Work

Development of a high-performance lubricant based on halogen-free phosphonium ionic liquid for electrified vehicle transmissions

Year: 2025

Type: article

Abstract: Electrified vehicle transmissions impose high demands on lubricating oils due to the electrification effects caused by stray currents. Therefore, this study aims to develop a high-performance, low-SAPS lubricant by synthesizing a halogen-free phosphonium-based ionic liquid (P 888P -SP) additive that is added to PAO10 baseline oil at varying concentrations (0.5, 1.0, and 2.0 wt%). The formulated oil is then compared with a fully formulated automatic transmission fluid (ATF-EV). An SRV-IV tribometer was utilized for assessing the tribological performance at different DC levels (0, 3, 6, and 9 A) and sliding parameters. Herein, the main underlying mechanism of antiwear tribofilm formation on the electrified AISI 52100 surfaces is explored. The results demonstrated that the 2.0-P 888P -SP oil achieved a 29% and 43% decline in the coefficient of friction (COF) compared with ATF-EV oil and PAO10 oil, respectively, under triboelectrification conditions at 9 A. Furthermore, the 2.0-P 888P -SP oil decreased the wear volume of the tribosystem by 63% and 79% in comparison to ATF-EV oil and PAO10 oil, respectively. This improvement relates to the synergistic action and adaptability of the P 888P -SP additive with electrification effects. These characteristics resulted in the tribofilm formation, with thickness ranging from 839 nm to 1.41 µm, thereby enhancing the durability of mechanical components. Ultimately, the halogen-free structure of P 888P -SP contributes to its environmental compatibility, making it a promising candidate for use as a lubricant additive in electrified vehicle transmissions.

Source: Tribology International

DOI: 10.1016/j.triboint.2025.111206