Research On Tribological Propertites Of Nano-serpentine/La₂O₃ Modified PTFE Under Seawater Lubrication

With the rapid development of ocean engineering,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 solve the problem.Compared with dry friction environment,there are fewer studies on tribological properties of nano-materials filled polymers under seawater.Therefore,it is of great practical significance to study the tribological properties of the composites under seawater lubrication.Polytetrafluoroethylene（PTFE）matrix composites have become the research hotspot of tribological properties of composites due to its excellent low friction,light weight,corrosion resistance and other excellent properties.In this paper,PTFE-based were filled with nano-La₂O₃ and nano-Serpentine（PTFE/SL）,five sets of composites with different contents were designed by uniform design method and prepared by means of vacuum hot pressing technique,and 316 L stainless steel as the metal spouse pair.Water absorption rates and mechanical properties were tested to compare the hardness and tensile properties of the composites before and after immerged in seawater.The friction coefficient and wear rate of the composites under different working conditions（load and rotating speed）in seawater were studied with friction and wear testing machine（MMU-5G）for experimental study.Transmission electron microscopy（TEM）and scanning electron microscopy（SEM）were used to evaluate the worn surface morphology and the tribological mechanism of the PTFE/SL ternary composites and its metal spouse pair under seawater lubrication.Tribological experiment of PTFE-based composites showed that the tensile strength of the composites decreased slightly while its hardness was improved.The properties of antifriction achieved the best when total filling content of the filler is 12%（Serpentine is 8% and La₂O₃ is 4%）.Tribological experiment of PTFE/SL ternary composites under different working conditions（load and sliding speed）showed that,the main wear mechanism of the composites are abrasive wear and slight fatigue wear.A large amount of free water,active two particles of active oxygen and（Si-O/Mg-O）attached to transfer film were produced due to the chemical reaction of the friction heat of the PTFE composites and produced synergy with seawater lubricant film,which effectively improved its anti-friction and anti-wear properties.The experiment shows that the suitable working conditions were medium load and high rotating speed.