Tribological properties of plasma-sprayed nickel alloy matrix self-lubricating coating at elevated temperatures

A nickel alloy matrix high-temperature self-lubricating coating (77.5 wt% (Ni–Cr–Mo–Al)–12.5 wt% Ag–10 wt% BaF 2 /CaF 2 ) was prepared by plasma spraying technique. Results show that the Vickers microhardness of coating is (2.9 ± 0.5) GPa, and the average bonding strength is about (35.6 ± 0.5) MPa. The coating rubbing against Inconel 718 superalloy pin exhibits superior tribological performance with coefficient of friction (COF) of below 0.25 and wear rate of 8.2 × 10 –5 –15.2 × 10 –5 mm 3 ·N −1 ·m −1 at a wide temperature range from 25 to 800 °C, and the COF and the wear rate are slightly reduced with temperature increasing. The low COF and wear rate were attributed to the synergistic effects of Ag, BaF 2 /CaF 2 , Ag 2 MoO 4 and BaMoO 4 . Graphic abstract