Electrified tribological study of bio-derived lubricants for electromobility applications

Abstract

Climate change has forced humanity to develop less harmful alternatives to the environment. Electromobility has then increased in popularity, aiming for humankind's greener and climate-neutral future. Nevertheless, the complete change in the vehicles’ driveline caused different complexities, including tribological problems; therefore, new lubricants should fulfill the requirements needed in the XXI century’s transportation. Moreover, stray currents and induced voltage are inevitable. Hence, new lubricants must have good electric properties that do not hinder their lubricity capability due to these harsher conditions. In addition, conventional lubricants and their additives harm the environment and human health during production, usage, and disposal. A considerable amount of used lubricants end up polluting different ecosystems and potentially affecting biodiversity and health. If the power source of vehicles is becoming greener, so should their components, and the lubricants are not an exception. Bio-based lubricants come from renewable resources, are biodegradable, and are less toxic to the environment and human interaction. Nevertheless, not all bio-lubricants can be considered sustainable since they could give rise to a conflict, economic and ethical, with food production. This research evaluates the performance of two non-edible bio-based lubricants, neat Jatropha curcas, and Micro-algae oils, and used them as additives of Mineral Group II and synthetic PAO 4 oils, respectively, at low volumetric concentrations of 5 and 10%, by characterizing their physicochemical properties and assessing their tribological performance in a four-ball tester, which was modified to run electrified trials to emulate the conditions in which they would operate in an electric vehicle’s powertrain.