Study on application of CeO_2 and CaCO_3 nanoparticles in lubricating oils

The ceria （CeO2） nanoparticles and calcium carbonate （CaCO3） nanoparticles were chosen as additives of anti-wear and extreme pressure for lubricating oils, and the morphology and sizes of nanoparticles were examined using Transmission Electron Microscope （TEM）. The tribological performance of lubricating oils containing combined nanoparticles were determined by four-ball friction and wear tester, and the chemical composition of steel ball with worn surface were analyzed by X-ray Photoelectron Spectrurn（XPS）. The results showed that the lubricating oils containing combined nanoparticles had good anti-wear and friction reducing effects, and the tribological properties were optimal when WCeO2＋CaCO3=0.6%, WCeO2：WCaCO3=1：1. The extreme pressure value increased by 40.25%, the wear spot diameter reduced by 33.5%, and friction coefficient reduced by 32% compared with 40CD oil. The coordinated action of big and small particles made anti-wear and friction reducing effective. Tribological chemical reactions resulting from the friction surface formed metal calcium, metal cerium and oxides film, and they could fill up the concave surface and protect the worn surface.

Study on Tribology Performance of Different Lubricant Additives under Atmospheric Pressure and High Vacuum Conditions

By using PAO-10 as the base oil, the tribological behavior of 11 additives under high vacuum condition was evaluated. By adopting some surface analytical instruments, such as scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS), the tribological mechanisms of these additives were studied. In air, O_2 can react with metal to form metal oxide that can protect the surfaces of rubbing pair during the tribological tests. According to the theory of the competitive adsorption, the function of some active elements is weakened. In a vacuum environment, the additives contributed more to the lubrication performance. The sulfur-containing additives could react with Fe to produce Fe Sx and "M—C" bonds("M" represents metal). They both had contributions to the lubrication. As for the phosphorus-containing additives, they only generated the phosphates during the tests. When the sulfur and phosphorus-containing additives were applied, the generated phosphates and Fe Sx had the primary contribution to the lubrication performance during the tests.

Synthesis and evaluation of a protic ionic liquid as a multifunctional lubricant additive

An oil soluble multifunctional protic ionic liquid(IL)was synthesized and its tribological and antioxidant properties in poly alpha olefin(PA04)were investigated.The tribological results demonstrated that the IL significantly reduced friction and wear of PA04.The PA04 blend with IL resulted in an induced oxidation time of 555 min which is 8.2 and 3.5 times higher than that of pure PA04 and PA04 with zinc dialkyl dithiophosphate(ZDDP)for the rotating pressure vessel oxidation test.It is likely that free nonylated diphenylamine acted as a radical scavenger to enhance antioxidant performance,while free bis(2-ethylhexyl)phosphate was more prone to adsorb and react with the metal surface to form a phosphorus-rich tribofilm in order to protect the rubbing surface.