Silver-enhanced ZrN-MoSN composite films via magnetron sputtering: Insighting into the microstructure and optimizing self-lubricating properties

The multi-lubricant synergistic strategy is widely recognized as one of the most effective approaches for developing solid self-lubricant materials to replace conventional oil- or grease-based lubricant systems. This study employed RF magnetron sputtering to dope Ag into an optimized ZrN–MoSN system, with the aim of enhancing its tribological performance. Ag incorporation induced nanoscale structural heterogeneity within the film, resulting in a multiphase architecture comprising face-centered cubic (fcc) ZrN, fcc Ag, Mo–S–N species (hexagonal close-packed (hcp) MoS 2 , amorphous Mo(SN)ₓ, and MoS₂(N₂), and Ag–S-based compounds). Although Ag addition reduced the mechanical strength of the film, it markedly enhanced its self-lubricant capacity at both room temperature (RT) and elevated temperatures (500 °C). Tribological performance is driven by synergistic lubrication of multiple tribo-phases. At room temperature, the film contains MoS₂, MoO₃, and Ag₂Mo₂O₇, which transform at elevated temperatures into an oxide-dominated assemblage, primarily Ag₂MoO₄, revealing the temperature-dependent evolution of the tribo-phase. However, the trade-off between friction reduction and wear resistance persists, primarily owing to reduced hardness and the formation of mechanically fragile tribo-layers. • ZrN–MoSN–Ag composite films were deposited by RF magnetron sputtering. • Ag addition enhances 500°C self-lubricating despite reduced hardness. • High temperature lubrication mainly governed by tribochemical formation of Ag₂MoO₄.