Effect of graphene content on the tribological and corrosion behavior of high-speed-laser-clad high-entropy-alloy composite coatings

Abstract

To repair oil drill pipe joints that have failed owing to dry wear and tribocorrosion, graphene-reinforced CoCrFeMo0.5NiTi0.5 high-entropy alloy composite coatings (HEACCs) were developed through high-speed laser cladding. The HEACC containing 1.5 wt% graphene exhibited dry wear and tribocorrosion rates that were 59.18 % and 32.20 % of those observed in the high-entropy alloy coating, respectively. The HEACC exhibited a corrosion current density of 2.475 × 10−7 A/cm2. The HEACC containing 1.5 wt% graphene underwent progressive damage during dry wear owing to the combined effects of abrasive wear, which created furrows; adhesive wear, which led to flaking; and oxidative wear, which formed oxide layers. During tribocorrosion, chloride ions exacerbated surface damage caused by hard abrasives and asperities, intensifying corrosive–abrasive wear interactions.