Elastic Lubricious Effect of Solidlike Boundary Films in Oil-Starvation Lubrication

Herein, a boundary lubrication (BL) mechanism based on the carbon-based tribofilms formed via Ni(Cu)-catalytic dehydrogenation of hydrocarbon oils was queried by performing standard ball-on-disk tribotests on magnetron-sputtered WN, Ni, and W–N–Ni coatings in the oil-starvation condition. The experimental results indicate that both the bare GCr15 steel substrate and the sputtered W–N–Ni/MoN–Cu coatings exhibited comparable fine antiwear performance with friction coefficients below 0.09; however, no clues regarding the formation of the effectiveness of the graphite-like tribofilms on the contact surfaces were found, no matter whether the tested coatings were composited in amorphous or nanocrystallized structures. An understanding of the antiwear mechanism was achieved by conducting a nonequilibrium molecular dynamics (NEMD) simulation of the confined shearing process, taking 1-decene chains as a model of the poly-α-olefin 10 base oil. It was found that as the normal load increases from 0.14 to 9.2 GPa, the...