Tribo-catalysis triggered the in-situ formation of amphiphilic molecules to reduce friction and wear

Abstract

A coating composed of Au/Ag/Cu was deposited onto steel surfaces to catalyze the tribochemical reaction of polyalphaolefin (PAO), resulting in the formation of amphiphilic molecules. The coated surface showed a reduction in friction coefficient and wear track width by 24.9∼43.0% and 61.4∼68.9%, respectively, compared to the bare steel surface. The in situ formed amphiphilic molecules were chemically bonded on tribopair surface after deprotonation, and then formed a tribofilm. This tribofilm exhibited low interfacial adhesion at nano scale, contributing to low friction and wear. Density functional theory simulations reveals that the dissociation energy of C-H bond on Au surface was much lower than that on iron surface, favoring the catalytic oxidation reaction of PAO into amphiphilic molecules.