Microstructure, mechanical and high-temperature tribological properties of MoS2-Cr-Ag composite films

In the present work, MoS2-Cr-Ag composite films with various Ag content were synthesized by magnetron sputtering. The microstructure, mechanical and high-temperature tribological properties of as-prepared films were systematically investigated. The results indicated that MoS2-Cr-Ag composite films showed the preferred orientation of (002) crystal plane, which makes it have a dense structure. The maximum micro-hardness of MoS2-Cr-Ag composite films reached up to 309 HV, which was more than 4 times that of pure MoS2. The tribological properties of MoS2-Cr-Ag composite films at room temperature were evaluated. It was found that MoS2-Cr-Ag composite films presented significantly superior tribological properties than MoS2-Cr film at room temperature, which could be ascribed to the addition of Ag inhibits the oxidation of MoS2 and promotes the formation of a dense transfer layer on the surface of friction pair during the friction process. Furthermore, the tribological properties of MoS2-Cr-Ag composite films at 350 °C in air were also evaluated. It was also found that MoS2-Cr-Ag composite films presented superior tribological properties than MoS2-Cr film, which could be ascribed to the formation of Ag2Mo4O13 during the friction process at elevated temperature. In particular, MoS2-Cr-Ag composite film with 9.22 at. % Ag presented superior tribological properties at room temperature and at 350 °C high temperature. These results indicated that the appropriate amount of Cr and Ag co-doping can significantly improve the tribological properties of MoS2-based films at room temperature and 350 °C in air. It provided a design methodology to ameliorate the tribological properties of MoS2 film.