Fullerene-like MoS2 Nanoparticles and Their Tribological Behavior

Using a new quartz-made reactor, large amounts of fullerene-like (IF) MoS2 nanoparticles were synthesized by reacting MoO3 vapor with H2S in a reducing atmosphere. The nanoparticles were found to be of high crystalline order; with an average size of 70 nm and consist of more than 30 closed shells. Extensive tribological testing of the nanoparticles in two types of synthetic oils- poly-alpha olefins (PAO)- was carried out and compared to that of bulk (2H platelets) MoS2 and IF-WS2. These tests indicated that under high pressure and relatively low humidity, the IF-MoS2 exhibited a friction coefficient as low as 0.03 and the smallest wear rate of the measured systems. However, its performance was found to be lower in comparison to IF-WS2 after 2500 cycles, due probably to its inferior chemical stability. This study indicates that the tribological performance of the IF nanoparticles depends strongly on their crystalline order and size.