Mechanism of friction reduction of unsaturated fatty acids as additives in diesel fuels

Abstract

Abstract This paper investigates the effect of unsaturated fatty acid additives on the lubricating properties of a biodiesel, composed of a blend of fatty acid methyl esters (FAMEs) and a conventional diesel fuel. The presence of fatty acids as additives for biodiesel improves their lubricating properties at elevated temperature conditions. The formation of a protective lubricating tribochemical film on the steel contact surfaces has been evidenced. Elevated temperature conditions and possibly oxygen are needed to form this film that reduces friction and limits wear. Several analytical tools have revealed the insulating nature of the formed tribofilm and its chemical properties. Friction-induced reticulation is thought to play a major role in the growth of this insulating film.