Tribological Performance Investigation of a Commercial Engine Oil Incorporating Reduced Graphene Oxide as Additive

Abstract

We investigated the tribological behavior of commercialized, fully synthetic engine oil upon the incorporation of reduced graphene oxide in seven different concentrations between 0.01 and 0.2 wt %. Stability of the prepared samples was assessed by turbidimetry and dynamic light scattering measurements, and their tribological properties through a reciprocating tribometer, using a steel ball on special cut steel blocks. The addition of 0.02 wt % of reduced graphene oxide led to an improvement of the tribological behavior compared to the pristine engine oil, by significantly lowering the friction coefficient by 5% in the boundary lubrication regime. Both the surfaces and the reduced graphene oxide additive were thoroughly characterized by microscopic and optical spectroscopy techniques. We also verified that a protective layer was formed between the worn surfaces, due to the presence of reduced graphene oxide. Carbon accumulation and various additive elements such as Ca, Zn, S and P were detected on the rubbing surfaces of both the ball and the block through energy-dispersive X-ray spectroscopy. Finally, it was shown that the wear scar diameter on the surface of the steel ball was lower by 3%, upon testing the engine oil sample containing reduced graphene oxide at concentration 0.02 wt %, compared to the control sample.

Experimental investigation of the effect of tribological performance of reduced graphene oxide additive added into engine oil on gasoline engine wear

“…Figure 1 shows 5W40 reference oil and the prepared “hybrid” nanolubricant 5W‐40 containing 0.02 wt% rGO, remained stable for more than 6 months as mentioned in our previous work, 1 while it resulted in lower COF compared to the reference 5W‐40 engine oil by 3.29%, as estimated with the use of a tribometer. Reduced Graphene Oxide analysis such as ATR FT‐IR absorbance, Raman spectra, Turbidimetry Measurements, size and zeta potential measurements were reported in our previous work.…”

Chemically functionalized graphene oxide with N‐phenyl‐p‐phenylenediamine as efficient tribo‐ and rheological modifier for lubricating oil

“…In addition to lubricating oil, additives increase the oil's efficiency by forming the protective boundary film with low shear providing additional safety. 1 Therefore, reducing friction implies saving fuel, while a decrease in wear means longer durability. 2 Due to these additives and lubricants, mechanical strength and the lifetime of the engine increase.…”

“…Engine oils can easily separate the metal‐to‐metal contact surfaces by reducing friction and wear, depending upon the sliding speed and other operating conditions. In addition to lubricating oil, additives increase the oil's efficiency by forming the protective boundary film with low shear providing additional safety 1 . Therefore, reducing friction implies saving fuel, while a decrease in wear means longer durability 2 .…”

Recent Advances in Preparation and Testing Methods of Engine-Based Nanolubricants: A State-of-the-Art Review

“…Nanomaterials have been studied intensively as additives for promoting lubricant capabilities. The application of nanoparticles in the engine's lubrication system showed a great deal of boosting the overall engine performance in many studies [20][21][22][23][24]. Nanolubricants have a major effect on promoting the wear process, which is the durability of the engine parts, with a considerable role in engine thermal efficiency [25].…”