| Joint replacement is an effective method to treat advanced joint diseases,and PEEK is regarded as an ideal friction pair due to its excellent mechanical properties and good biocompatibility.In vitro tribological studies have found that neat PEEK(450G)has poor anti-wear performance,which is only applicable to the design of low-load coordinated joint prosthesis.Theoretically,the wear-resisting property of PEEK can be enhanced to different degrees by combining different reinforcement or solid lubricating particles,further expanding its application range.Currently,PEEK composites include carbon fiber reinforced(CA30),glass fiber reinforced(GL30)and carbon fiber/graphene/polytetrafluethylene(FC30),which are considered as potential artificial joint materials.Their wear mechanism and wear performance under physiological operating conditions need to be further studied.Therefore,based on the "pin-disc" tribological experiment,"circular" physiological sliding trajectory was adopted under the physiological lubrication condition of bovine serum,and the tribological properties of PEEK and its composite materials were tested in this paper.In addition,scanning electron microscope(SEM),energy spectrum analysis(EDS),optical microscope and Raman spectrometer(Raman)were used to observe the changes of surface microstructure,chemical composition and crystallinity of the worn surface.Based on this,the wear mechanism of PEEK composite self-mating was discussed,the actual wear reduction and anti-wear mechanism of the reinforcements was clarified,and the direct influence of physical friction process on the surface layer of friction pair was revealed.Subsequently,the tribological properties of PEEK composites coupled with traditional polymer friction pair(UHMWPE)or metal friction pair(Ti6A14V)were further studied systematically.And the feasibility of PEEK composites in the design of artificial joint prosthesis was further discussed as a comparison,so as to provide suggestions for the development of PEEK composites.The main results are as follows:(1)Tribological study of PEEK and its composite self-matingCarbon fiber reinforced PEEK is best wear resistance,with a wear factor of 1.38 ± 0.12×10-6 mm3/N·m,significantly lower than 450G,FC30 and GL30.Under physiological operating conditions,the wear mechanism of neat PEEK is mainly "abrasive-adhesion" wear.The wear morphology includes furrow,polishing,and scale-like wear marks,etc.In contrast,the wear morphology of PEEK composites also includes surface pits caused by fiber disconnection,and the wear resistance is directly dependent on the binding strength between the reinforcement and PEEK matrix.(2)Study on surface crystallinity changes before and after friction of PEEK and its composite self-matingAfter 2 Mc friction and wear test,the peak strength ratios of ether bond to benzene ring in 450G,CA30,FC30 and GL30 decreased by 4.9%,4.3%,2.5%and 3.5%,respectively.This change demonstrates that the physical friction process results in a decrease in surface crystallinity of PEEK and its composites.This phenomenon may be due to PEEK being a semi-crystalline material,a cyclic friction process leading to rearrangement and orientation softening of polymer chains.(3)Tribological study of CA30 and FC30 coupled with UHMWPE and Ti6Al4V,respectivelyWhen coupled with UHMPWE,the relatively soft UHMWPE disc shows severe wear morphology,and the wear factor is an order of magnitude higher than that of CA30 or FC30.Compared with Ti6A14V,the tribological performance was better with wear factors of 1.43±0.41×10-6 mm3/N ·m(CA30/Ti6Al4V)and 2.17± 1.12×10-6 mm3/N·m(FC30/Ti6Al4V),respectively.The results show that PEEK composites are more suitable for hard metal materials.In this thesis,the biological tribology of PEEK and its composite was studied,which provided a theoretical basis for its application in joint prosthesis design,and provided guidance for the reserch and development of PEEK antiwear composite. |
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