Nanocomposite Mo-Ag-N lubricating, wear resistant and hard coatings fabricated by magnetron sputtering

•Mo-Ag-N nanocomposite coatings were prepared by d.c. Magnetron sputtering technique.•The effect of annealing temperature and Ag content on the hardness and tribological performance of Mo-Ag-N coatings was investigated.•Mo-11.6 at.% Ag-N coating has friction coefficient 0.24 and wear rate 5 × 10−6 mm3/N·m. Mo-Ag-N coatings were prepared by d.c. magnetron sputtering technique from a Mo target with embedded Ag pellets, followed by vacuum annealing at 425, 500, and 600 °C, respectively, for 1 h. SEM, EDS, XRD, nanoindenter, and micro–macro tribometer were used to investigate the influence of Ag content and annealing temperature on their microstructure, surface morphology and mechanical properties. Results demonstrated that as-deposited Mo-Ag-N coatings consisted of fcc γ-Mo2N phase and fcc Ag phase where Ag uniformly distributed into Mo-N matrix. The hardness of Mo-Ag-N coatings initially increased and then decreased with Ag content, reaching the maximum hardness of 32 GPa at 4 at.% Ag, whereas friction coefficient decreased monotonously with Ag content increasing. With the increase of annealing temperature hardness, friction coefficient, and wear resistance were decreased due to the accumulation of a large amount of Ag agglomerates onto surface resulted from high temperature intriguing phase segregation and diffusion.