Evaluation of 1,3-diketone as a novel friction modifier for lubricating oils

With the growing demand in both lubrication performance and environmental protection, it is eager to seek novel lubricant additives of good oil miscibility and high tribological efficiency but without harmful elements such as sulfur and phosphorus. As a recently developed material with superlubricity (μ < 0.01), 1,3-diketone EPND (1-(4-ethyl phenyl) nonane-1,3-dione) could modify the contacts of steel surfaces through the tribochemical reaction with iron and also exploit strong intermolecular forces to control the near surface fluid interactions. Owing to its oil-soluble nature, EPND also shows the potential functioning as an additive in lubricating oils. In this study, EPND was introduced into both pure base oils and fully-formulated oils to evaluate its performance as a novel friction modifier. The results suggest that with small influences on the viscosity and oxidation stability in the blended oil, EPND leads to an effective friction reduction in both boundary and mixed lubrication regimes. Moreover, the addition of EPND enhances the oil extreme pressure capacity as well. This work indicates that 1,3-diketone is a promising friction modifier even in the presence of some other commercial additives.