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% BaF2/CaF2) 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 x 10(-5)-15.2 x 10(-5) mm(3).N-1.m(-1)at a wide temperature range from 25 to 800 degrees 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, BaF2/CaF2, Ag2MoO4 and BaMoO4.