Phosphorus-free and sulfur-free organic molybdateester(ME) is more promising in modern engine oil applications due to its zero phosphorus and sulfur content, good friction-reducing properties, less corrosion and low price. In addition, it has been reported that there are good synergistic and friction-reducing properties between Zincdialkyldithiophosphate (ZDDP) and organomolybdenum.

Researchers at the Shanghai Jiaotong University, Lanzhou Institute of Chemical Physics and Luoyang Institute of Science and Technology have synthesized a non-active molybdate ester(ME) in a batch process and investigated its tribological properties.

The IR spectra of the ME and Organic amine.

The results indicate that ME possesses excellent anti-wear and friction-reducing properties, not load-carrying capacity. Both ME and ZDDP show excellent synergistic tribological behavior in 5CST. According to the XANES results, the tribochemical films generated from ME alone are mainly composed of MoO₃, and the tribochemical films generated from the oil blends containing ME and ZDDP consist mainly of MoS2, sulphate and polyphosphate.

The work has received support from the National Natural Science Foundation of China and the open projects of the Key State Lab of Solid Lubrication in Lanzhou of China. The findings have been published in Tribology International(Tribology International49 (2012) 90–95).