Tribological Behavior of Surface-Modified Titanium and Polytetrafluoroethylene-based Composites in Seawater

In order to improve the wear resistance of Ti6Al4V titanium alloy contacted with polytetrafluoroethylene-based composites in seawater, plasma nitriding (PN), micro arc oxidation (MAO) and plasma spray tungsten carbide (PSTC) were used to modify the surface of Ti6Al4V alloy. The tribological properties of Ti6Al4V alloy matrix and its modified layers sliding with polytetrafluoroethylene-based (PTFE) composites in seawater were comparatively investigated. The PTFE composites were made with glass fiber, graphite and bronze separately by compression molding. The results indicate that low friction coefficients were shown in modified layers of the titanium alloy sliding with PTFE composites in the seawater environment. The Ti6Al4V alloy exhibits poor wear resistance and leads to the serious wear of PTFE composites. The above three kinds of surface treatments improve effectively the wear resistance of Ti6Al4V alloy. The PN treatment with reducing the wear of PTFE composites shows better wear resistance than the MAO treatment with accelerating the wear of PTFE composites. The glass fiber reinforced PTFE shows better wear resistance than the bronze reinforced PTFE in the same experimental condition. It has obvious advantages that the titanium alloy with PN treatment contacted with glass fiber reinforced PTFE were chosen as the materials of the tribological components used in hydraulic transmission in the marine environment application.