Microstructure and Tribological Properties of Plasma-Sprayed CoCrFeNi-based High-Entropy Alloy Coatings Under Dry and Oil-Lubricated Sliding Conditions

摘要

The CoCrFeNi-based high-entropy alloy coatings were prepared by atmospheric plasma spraying. The microstructure, phase, microhardness and corrosion resistance of the coatings were characterized. The tribological properties of the coatings sliding against GCr15 balls under dry and oil-lubricated sliding conditions were investigated. The results show that the phase composition of the CoCrFeNiAl coating is mainly BCC phase, accompanied by a small amount of FCC phase and AlCrO3 oxide phase. The oxide phase is mostly distributed at the splat interfaces, which leads to a low cohesive strength and high wear rate under both dry and oil-lubricated sliding conditions. The CoCrFeNiMn coating is composed of FCC phase and relatively large amount of MnCr2O4 oxide phase. High oxides content and good plastic deformation ability contribute to the formation of tribolayer on the worn surface, which promotes excellent wear resistance under both conditions. The CoCrFeNiMo0.5 coating consists of mostly FCC phase and a bit of aggregated Cr2FeO4 oxide phase. Its dominant wear mechanism is abrasive wear.