Stability and tribological performance of dispersed graphene (Gr) and aluminium nitride (AlN) nanoparticles in mineral oil

Abstract

Nanolubricants can give a solution to a variety of concerns with traditional lubricants. A good nanolubricant is expected to be stable without sedimentation for an extended period in order to provide good heat transfer and not degrade performance owing to nanolubricant instability. In this study, the stability of mono nanolubricants consists of graphene (Gr) and aluminium nitrite (AlN) in SUNISO 3GS compressor oil and PETRONAS SYNTIUM 500 15W-40 engine oil, in 0.05, 0.075 and 0.1 vol% concentration, without and with surfactant is investigated. The surfactants used in this study are CTAB and SPAN 80 for Gr and AlN, respectively. This study also investigates the difference of base fluid and how it affects the performance of the nanolubricants. Not only that, previous studies investigated the same type of nanoparticles however in this study, Gr and AlN are two different class of nanoparticles which are carbon and ceramic based nanoparticles, respectively. The stability of nanolubricants is investigated using visual observation method, thermal conductivity (TC) measurement and UV–vis spectrophotometer. Furthermore, rheological properties (viscosity, viscosity index and flash point) and tribological properties of nanolubricants are studied. The highest percentage difference for TC is 22.58 in comparison with pure compressor oil. Lastly, by using pin-on disc tribotester, it can be observed surfactant in nanolubricants reducing the specific wear rate (SWR) and the highest percentage difference is high as 76.37 % for nanolubricant. The final observation shows that GR (0.05)-CO(CT) and GR (0.05)-EO(CT) have the best performance among all nanolubricants.