High-Temperature Friction and Wear of Ni Alloy-Based Composites Containing Ag/Ag-rGO/Ag-rGO-Ni

Abstract

In order to assess the potential of silver and reduced graphene oxide (rGO) in realizing self-lubrication over a wide range of temperatures, the tribological behavior of Ni alloy-based composites containing Ag/Ag-rGO/Ag-Ni-doped rGO (rGO-Ni) has been analyzed from room temperature (RT) to 800 °C at fixed load (5 N) and sliding speed (0.5 m/s). The results indicate that doping of rGO by Ni improved its wetting characteristics with the matrix, and the hybrid composite containing Ag-(rGO-Ni) achieved the same level of hardness as that of the base alloy. Both the coefficient of friction (CoF) and the wear rate decreased with the addition of either Ag or a combination of Ag and rGO/rGO-Ni from RT to 600 °C. Ni alloy-Ag-rGO-Ni composite showed the lowest CoF and wear rate from RT to 600 °C, which has been attributed to its higher hardness and the occurrence of a synergistic action between Ag and rGO-Ni in assisting each other’s lubrication capability. However, the combination of Ag-rGO and Ag-(rGO-Ni) did not reveal any assistive action beyond 600 °C, resulting in an increase in CoF at 800 °C, possibly due to the loss of lubricity of rGO. The relative dominance of the decrease in hardness and availability of lubricating oxides might have also played a vital role in controlling the friction and wear performance beyond 600 °C. © ASM International 2024.