Erosion studies on duplex and graded ceramic overlay coatings

The solid-particle erosion resistance of ceramic thermal barrier coatings (TBCs) is of considerable economic and industrial significance. Of additional significance to the service performance of these coatings is the effort to minimize the differences in coefficients of thermal expansion between the metallic substrate and the overlay TBC. A new design strategy toward this effort is the introduction of functionally graded interlayers between the metallic and ceramic layers. This research examines the role of interlayer grading, microstructure, and thermal cycling on the solid-particle erosion behavior of partially stabilized zirconia and alumina coatings at ambient and elevated temperatures. The results point to beneficial effects of grading and processing on the elevated temperature erosion response of these deposits.