Thermophysical properties of polyalphaolefin oil modified with nanoadditives

Abstract

This article presents an experimental investigation on the effects of concentration and morphology of nanoadditives on the thermophysical properties of nanolubricants (NLs) at different temperatures. A polyalphaolefin (PAO6) oil was used as base fluid. A two-step method was used to prepare the NLs. Zirconium oxide (ZrO2) and boron nitride (BN) nanoparticles (NPs) and graphene nanoplatelets (GnP) were separately dispersed in the base fluid with mole fraction ranging from 0.05 wt% to 2 wt%. The NPs and GnP were characterized by X-ray diffraction, Raman spectroscopy and electron microscopy. The base oil was also analysed by mass spectrometry. Visual sedimentation, temporal variation of refractive index and Fourier transform infrared spectroscopy were used to analyze the stability of the nanolubricants and the existence of new interactions between nanoparticles and base oils. Detailed study was carried out to analyse the effect of nanoadditives on viscosity, density and adiabatic bulk modulus. Moreover, different predictive equations to estimate termophysical properties were tested using the experimental values. Pressure-viscosity coefficients as a function of the temperature and nanoparticle concentration were predicted for all the nanolubricants.