STRUCTURE OF NiCrAlY COATINGS DEPOSITED ON SINGLE CRYSTAL ALLOY TURBINE BLADES BY LASER CLADDING

摘要

Single crystalline turbine blades are usually coated with materials such as MCrAlX-typernalloys (M=Fe, Co, Ni, X=Y, Hf, Ce, Zr) to improve their oxidation resistance. The protectivernaction of these coatings depends on the formation of an adherent and spallation resistant oxidernlayer that isolates the material from aggressive environments. Single crystalline coatingsrnprovide the possibility of the elimination of high diffusivity paths, such as grain boundaries,rnand so their utilization will significantly improve nickel alloys’ oxidation resistance. In the present work scanning electron microscopy and X-ray diffraction were used to show thatrnsingle and multilayer NiCrAlY coatings deposited by laser cladding on single crystallinernturbine blades grow epitaxially on the substrate and inherit the single crystalline nature andrnorientation of the base material.