Enhancement of the tribological behavior of self-lubricating nanocomposite Mo2N/Cu films by adding the amorphous SiNx

Addition of soft Cu into hard Mo2N matrix could improve its wide-temperature self-lubricating property, but the consumption of the lubricating phase during the lubrication process sacrificed its wear-resistance property. In this paper, amorphous SiNx was added to encapsulate Mo2N and Cu phases using magnetron sputtering to improve the wear-resistance property. Results showed that Mo2N/Cu/SiNx films were mainly composed of face-centered cubic (fcc) solid solution of (Mo1-xSix)(2)N, fcc-Cu and amorphous (a) SiNx phases. Both dislocation increments in crystallites and micro-crack propagations in the interface were limited by the a-SiNx, and it resulted in the enhancement on the hardness from similar to 17 GPa for the film at 0 at.% silicon to similar to 30 GPa for the film at 3.3-5.7 at.% silicon. Addition of silicon below 5.7 at.% could improve the wear-resistance property at room temperature (RT). The film at 5.7 at.% silicon also exhibited an excellent wear resistance property after the RT500 degrees C temperature cycling wear experiment. The a-SiNx phase, which encapsulated both (Mo1-xSix)(2)N and Cu phases, attributed to the improvement on both the RT wear-resistance property and RT-500 degrees C temperature cycling capability.