Biotribological And Corrosion Behavior Of PEEK/UHMWPE/CoCrMo Artificial Joint Pairs

Under the action of cyclic alternating load,there is not only wear behavior,but also corrosion and other comprehensive effects due to the presence of metal after the artificial joint is implanted into the human body.As a new bone biological material,PEEK has a modulus of elasticity close to that of cortical bone.It has the characteristics of "plasticizing steel" and its performance is comparable to that of metal materials.Therefore,PEEK may replace metal joint materials in the joint field,and form a new type of joint with the UHMWPE.In this paper,three typical joints of PEEK/UHMWPE,CoCrMo/UHMWPE and CoCrMo/PEEK were selected to study their twisting,swinging and sliding biological tribological behaviors.Meanwhile,the corrosion characteristics of CoCrMo/UHMWPE and CoCrMo/PEEK were discussed.The main conclusions are as follows:When PEEK/UHMWPE pair is under the twisted friction conditions,the greater the twisting angle is,the smaller the friction coefficient will be.When the normal load is 1600 N,the friction coefficient is the smallest,the normal load is increased and decreased,and the friction coefficient is increasing.Under the swing condition,the friction coefficient increases with the increase of the swing angle and the normal load.Under the condition of twisting and swinging,the wear of high-crosslinking UHMWPE increases with the angular displacement amplitude,normal load and cyclic times.The material loss under the oscillating motion is the most serious.Under the same load condition,the wear amount is higher than that under the twist motion.The T-? curve has three shapes with the increase of the twisting angle,which changes from linear to elliptical and parallelogram.The corresponding twisting and fretting running state is changing from the elastically coordinated partial slip to the plastic slip.Under different normal load conditions,the T-? curve is always elliptical,and the twisting motion state is in the mixing zone.When the twisting angle is small,the frictional dissipation energy is almost zero,and when the frictional load increases with the normal load,the energy is gradually increasing.With the increase of the twisting angle,the wear of the material is gradually increased.The wear mechanism of the UHMWPE is mainly abrasive wear and slight adhesive wear.The wear mechanism of PEEK is mainly abrasive wear.Under the oscillating condition,the surface of the UHMWPE is slightly worn,the wear mechanism is abrasive wear and fatigue wear,and the wear mechanism of PEEK is abrasive wear and adhesive wear.The friction coefficient of UHMWPE/CoCrMo with the pair in the initial stage of sliding wear test increased sharply then stabilized,and the load had little effect on the friction coefficient.PEEK/CoCrMo with a pair has a maximum coefficient of friction at small loads,and a larger load results in a lower coefficient of friction.The smaller normal load has a significant influence on the friction coefficient of the PEEK/UHMWPE pair.As the load increases,the friction coefficient increases and the friction coefficient increases.The wear of the first two types of joints increases with the increase of normal load and wear time.The wear volume of “soft-to-soft” with high-crosslinking UHMWPE is gradually increased with the increase of normal load.Among the three friction pairs,the wear pit of CoCrMo/PEEK is the deepest,but the wear scar width is the shortest.The scaly peeling layer caused by the adhesion of the contact surface can be observed on the surface,accompanied by the furrow.The damage mechanism of PEEK is mainly abrasive wear and adhesive wear.The wear volume of CoCrMo/UHMWPE is the largest,the material loss is the most serious,there is a large amount of wear debris on the edge of the furrow,and obvious fatigue cracks and tears can be observed.The damage mechanism of UHMWPE is mainly abrasive wear and fatigue wear.The wear scar of the PEEK/UHMWPE wear surface is slight,and there are only a small amount of cracks and lamellar peeling caused by adhesive wear.Due to the influence of the passivation film on the surface of CoCrMo between the two pairs of CoCrMo/UHMWPE and CoCrMo/PEEK,the corrosion current is small at the beginning of the experiment.With the progress of friction,the corrosion rate gradually increases and then reaches a stable stage.The experimental results show that with the increase of wear time and load,the polarization curve will shift to the left,the corrosion tendency will increase,and the wear will tend to increase.