24th International Colloquium Tribology - January 2024 67 Surfactant Systems with Improved Lubricity for Water Miscible Cooling Lubricants Ludger Bösing 1 und Arjan Gelissen 1 1 Sasol Germany GmbH, Marl, Germany 1. Introduction Surfactant lubrication systems with thickening properties at higher temperatures and improved lubrication were investigated. The study focused on observed thickening phenomenon in nonionic surfactant-based lubricants. Experimental analysis reveals temperature-induced structural changes in the nonionic surfactant molecules, forming a gel-like network within the lubricant. This network enhances viscosity and load-carrying capacity. Comparative tests demonstrate superior lubrication properties of the nonionic surfactant system, including reduced friction, wear, and improved film formation at higher temperatures. The three-dimensional network provides boundary lubrication and prevents metal-to-metal contact, while increased viscosity ensures effective surface separation. This research contributes to the understanding of nonionic surfactant-based lubricants, facilitating the development of tailored rheological properties for high-temperature applications, improving machinery efficiency and durability. 2. Conclusion It has been found that surfactants, when aggregating in their lamellar liquid crystalline form (L α ), provide good lubrication of surfaces. The conditions for obtaining lamellar liquid crystalline phases at surfaces depends besides the surfactant molecular structure itself mainly on the concentration and temperature. These dependencies are depicted in binary phase diagrams. Alcohol ethoxylates are typically in their L α -form at elevated concentrations of 50 to 70 wt% (Picture No. 1). The target to achieve a maximum area of lamellar phases (lubricating areas) was investigated on different nonionic surfactant systems. To be more effective, focus was placed on lower application concentrations. One phase behaviour is shown in picture No. 2. Picture 1: Example phase behaviour of a standard nonionic surfactant Picture 2: Phase behaviour of a standard nonionic alkoylate References [1] Kronberg B. How to Design a Surfactant System for Lubrication. In: Biresaw G, Mittal KL, editors. Surfactants in Tribology. Boca Raton, FL, USA: CRC Press; 2008. P.327-329 [2] Carrion F-J, Martinez-Nicolas G, Iglesias P, Sanes J, Bermudez M-D. Liquid Chrystals in Tribology, International Journal of Molecular Sciences. 2009