Microstructural Evolution and Tribological Responses of Heat-Treated AlFeCoNiCr–Cr3C2 Coating

Abstract

Metal–carbide coatings with high hardness, high wear resistance and good thermal stability are widely used for surface protection of key equipment in high-temperature environments. However, the metal binder is susceptible to oxidized spalling and wear failure during long-term operation. This leads to severe limitations in the service life and stability of the coatings. In this study, an AlFeCoNiCr–Cr₃C₂ coating with high-entropy alloy as metal binder was fabricated by supersonic atmospheric plasma spraying. The effect of heat treatment on the microstructure, mechanical properties and tribological responses of the coating was studied comparatively. The results suggested that heat treatment at 600 °C resulted in the formation of nano-carbides (Cr₂₃C₆), a disordered BCC and FCC phases. The evolution of the phase structure synergistically increased hardness and toughness, thereby reducing wear rate and improving the high-temperature wear resistance. The primary wear mechanisms were abrasive and oxidation wear. Wear debris consisted mainly of phases such as NiCr₂O₄, Al₂O₃, NiO and Fe₂O₃.

Graphical Abstract