High-temperature tribological properties of a novel AlFeCoNiCr - Cr 3 C 2 cermet coatings

Microstructural instability of NiCr-Cr 3 C 2 coating greatly limits its high-temperature tribological applications. In this work, we present a design concept for NiCr alloys based on an enthalpy-guided approach. A novel AlFeCoNiCr-Cr 3 C 2 coating was fabricated using a supersonic plasma spraying followed by annealing. The hightemperature tribological results suggested that, due to the precipitation strengthening of Cr 23 C 6 nano-grains in the interfacial transitions and the high plasticity of the disordered BCC (A2) and FCC (A1) phases in the AlFeCoNiCr alloy, the wear rate of the coating after annealing at 600 degrees C decreased by 47.6 % compared to the NiCr-Cr 3 C 2 coating. The high density of mesoscopic defects further contributed to the strengthening and plasticity of the coating. After annealing at 900 degrees C, a net-shaped agglomeration of Cr 23 C 6 and A2 phases accelerated oxidation diffusion and abrasive wear, leading to an increase of wear rate of coating. The produced wear debris mainly came from NiCr 2 O 4 , Cr 2 O 3 , NiO, Al 2 O 3 and Fe 2 O 3 , where the NiCr 2 O 4 was the product from the reaction between the Cr 2 O 3 and NiO phases.