Interfacial Structure and Tribological Property of Adsorbed Layer Formed by Dibasic Acid Ester Derivative

An investigation was conducted of the low-friction and low-wear mechanism of the adsorbed layer formed by dibasic acid ester derivative. First, the film thickness and film density of the adsorbed layer on an iron surface was evaluated by neutron reflectometry. The density of the adsorbed layer formed at 25°C was twice that at 100°C. The macroscale tribological properties of an adsorbed layer formed by dibasic acid ester derivative and its constituent additives (succinic acid and amine) were evaluated using a ball-on-disk tribometer at 25°C and 150°C. The derivative exhibited low friction and wear properties even at high temperature. To clarify the mechanism of the excellent low friction property, nanoscale tribological testing was conducted using an atomic force microscope. The precise measurement indicated that the dibasic acid ester derivative initially exhibits low friction due to generation of metal soap from the amine, and then subsequent friction generates metal soap from the succinic acid that has superior friction reduction performance, which promotes lower friction, especially under low-contact-pressure sliding conditions.