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Molybdenum disulfide (MoS) nanosheets are a promising lubricant additive for enhanced engine efficiency in cars. However, high-cost production methods and poor dispersion have limited their application in industry. In this study, the ball milling process is demonstrated as a low-cost and high-efficient method for fabrication of oil-dispersible MoS nanosheet, and the ball milling parameters are optimized. Moreover, the lubrication effectiveness of ball-milled MoS nanosheet was also evaluated. Results indicated that well-dispersed MoS nanosheets with a size of 250 nm can be manufactured with optimized surfactants of zinc dialkyldithiphosphates (ZDDP) and polyisobutylene succinimide (PIBS) after being ball milled for 36 h. Tribological results revealed that a friction coefficient of white oil with 0.25% MoS nanosheets reached 0.075, much lower than that of lubricant without nanosheets (0.16). The wear scar radius of 0.015% MoS nanosheets was similar with that of Hertz contact, and the wear scar radius reduction reached 20% compared with that of 1% ZDDP. In addition, EDS and XPS results indicated the formation of a MoS and FeS tribofilm on the wear surface. [ABSTRACT FROM AUTHOR]

The compatibility and effectiveness of nanoparticles with the existing additives in formulated oil are still unclear. In the present study, some lubricant additives were selected to modify nanoparticles to obtain friendly capped nano-MoS2. Various polyisobutyleneamine succinimide (PIBS) concentrations were applied to investigate the lubrication effectiveness of capped nano-MoS2. The results showed that the reduction in COF and wear volume of friendly capped nanoparticles without PIBS reached about 35% and 75% in comparison with those of the base oil respectively. However, the average coefficient of friction and wear volume loss of nano oil increased with PIBS concentration in the range of 0.05%-1%. By scanning electron microscope, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analysis, it is identified that (i) MoS2 tribofilm was formed on the wear track for the oil with nano-MoS2 and (ii) wear scar was smooth for nano-MoS2 with low PIBS concentration and without PIBS, while it showed plowing wear when containing high PIBS concentration. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The purpose of this work was to expand the applications of molybdenum disulfide (MoS 2 ) nanosheet additives by investigating their effectiveness and advantages for lubricating line contacts between bearing steel and medium carbon steel surfaces. The friction and wear effects of MoS 2 nanosheet additives were investigated using block-on-ring tests, and compared with those from zinc dialkyldithiphosphates (ZDDP). Both additives were combined with ISO VG 32 white oil as base fluid. Results suggest 0.25 wt% MoS 2 nanosheets exhibited similar friction coefficient, oil temperature and wear scar width with those of ZDDP at low loads; while the reductions of friction coefficient and wear scar width were 28.6% and 34.3%, respectively, compared to the behavior of ZDDP at high load (459 N). Furthermore, the wear scar widths of the ZDDP containing oil significantly increased in 2 h tests, while they remained constant with a smaller size for 0.25 wt% additives of MoS 2 nanosheets at a load of 326 N. Scanning electron microscope observations showed some pits on the wear scar lubricated with ZDDP, compared with spalls for 0.06 wt% MoS 2 nanosheets. The wear scar was smooth and had a patched film for tests using 0.25 wt% MoS 2 nanosheets. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analysis revealed that the patched surface film was composed of MoS 2 and phosphate, and that film reduced friction coefficient and wear. The results highlight how high concentration MoS 2 nanosheets exhibit significant advantages over ZDDP in reducing friction and wear in high load in line contact. [ABSTRACT FROM AUTHOR]