC) systems are widely used in gas turbines blades in order to increase turbine entry temperature (TET) with better efficiency. Yttria stabilized zirconia (YSZ) has been usually chosen as the top thermal barrier coating material because of its low thermal conductivity, high thermal expansion coefficient and good corrosion resistance. However as a new candidate commercial TBC material, ceria stabilized zirconia (CSZ) currently looks to be promising. Ceria and ceria based ceramics show an outstanding potential for use at temperatures exceeding 1200 °C. CSZ coatings do not only have high temperature stability, good corrosion resistance and high fracture toughness but also lower thermal conductivity and higher thermal expansion coefficient than YSZ coatings. The sintering and phase transformation characteristics of both ceramic thermal barrier coatings under high temperature conditions are complex phenomena. In this paper, microstructural differences, sintering behaviours (1200 oC, 10h, 25h and 50h) and phase transformations of the plasma sprayed ceria stabilized zirconia (CSZ: ZrO2–2.5 wt.%Y2O3– 25 wt.%CeO2) and conventional yttria stabilized zirconia (YSZ; ZrO2–8 wt.%Y2O3) coatings and their powder materials have been investigated and compared using thermal analysis techniques, XRD and scanning electron microscope.