Base oils and formulated transmission oils for electrical vehicles: thermophysical and tribological properties

Abstract

The aim of this research is to analyze the thermophysical, wettability, and tribological properties of some base oils of different nature (synthetic and mineral), as well as of formulated oils, to find potential transmission oils for electrical vehicles. Regarding the thermophysical properties, viscosity, density, and viscosity index were analyzed. Surface tension and contact angle were also measured to obtain the wettability performance of tested lubricants. The highest viscosities were found for the PAO8 oil and the lowest for the G-III 3 base oil, while the highest densities were found for the formulated oils. Concerning wettability performance, the surface tensions of PAOs and G-IIIs rise gradually with an increase in viscosity, the surface tension being the greatest for G-III 6 and the lowest for G-III 3. Finally, in the tribological characterization, the lowest coefficients of friction and produced wear were found with the formulated lubricants, due to the presence of an additive package.