Multilayer Mo2N-Ag/SiNx films for demanding applications: Morphology, structure and temperature-cycling tribological properties.

[Display omitted] • A multilayered architecture of Mo 2 N-Ag and SiN x nanolayers in Mo 2 N-Ag/SiN x films. • Room temperature tribological properties were improved with increasing period thickness up to 64 nm. • Multilayered Mo 2 N-Ag/SiN x films avoided the excessive diffusion of Ag at elevated temperatures. • Inserting SiN x layers avoided the excessive diffusion of Ag at high temperature. • Multilayer films exhibited excellent temperature-cycling tribological properties. Nowadays there is the need to avoid the excessive consumption of liquid lubricant oils, as they are harmful to the environment and hard to disposal. Self-lubricant films have been seen as the sustainable solution to achieve a long-term lubrication under high temperature-cycling conditions. In this manuscript, multilayer Mo 2 N-Ag/SiN x films with a fixed modulation ratio (thickness of Mo 2 N-Ag to SiN x) of 3:1, with changing modulation period (Λ, thickness of Mo 2 N-Ag and SiN x) from 8 to 200 nm were produced to achieve an effective balance between the lubricious phase diffusion control and the adequate formation of the low friction tribo-layers. Results showed that a dual-phase of fcc-Mo 2 N and fcc-Ag co-existed in Mo 2 N-Ag layers, while the SiN x layer exhibited an amorphous character. Both room temperature (RT) lubricant and wear-resistance properties of the films were improved by increasing Λ from 8 to 64 nm, while a further increase of Λ degraded the wear-resistance properties. The multilayer film at Λ = 64 nm exhibited an excellent RT-500 °C temperature-cycling tribological properties. Mechanical properties and the synergistic effect of both modulation layers were the cause for the improvement of the tribological properties. [ABSTRACT FROM AUTHOR]