Plasma sprayed ZrO2 thick thermal barrier coatings.

ZrO2 thermal barrier coatings have been plasma sprayed onto steel substrates with a FeCrAlY bond layer. During spraying the conditions have been varied by cooling the back side of the substrate in ice-water or heating it on a hot plate, and simultaneously cooling the sprayed surface with air at various pressures. The residual strain distributions have been measured in the as-sprayed couples using the incremental blind-hole method. The measurements show that residual strains can be controlled through temperature manipulation, and the method can be used to determine the optimum spraying conditions. The microstructure has been observed in a transmission electron microscope, and the effect of microstructural features on the microstrains are briefly discussed.