Tribological Performance of Gradient Ag-Multilayer Graphene/TC4 Alloy Self-Lubricating Composites Prepared By Laser Additive Manufacturing

Based on a functionally graded material (FGM) design concept, the laminated-graded Ag-multilayer graphene/TC4 alloy self-lubricating composites (GTMAC) were prepared to overcome the poor friction and wear behaviors of TC4 alloy and expand engineering applications where friction is involved. Tribological experiments on GTMAC were carried out under different temperatures and loads in contrast with TC4 alloy (TC4) and homogeneous Ag-multilayer graphene/TC4 alloy self-lubricating composites (TMAC). The results show that GTMAC presents better friction and wear behaviors compared with TC4 and TMAC over a broad range of temperatures and loads. This is because of the synergistic effect of Ag and multilayer graphene, which are crushed and spread out in the sliding process, resulting in the formation of a lubricating film on the worn surface. Additionally, the equivalent stress distributions on the friction surfaces of TMAC and GTMAC are investigated using a finite-element method. The simulation results indicate that the GTMAC sample model with a smaller equivalent stress can avoid the occurrence of cracks and peeling of the surface material, so the the lubricating film is formed easily and remains for a longer working time.