Tribological Behavior of Ni Alloy-Ag/rGO Composites against Si3N4 at Extreme Temperatures

Abstract

The present study aims to investigate the lubrication potential of the combination of Nickel-doped reduced graphene oxide (rGO-Ni; 0.5, 1.0, 1.5 and 2.0 wt pct) and Ag (10 wt pct) in Spark Plasma Sintered (SPS) Ni-alloy based composites by carrying out tests at 5N load and 0.5 m/s from room temperature (RT) to 800 °C for realizing low friction and low wear which is hitherto unexplored. The doping of rGO with Nickel has been done to improve its wettability with the matrix. Field emission scanning electron microscopy, 3D optical profilometry and X-ray diffraction analysis have been carried out on the worn surfaces to reveal the operating mechanisms of wear. The results indicate that the coefficient of friction (CoF) and wear rate decreased with increasing amount of rGO in the composites and the one having 2.0 wt pct rGO-Ni exhibited the lowest CoF (~ 0.42–0.47) and wear rate (~ 2.84–73.49 × 10−5 mm3/Nm) from RT to 600 °C due to cooperative synergy between the solid lubricants. However, both CoF and wear rate increased from 600 to 800 °C for the composites containing Ag and rGO-Ni due to the probable loss of assistive action between rGO and other lubricating species (silver molybdates or oxides). © The Minerals, Metals & Materials Society and ASM International 2024.