Action mechanism of WS_2 nanoparticles with ZDDP additive in boundary lubrication regime

摘要

The effect in the tribological performance of WS_2 fullerene like nanoparticles in PAO base oil when adding a ZDDP additive was studied at 100°C in the boundary lubrication regime. The tribological properties of the dispersion surpass those obtained without one of the two additives. The friction modifier properties of the particles are improved in the presence of ZDDP, while the anti-wear properties of the ZDDP are increased when the particles are added to the dispersion. The composition of the formed tribofilm was investigated. Results show that a 50 to 60 nm tribofilm is formed on the steel surface composed by WS_2 mixed on the ZDDP chemical tribofilm. A WS_2 rich layer is observed at the top of the tribofilm. A correlation between the chemical composition of the tribofilm and the tribological properties of the "PAO + WS_2 + ZDDP" dispersion was made. Synergy between the two additives was proven.