Improved tribological and bearing vibration performance of calcium sulfonate complex grease dispersed with MoS2 and oxide nanoparticles

Molybdenum disulfide nanoparticles is an effective additive used to enhance the tribological properties of greases. However, there are four main mechanisms for improving the tribological properties of nanoparticles. Nano-MoS2 mainly plays the role of film formation, but it is difficult to achieve rolling, mending, and polishing effect. In this paper, based on addition of MoS2 nanoparticles, CuO, SiO2, and Al2O3 nanoparticles are further added to calcium sulfonate complex grease to achieve the other three effects, hoping to further improve the tribological performance of the grease. The tribological properties and the suppression effect on bearing vibration of the five greases were studied by four-ball friction experiment and bearing vibration experiment. The results show that a protective film consisting of MoS2 and MoO3 is formed on the worn surface. The addition of three oxide nanoparticles can further improve the properties of the calcium sulfonate complex grease containing MoS2 nanoparticles. Among them, calcium sulfonate complex grease with MoS2 and SiO2 nanoparticles performs the best, with 11.9% decrease in friction coefficient, 5.9% reduce in wear scar diameter, 27% decrease in the high frequency vibration of the bearing. The wettability test shows that the contact Angle of poly alpha-olefin 40 base oil on the thickening agent surface of calcium sulfonate complex grease containing MoS2 and SiO2 nanoparticles is the smallest, and it can be quickly added to the raceway.