Comparative Study of Tribological Behavior of Carbon Fiber Reinforced Polytetrafluoroethylene Composites at Dry- and Water-Lubricated Sliding against Stainless Steel

Carbon fiber reinforced polytetrafluoroethylene (PTFE) composite was prepared by compression molding. The friction and wear behaviors of the resulting carbon fiber reinforced PTFE composite sliding against stainless steel at dry-and water-lubricated conditions were comparatively evaluated on an MM-200 test rig in a block-on-ring configuration. The morphologies of the worn surfaces of the PTFE composite and counterpart steel were observed on a scanning electron microscope, while the chemical state of F on the worn surface of the steel sliding against the PTFE composite at dry- and water-lubricated conditions was examined by means of X-ray photoelectron spectroscopy. It was found that the incorporation of the carbon fiber contributed to greatly increasing the wear resistance of PTFE, while the water as the lubricant further significantly increased the wear resistance of PTFE and its reinforced composite. This was attributed to the load-carrying capacity of the carbon fiber and the cooling and lubricating action of the water, which considerably decreased the friction-induced heat and hence hindered the plastic deformation and breakage of the PTFE matrix by the thermal effect. The PTFE composite was characterized by severe plastic deformation, adhesion, and fatigue, as it slid against the stainless steel at dry condition, while the plastic deformation and adhesion was greatly hindered under water lubrication.