Investigation of tribological properties of composite C60-LB films

Abstract

Composite C60-LB films were fabricated by the Langmuir-Blodgett (LB) technique, their micro-structures, micro-and macro-tribological properties were investigated using atomic force microscope/friction force microscope (AFM/FFM). The results showed that in the confined C60-LB films there were two kinds of structures for the special C60 assembly: grain diameters of one kind were in the range of 150–230 nm; the other was smaller than 20 nm. Micro-tribological studies showed that topographical images of tiny C60 aggregates (<20 nm) were consistent with their frictional ones very well, namely, low friction occurred on tiny C60 aggregates compared with fatty chains LB monolayer, and ‘Micro-rolling effect’ was apparent; but for big large ones frictional forces were relatively high and ‘ratchet mechanism’ was seen apparently. Macro-tribological data proved large C60 aggregates had wear resistance and load-carrying capacities and anti-wear lives for composite C60-LB films were prolonged greatly with dispersibility of C60 improved and its grain diameter reduced. Tiny C60 aggregates were mainly the lubricating agents. Friction coefficients of composite C60-LB films gradually reduced with loads increasing having the same friction coefficient-load relations with boundary lubrication films.