Evaluating fuel lubricant additives – Relating the nano to the macro scales

Abstract: Organic friction modifiers (OFMs) as fuel lubricant additives have been researched in great detail since their discovery in the early 1920’s. Industrially fuel lubricity is evaluated using rapid bench-top testing most notably the high frequency reciprocating rig (HFRR) being an ISO standard method. Some research questions the ability of these methods to evaluate, distinguish and better understand OFMs in fuel.

In the present work, we used a wide variety of nanotribological techniques (AFM and Langmuir trough) to develop fundamental understanding of the molecular factors affecting the OFM performance, which was subsequently correlated to macroscale tribological testing. This multiscale approach decouples the lubrication mechanisms that underpin OFMs design. There are two primary factors for OFM functionality: interfacial equilibrium performance and the kinetics factors of the adsorption processes.

Building upon the method and the understanding established, it is now feasible to purposely design the molecular characteristics of OFMs, meeting the needs of the operational environment.