Abstract

YPSZ-thermal barrier coatings are widely used in industries. Nevertheies there is secure interest in TBC's for higher temperature application. Ceria or miao-alloyed ceria shows the potential to be used at higher temperatures than YPSZ. Ceria and YPSZ-Ceria-multi-layer thermal barrier coatings were produced by plasma and high velocity oxygen flame (HVOF) spraying. Bond strength and thermal shock behaviour were tested. HVOF sprayed coatings had higher content of oxygen and higher density than plasma sprayed coatings. While plasma sprayed coatings showed microcracks originating in certain phases, HVOF sprayed coatings had cracks perpendicular to the surface across the whole layer thickness. In each case the bond strength was determined by the cohesion inside the ceria coating and not by the bondage between the layers. The thermal shock resistance of each type is limited by different properties of the occuring phases caused by impurities of the used powder. However an excellent bondage between YPSZ and ceria can be achieved. Pure ceria thermal barrier coatings are not suitable due to the high diffusion of oxygen and interaction with the MCr AIY bwid coat.

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