Improving the tribological behavior of internal combustion engines via the addition of nanoparticles to engine oils

The friction between two sliding surfaces is probably one of the oldest problems in mechanics. Frictional losses in any I.C. engine vary between 17% and 19% of the total indicated horse power. The performance of internal combustion engines in terms of frictional power loss, fuel consumption, oil consumption, and harmful exhaust emissions is closely related to the friction force and wear between moving parts of the engine such as piston assembly, valve train, and bearings. To solve this problem, most modern research in the area of Nanotribology (Nanolubricants) aims to improve surface properties, reduce frictional power losses, increase engine efficiency, and reduce consumed fuel and cost of maintenance. Nanolubricants contain different nanoparticles such as Cu, CuO, TiO2, Ag, Al2O3, diamond, and graphene oxide. This paper demonstrates the effect of nanoparticles on the tribological behavior of the engine oil. The main objective of this review is to present recent progress and, consequently, develop an exhaustive understanding about the tribological behavior of engine oils mixed with nanoparticles.