Study Of Tribological Performances Of MoS₂ Nanoparticles

It is reported that the preparation and tribological performances of nanosize molybdenum disulfide (MoS2) particles. By the mixing of sodium sulfide and sodium molybdate within a suitable pH range, molybdenum trisulfide particles were obtained as precipitation substance. Then the molybdenum disulfide nanoparticles which size was in the range of 20-30 nm were prepared by the desulfuration of molybdenum trisulfide if taking hydrogen as a protection atmosphere at some temperature. The MoS2 nanoparticles were then characterized by X-ray diffraction and transmission electron microscope.The MoS2 nanoparticles and commercial common MoS2 particles (c.a. 1.5μm in diameter) were dispersed in N46 engine oil with different concentrations using ultrasonic respectively in order to study their tribological properties. The tribological experiments were carried out by MQ-800 four-ball tribometer and MM-200 ring-on-block tribometer, in which extreme pressure properties, wear scan diameter, friction coefficient and wear volume loss were measured. The results showed that oil containing MoS2 nanoparticles had a better wear resistance, friction-reducing and extreme pressure than the oil containing common MoS2. In order to discuss the friction and wear mechanisms of MoS2 nanoparticles, it was analyzed that the chemical status of elements existed on the rubbed surface by X-ray photoelectron spectroscope, and it was observed that the surface topography of wear zone by scanning electron microscope. It was suggested that the difference in the tribological performance between MoS2 nanoparticles and common MoS2 particles was attributed to the surface and interfacial size-effect of nanoparticles and the formation of molybdenum trioxide thin film on the rubbed surface.