Evaluation under temperature cycling of the tribological properties of Ag-SiNx films for green tribological applications

Nowadays, one of the most important challenges in the tribology field is to avoid the excessive consumption of soft metals such as Ag at elevated temperatures through the re-design of the self-lubricant films, to achieve the long-term lubricant under the temperature-cycling environments, for widely used in real industrial applications. This paper took up this challenge to develop a novel green film, by composing nano-particles Ag into the amorphous SiNx matrix using magnetron sputtering system, for achieving the long-term lubricant under the room temperature (RT)-500 degrees C temperature-cycling conditions. Results showed that the film exhibited a dual-phase of face-centered cubic (fcc) Ag and amorphous SiNx. An excellent RT-500 degrees C wear-resistance performance was observed for the films with the Ag content of 1.3-9.4 at.%, whilst the film at 15.8 at.% Ag exhibited the best antifrictional performance (COF 0.3-0.5 for RT-500 degrees C conditions) at the cost of wear rate. The self-lubricant tribology behaviors under the RT-500 degrees C cycling conditions were mainly attributed by the synergism of: (1) mechanical properties, (2) excellent high-temperature chemical stability of SiNx matrix, and (3) the lubricant nature of Ag and its elevated temperature diffusion behaviors.