Effects of Friction Layer Thickness on the Tribological Performance of Ni₃Al-Ag-MoO₃

In order to analyze the effects of friction layer thickness on the tribological performance of Ni₃Al matrix self-lubricating composites containing Ag and MoO₃ tabular crystals (Ni₃Al-Ag-MoO₃), the dry sliding tribological tests of Ni₃Al-Ag-MoO₃ against Si₃N₄ ball are undertaken under 4-16 N and 20-800 °C at 0.2 m/s. The results show that the friction layer thickness of Ni₃Al-Ag-MoO₃ is obviously affected by the applied loads and ambient temperatures. At 12 N-400 °C-0.2 m/s, Ni₃Al-Ag-MoO₃ exhibits excellent tribological performance, and the friction layer thickness obtained the maximum value of about 5 µm. Moreover, the simulation results, which based on the building of finite element models with different thickness of the friction layer, indicate that the decreased degree of the maximum equivalent stress in the substrate of Ni₃Al-Ag-MoO₃ with maximum thickness of friction layer is the larger one (about 39%), if compared to other thickness. It could avoid the generation of cracks and the spalling of subsurface materials during the dry sliding process, resulting in the excellent tribological performance. The results could be used to guide the selection of suitable working conditions and study the self-lubricating mechanisms of Ni₃Al-Ag-MoO₃ for having stable friction layer structure and excellent antifriction and antiwear performance.