Abstract
Fatty acid methyl esters (FAMEs, the primary components of biodiesel) can improve the lubricity of low-sulfur diesel (LSD); however, detailed investigations into biodiesel components with various chain lengths (e.g., short-chain FAMEs) are rarely discussed. Additionally, the complex lubricity behavior with FAMEs containing free fatty acids or antioxidants is unknown. Our results showed that lauric acid methyl ester brings limited fuel lubricity improvement to LSD. The presence of fatty acids and antioxidants facilitated the formation of different frictional products on wear tracks or eliminated wear-resistive products. We further interpret fuel lubricity results by resolving kinetic features of measured electrical contact resistances and chemical composition profiles within wear tracks from standardized tests. Beyond understanding how oxygenated compounds affect fuel lubricity, we expect that the analytical approaches demonstrated in this work can shed light on other fuel lubricity related problems.
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•Electrical contact resistance values as a function of time provide insights into tribochemical reaction kinetics relating to fuel lubricities.•Synthetic antioxidants and short-chain fatty acids in fatty acid methyl esters (FAMEs) degrade low-sulfur diesel fuel lubricity.•Synthetic antioxidants tend to generate an iron-organic complex that inhibits wear-resistive tribofilm formations.