Nanodiamond-based nanolubricants for motor oils

Over the last few years, interest in applications of nanoparticles as lubricant additives has steadily grown due to the demonstrated reduction in friction and wear of nanoparticle-containing lubricant formulations (so-called nanolubricants). Particularly, studies of motor oils containing a “green” all-carbon additive, detonation nanodiamond (DND) particles, revealed their positive impact on the performance of lubricant compositions and fuel economy in engine tests. In the current review we discuss critical issues toward successful implementation of DND in nanolubricants: role of DND structural characteristics, stability of colloids of DND in oils, DND compatibility and synergism with other additives in commercial oils, mechanisms of DND impact on the properties of lubricants. Owing to the abrasive nature of diamond, DND-based nanolubricants must be carefully engineered in order to avoid increased wear of the friction surfaces and get full benefit from significantly reduced friction of well-polished surfaces.