Tribological performance of ultrathin MoS2 nanosheets in formulated engine oil and possible friction mechanism at elevated temperatures.

MoS 2 nanoparticles have been extensively applied as lubricating additives enhancing tribological behavior of base oils over the past decades. But how MoS 2 nanoparticles specially behave in formulated engine oil is still poorly understood, and even some contradictory conclusions have been obtained. Herein, ultrathin MoS 2 nanosheets were synthesized through a chemical method and their friction-reducing and antiwear capabilities in formulated engine oil was investigated. In addition, the tribofilm formation, interface structure and friction mechanism were studied in terms of the surface characterization and chemical analysis. The research contributed to comprehending the lubrication mechanism of MoS 2 nanoparticles within formulated engine oil. • The ultrathin shape of MoS 2 nanosheets with 1–4 layer were fabricated. • Ultrathin MoS 2 nanosheets showed positive tribological response in formulated engine oil. • Ultrathin MoS 2 nanosheets restrained the oxidation of substrate at high temperature. • A tribofilm with embedment of MoS 2 nanosheets was formed to protect rubbing surfaces. [ABSTRACT FROM AUTHOR]