Abstract
Owing to the significance of improving fuel economy, reducing emissions, and extending the durability of engine components, this study focused on the tribological performance of nano-additives. In this study, copper (Cu) and graphene (Gr) nanomaterials were dispersed in a fully formulated engine oil (5W-30) with different concentrations. The tribological trials were investigated under various speeds and loads, utilizing a reciprocating tribometer to mimic the ring/liner interfaces in the engine. The frictional surface morphologies were comprehensively analyzed using electron probe X-ray microanalysis (EPMA), field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), and three dimensional (3D) surface profilometry to explore the mechanisms responsible for improving the tribological performance of the frictional sliding parts in the engine. The tribological test results illustrated that lubrication by nano-additives reduced the wear rate (WR) and friction coefficient (COF) by 25%–30% and 26.5%–32.6%, respectively, as compared with 5W-30. The results showed that this is a promising approach for increasing the durability and lifespan of frictional sliding components and fuel economy in automobile engines.
Highlights
The current challenges in automobiles engines for improving the tribological performance and extending the durability of frictional sliding components require novel lube oils that readjust to various operating circumstances [1,2,3]. 90% of the lube oils sold commercially compose of hydrocarbon molecules, and the rest are additives that govern performance [4]
The COF was calculated in situ by measuring the frictional force that was divided by the applied load while the wear rate (WR) of the rubbing samples in mm3·N−1·m−1 was quantified by measuring the wear volume
The results indicated that the the average COF of the nanolubricants containing Cu and Cu/Gr nanomaterials decreased versus contact loads and sliding speeds, by as much as 17.3%–23.6% and 26.5%–32.6%, respectively, compared with the reference oil
Summary
The current challenges in automobiles engines for improving the tribological performance and extending the durability of frictional sliding components require novel lube oils that readjust to various operating circumstances [1,2,3]. 90% of the lube oils sold commercially compose of hydrocarbon molecules, and the rest are additives that govern performance [4]. The current challenges in automobiles engines for improving the tribological performance and extending the durability of frictional sliding components require novel lube oils that readjust to various operating circumstances [1,2,3]. Based on the experimental tests by Padgurskas et al [25], the Cu nano-additives are more effective in mixed and boundary lubrication than in full film lubrication This indicates that the potential interaction of the rubbing surfaces is necessary for the formation of Cu tribofilm and its tribological performance. Few studies have focused on the major mechanisms serving to improve the tribological behavior of the piston ring-cylinder liner contact in the engines. The aim is to provide the main reasons and explanations how nanolubricants can assist in extending the durability of the frictional interfaces in automobile engines under different circumstances
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