炭纤维增强聚四氟乙烯复合材料在干摩擦和水润滑条件下的摩擦学行为对比研究

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

对比考察了炭纤维增强聚四氟乙烯(PTFE)复合材料在干摩擦和水润滑条件下的摩擦磨损性能,并探讨了其磨损机理.结果表明:在水润滑条件下,纤维增强PTFE复合材料的摩擦系数和磨损率均明显比干摩擦下的低,水起到了润滑和冷却作用;复合材料磨损表面可见明显的裸露纤维及纤维局部磨平,无明显微观裂纹,基体和纤维结合较好,磨损表面存在转移自偶件的铁,表现出犁削磨损特征;在干摩擦下,复合材料磨损表面存在大量的微观断裂裂纹,纤维发生断裂和破碎,表现出疲劳磨损特征.

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.