Study On The Preparation And Tribological Properties Of Porous Polyetheretherketone Self-lubricating Materials

Pure PEEK have disadvantages include of high friction coefficient,low heat distortion temperature.The high friction coefficient leads to heating quickly,thermal conducting difficultly,heat accumulating seriously.In order to reduce the friction coefficient,and solve the serious heat accumulating problem in the friction process,researchers use modification treatment such as solid lubricant,fibers and particles to blend and fill with the PEEK.Even some researchers use enhancing modification such as Nanoparticles or micron particles to blend with PEEK,which reduce the friction coefficient,increase the wear resistance of materials.However,it still can not meet the requirements of using under high temperature,high load,corrosion resistance,wear resistance.In view of this situation,this research mainly includes the following points:Porous Polyetheretherketone(PEEK)sweat gland self-lubricating materials were prepared by mold-leaching and impregnating grease or oil under high temperature and vacuum conditions.The tribological behaviors were investigated under different stress,NaCl contents and lubriating greases,respectively.The results indicate the optimal pressure and NaCl content are 100MPa and 30wt.%,respectively.The lowest wear rate was obtained when it was impregnated with lithium-base grease,which is 2.73 × 10-16m3/Nm at the load of 200N.At this time,the wear resistance increased by 1245 times when it was compared with that of pure PEEK under dry condition.Moreover,it was enhanced by 32 times comparing with that of classical CF reinforced PEEK composites.It is found that pores in PEEK composites can reserve lubricated grease.The porous self-lubricating PEEK materials can form steady and continous oil lubricating layer on the counterface,so that the friction coefficient and wear rate decreased effectively.Hierarchical porous PEEK self-lubricating composites were prepared by mold-leaching and vacuum melting process under high temperature condition.The tribological behaviors of porous PEEK composites and the synergism as a result of the incorporation of both the micro-porogen(NaCl)and mesoporous titanium oxide whiskers were investigated.In case of the micro-porogen only,the lowest steady state wear rate was observed for PEEK + 30%NaCl composite.On the base of this porous PEEK composite,the effects of mesoporous titanium oxide whiskers and non-perforated titanium oxide whiskers on the friction and wear properties of PEEK composites were comparatively studied respectively.Results showed that nano-micro porous PEEK composites with 30wt.%micro-porogen and 5 wt.%mesoporous titanium oxide whiskers reached the lowest friction coefficient and wear rate,which were recorded as 0.0194 and 2.135×10-16m3/Nm under the load of 200N.Compare with pure PEEK and classic carbon fiber-reinforced PEEK composite under dry condition,the wear resistance increased by 1593 and 41 times respectively,showing outstanding wear resistance.Scanning electron microscopy(SEM),X-ray Diffraction and BET were used in this work for better understanding of tribological properties.Owing to nano-micro porous PEEK has large internal micron pores which can store lubricant and grease,and mesoporous titanium oxide whisker connects up the large micron pores by nano pores of its own.Therefore,during the sliding process,it can form a stable lubricant film on friction surfaces,which ultimately decrease friction coefficient and increase wear resistance of PEEK composite.