Enhancement of the mechanical and tribological properties of self-lubricant Mo2N-Ag composite film by adding amorphous SiNx

In this paper, the Si was introduced into the Mo2N-Ag matrix to synthesize the Mo2N-Ag-SiNx composite films using the magnetron co-puttering technology, designed to provide low-friction and long-term green tribological solutions for the demanding applications used at elevated temperatures. The results showed that the fcc-Mo2N, fcc-Ag, and amorphous SiNx were the main phases in the composite films. Adding Si of above 1.3 at.% could increase the hardness as well as the elastic modulus to -21 and -245 GPa. The average friction coefficient (COF) at room temperature (RT) exhibited a slight effect from the Si content, and its value was kept at 0.54-0.60, regardless of Si content. However the RT wear rate was significantly enhanced by adding Si of 1.3 at.%, due to the enhancement on the mechanical properties. At 600 degrees C, the COF decreased from 0.24 at 0 at.% Si to 0.19 at 5.0 at.%, but further increasing the Si content led to an increase in COF. The wear resistance was significantly enhanced by adding Si. It was mainly influenced by the lubricant transfer layers.