Research On Tribological Propertites Of Nano-serpentine Modified PTFE Under Seawater Lubrication

With the rapid development of ocean engineering, A series of problems such as the marine environment pollution has caused widely public concern. Metal materials applied to the frictional pairs of marine engineering equipment are gradually taken place by plastics in order to better protect the marine environment. Polytetrafluoroethylene(PTFE) matrix composites has become the research hotspot of tribological properties of composites under dry friction due to its excellent corrosion resistance, light weight, low friction, but the research of its friction and wear performance under natural seawater lubrication is rarely reported. The study on tribological properties of PTFE-based composites under seawater lubrication has practical engineering significance and will enrich the ocean tribology theory.In this paper, PTFE-based filled with nano-Serpentine to prepare PTFE/Serpentine composites by means of hot pressing technique and 316 L stainless steel as the metal spouse pair. The influence of content of nano-Serpentine and before and after surface modification of nano-Serpentine on the physical, mechanical properties in seawater and the tribological properties of PTFE/Serpentine composites under seawater lubrication were systematically investigated. Based on these investigations, the tribological properties of PTFE/Serpentine composites with best content of surface modification nano-Serpentine were studied in different working conditions(load and sliding speed) under the seawater lubrication. Scanning electron microscopy(SEM) and energy dispersive spectrum(EDS) were used to analyze the worn surface morphology and the tribological mechanism of the PTFE/Serpentine composites and the metal spouse pair under seawater lubrication.Research results showed that, the hardness and the seawater absorption rate of PTFE/Serpentine composites were gradually increased, but the tensile strength was decreased with the increase of content of nano-Serpentine before and after nano-Serpentine surface modification. The plasticization caused by seawater absorption and the decline of hardness were was not the main reasons that influenced PTFE/Serpentine composites tribological properties under seawater lubrication. The seawater absorption rate, hardness, tensile strength and tribological properties of PTFE filled with surface modified nano-Serpentine were better than those of PTFE/Serpentine composites without modification, especially the wear resistance got a significantly improvement. The comprehensive performance of PTFE/Serpentine composites with 15% surface modified nano-Serpentine was the best. The main wear mechanism of PTFE and its composite for were abrasive wear and plastic deformation in different levels under the condition of the water lubrication. Mg(OH)2 and Ca CO3 generated by PTFE/Serpentine composites in the friction chemical reaction can be adhered to the transfer film to improve its tribological performance significantly under seawater lubrication. Under seawater lubrication, tribological properties of PTFE/Serpentine composites with 15% surface modified nano-Serpentine were different under different loads and sliding speed and the suitable working conditions of the PTFE/Serpentine composites were low/mild load and mild/high sliding speed.