Comparative Study on the Effect of Different Lubricating Oil Additives on the Tribological Properties of Bearing Steel

The purpose of this article is to study the antifriction and anti-wear effect of GCr15 bearing steel under paraffin base oil and the base oil with two additives of T405 sulfurized olefin and nano-MoS2 and compare the synergistic lubrication effect of two different additives (MoS2 and T405) in paraffin base oil. The tribological properties of GCr15 bearing steel under different lubrication conditions were tested on a ball-on-disk tribometer. The three-dimensional profile of disk's worn surfaces and the scanning electron microscope (SEM) micrographs of corresponding steel balls were analyzed at the same time. The wettability of lubricating oils on the surface of friction pairs and the dispersibility of MoS2 in base oil were characterized. Furthermore, the Energy Dispersive X-ray Analysis (EDAX) of the disk's worn surfaces under the nano-MoS2 base oil were measured by the Field Emission Environmental Scanning Electron Microscope to observe the variation of chemical elements on the worn surface of the disk after tests. The results show that these additives have a good synergistic lubrication effect with the base oil in terms of friction coefficient, wear volume, and surface wettability, and nano-MoS2 is better than 1405 as the additive in the base oil. Moreover, active elements such as Mo and S were observed on the worn surface of the friction pair, indicating that the MoS2 additive can form a deposited film on the contact region to achieve antifriction and wear resistance effect.