Insight into the Influence of Ag Contents on Microstructure, Mechanical and Tribological Performance of MoN-Ag Coatings

Abstract

In this document, RF magnetron sputtering to generate a set of composite coatings comprising MoN and Ag, exhibiting diverse concentrations of silver (Ag). Comprehensive investigations were conducted to scrutinize the coatings, encompassing an examination of their microstructure, mechanical attributes, and tribological performance. This multi-faceted analysis leveraged state-of-the-art techniques, such as XRD, SEM, HRTEM, EDS, etc. Our research findings suggest that the MoN-Ag coatings revealed a composite composition, comprising structures of fcc-Mo2N and fcc-Ag. As the Ag content was elevated, the coating’s hardness initially exhibited a gradual augmentation before subsequently declining after reaching its zenith, with the highest hardness recorded at 26.7 GPa. At room temperature, the MoN-Ag coating displayed a distinctive tribological behavior, where the average friction coefficient experienced an initial rapid reduction followed by a gradual increment. Notably, the coefficient reached its nadir at 0.38 with an Ag content of 3.90 at.%. Moreover, the wear rate of the coatings exhibited a similar trend, registering a slight decline followed by an increase as the Ag content was augmented, with the lowest recorded value being 1.63×10−8 mm3N−1mm−1 at an Ag content of 1.61 at.%. In the case of MoN-Ag coatings, the average friction coefficient initially exhibited an increase, followed by a swift decline as the temperature rose from ambient to higher levels. This coefficient reached its lowest value, 0.29, at 600 °C. In contrast, the wear rate showed a steady escalation in line with the temperature increase, peaking at a maximum of 2.77×10−7 mm 3 N−1mm−1 at 600 °C.