Multilayer Mo2n-Ag/Sinx Films for Demanding Applications: Morphology, Structure and Temperature-Cycling Tribological Properties

Nowadays there is the need to avoid the excessive consumption of liquid lubricant phases, 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 phase. 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 weakened 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 attributed to the improvement on the tribological properties.