Experimental Investigation of Tribological and Rheological Behaviour of Hybrid Nanolubricants for Applications in Internal Combustion Engines

Abstract

In this study, the improvement in SAE 10W-40 engine oil tribological performance after the addition of magnesium oxide (MgO) nanoadditive and two different phosphonium-based ionic liquids (ILs) was investigated. Besides, the rheological behaviour of MgO-based nanolubricant and IL-based hybrid nanolubricants at the temperature range from 293.15 to 363.15 K was studied. The nanoparticle characterization was performed by means of transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The tribological properties, friction coefficients and wear parameters of the formulated oil modified with 0.01 wt% MgO and 1 wt% ILs compared with the neat 10W-40 oil were performed and analysed using a ball-on-three-pins tribometer and a 3D optical profilometer, respectively. Further analysis on the worn surface was shown by Raman spectroscopy and SEM images illustrating the formation of the protective IL and MgO tribo-films as hybrid additives. In friction tests with sliding steel-steel tribo-pairs, IL3-based hybrid nanolubricant decreased the coefficient of friction and wear volume by 7% and 59%, respectively, in comparison with the neat SAE 10W-40, hence better positive synergies were found for MgO and IL3 as hybrid additives. Interestingly, the thermophysical characterization by rheology also revealed that the nanoparticle and ionic liquids addition did not affect neither the viscosity response nor the Newtonian behaviour of the engine oil, adequately meeting the requirements for their use in internal combustion engines. Graphical Abstract

Irradiation Time Optimization on Photocatalytic Activity of Nanoparticles MgO from Dolomite Bangkalan

“…The vibration of the O-Mg-O bending mode was detected at the Raman number of 155.87 cm −1 [33] and at 212.53 cm −1 , which was the vibration of the MgO compound [39]. The Mg-O stretching vibration occurred at the Raman peak of 281.83 cm −1 , related to the TA phonon [36,40]. Two low-intensity peaks were observed at 712.93 and 750.56 cm −1 , which could be attributed to MgO [41].…”

“…Symmetrical stretch (A1g) occurred at the peak of 1,087.36 cm −1 , which could be associated with TO (Optical Transverse) and LO (Optical Longitudinal) phonons [31,34]. The peak of the Raman was about 446.37 cm −1 , with TA phonon with asymmetric deformation mode (Eg) [31,35,36]. The cases of T1g and T2g indicated a Raman shift above 1,000 cm −1 because they had low energy [37].…”

Investigating the Wettability, Rheological, and Tribological Properties of Ammonium-Based Protic Ionic Liquids as Neat Lubricants for Steel–Steel and Steel–Aluminium Contacts

“…When the temperature of the lubricant rises, it results in a weakening of the hydrogen bonds. Also, it reduces the intermolecular interaction between the fluid molecules, reducing the viscosity of the PILs [43,44]. Thus, a drop in the viscosities of the lubricant was reported.…”

Towards the superlubricity of polymer–steel interfaces with ionic liquids and carbon nanotubes

“…Table 1 shows that La decreases slightly from 15.0 nm to 12.2 nm, confirming that purification and functionalisation do not change the structure of CNTs significantly. This ionic liquid is a well-known oil additive with proven anti-friction, anti-wear and anti-corrosion properties [36][37][38][39][40][41]. However, its application as a liquid phase for lubricants has not been explored so far.…”