Influence of the micro structure of plasma deposited MCrAlY coatings on their tribological behaviour

Abstract

MCrAlY coatings (CoNiCrAlY) were thermal sprayed under various atmospheres (air, argon, vacuum) on a nickel-based superalloy (Hastelloy X). Their microstructures (porosity, presence of oxides and phase composition) and mechanical properties (hardness and Young modulus) were characterized. The friction behaviour of these coatings sliding against a low-pressure plasma sprayed NiCoCrAlYTa coating was evaluated under fretting conditions. The study focused mainly on the different degradation mechanisms that may occur. Depending on the coating microstructure, two kinds of damage were observed: particle detachment and microstructural transformation (tribologically transformed structure). Adhesion and oxidation wear were also studied. © 1998 Elsevier Science S.A.