Tribological performance of Cu-modified large interlayer spacing 1 T/2H-MoS2 nanoparticles in soot-contaminated polyalphaolefin

A 1 T/2H-MoS 2 (THM) lubricant additive was synthesized via a solvothermal method to improve the lubrication of poly-alpha-olefin (PAO) and reduce the negative influence of diesel carbon soot (CS). The THM was then modified with Cu to further enhance the wear resistance. The average interlayer spacing of MoS 2 in THM and the Cu-modified THM (CTHM) was 0.99 nm, significantly larger than the 0.63 nm of 2H-MoS 2 nanoparticles. In PAO, CTHM demonstrated a 45 % improvement in friction reduction and a 77 % increase in wear resistance compared to 2H-MoS 2 . While the friction reduction of CTHM was similar to that of THM, CTHM exhibited 36 % superior wear resistance. In CS-contaminated PAO, CTHM outperformed 2H-MoS 2 with a 37 % reduction in friction and a 29 % enhancement in wear resistance. The Cu modification reduced the oxidation of CTHM and the conversion of 1 T-MoS 2 to 2H-MoS 2 in the tribofilm, contributing to improved wear resistance. The CS contamination negatively influenced the lubrication by accelerating MoS 2 oxidation, catalyzing the transition from 1 T-MoS 2 to 2H-MoS 2 , and inhibiting Cu incorporation into the tribofilm. Nonetheless, the effect of CS on CTHM and THM was less severe than on 2H-MoS 2 . This work provides an alternative method to alleviated the antagonism between MoS 2 and CS.