Preparation And Tribological Properties Of PEO/UHMWPE Composite Coating On Ti6A14V Alloy Surface

Titanium alloy has many advantages,such as good biocompatibility and low modulus of elasticity,but it has such problems as poor friction,low hardness and poor wettability,which largely limits its application in the biomedical field of friction and wear parts.Therefore,it is of great significance to improve the tribological properties of titanium alloys.In this paper,the antifriction and wear-resistant coatings for titanium alloys are designed from the aspects of surface texture,hard ceramic skeleton and self lubricating organic coating.Laser surface texturing(LST)technology was used to construct regular distributed microporous arrays.The effect of surface texture on abrasive particles and hydrodynamic lubrication effect under lubrication conditions were studied.The rigid wear resistant ceramic skeleton was prepared by plasma electrolytic oxidation(PEO)technology.The electrolyte proportion and technological parameters were studied and optimized,and the bearing capacity of hard ceramic coating on the whole composite coating was studied.The effect of ultra high molecular weight polyethylene(UHMWPE)as a surface self lubricating organic coating on the wear resistance of the composite coating was studied.The effect of graphene on the hydrophilicity and Tribological Properties of the composite coating was studied by using graphene to fill and modify UHMWPE.Tribological properties of titanium alloy composite coating on dry friction and water lubrication were studied.The effects of surface texture,hard straight ceramic skeleton and self-lubricating organic coating on tribological properties were discussed,and the formation and failure rule of composite coatings were analyzed.By field emission scanning electron microscopy(FE-SEM)to observe the surface morphology of composite coatings and wear scar morphology by X-ray diffraction(XRD)phase composition analysis of composite coating,measuring the hardness of composite coating by Vivtorinox,tribology experiment using pin disc friction test machine,wear rate weighing measurement of composite coating.The results show that the texture parameter optimization(diameter 200 ?m,the surface density of electrolyte,20%)optimization(NaAlO2 12g/L,Na3PO4 1.6g/L,NaOH 0.3g/L)and electrolytic parameters(initial voltage 450V,pulse frequency 400Hz,duty cycle 20%),UHMWPE coating on the surface of the composite coating performance a good wear resistance,friction coefficient is 0.06,the wear rate is 1.05×10-6mm3(Nxm)-1,compared with the titanium alloy substrate is an order of magnitude lower.The UHMWPE was modified by filling with graphene,graphene makes the adsorption of UHMWPE particles became finer,coating surface becomes more smooth and compact;hydrophilicity has been improved,adding 3 wt.%of graphene,the contact angle decreased from 80° to 60°;tribological properties under water lubrication has been significantly improved,the friction coefficient decreased to 0.03,the wear rate decreased to 0.076×10-6mm3(N×m)-1.