A Comparative Investigation of the Tribological Behavior and Wear Mechanism of Bronze-graphite Composite under Dry- and Water-lubricated Sliding against Steel

The friction and wear behavior of bronze-graphite composite under dry- and water-lubricated sliding against a stainless steel was comparatively investigated with an MM-200 friction and wear tester. The wear mechanisms of the composites were examined as well based on scanning electron microscopic and X-ray photoelectron spectrometric analyses of the worn surfaces of the composite and counterpart. As the results, the composites registers lower wear rate and higher friction coefficient under water lubrication at a relatively smaller sliding speed. Little difference in the friction coefficient and wear rate is observed for the composite under both dry- and water-lubricated conditions as it slides against the steel at a relatively higher sliding speed. The composite is characterized by adhesion wear and scuffing under dry sliding, while it is characterized by abrasion and fatigue under water-lubricated sliding. The cooling effect of water helps to abate the surface temperature rise and restrain the adhesion and transfer. This contributed to decrease the wear rate. Though the oxidation of the counterpart steel was enhanced by water as the lubricant medium, the resultant generation of a compact oxide film contributes to restrain the adhesion and transfer and hence reduce the wear rate of the frictional pair.