Investigation of mechanical and tribological properties of multilayer surface coating of astm f-75 cocrmo alloy used as implant material

Being biocompatible and/or possessing essential initial mechanical properties aren't being sufficient for biomaterials due to their variable mechanical conditions and tribocorrosive work environment. Therefore, when selection of biomaterials, excellent corrosion and wear properties are required, furthermore especially in case of using as a joint component requires low friction coefficients and in case of using as load-bearing material high stiffness and strength is required. Therewithal, metal ions which are released from biomaterials and their compounds that occure as a result of electrochemical reactions with the body fluid; cause to loosening of the prosthesis by harming tissues and their surroundings. Since it's difficult for biomaterials to have all these desired properties together, additional alloying and surface coating processes are applied to them. In this study, in order to enhance the tribocorrosive and mechanical properties and also to decrease the metal ion release levels of the ASTM F-75 CoCrMo alloy used as knee implant material widely, multilayer thin film coating of its surface had been performed with a coating architecture of TaN/Cr, TaN/CrN/CrCN/Cr and TaN/3(CrN/CrCN)/Cr via Closed Field Unbalanced Magnetron Sputtering System. In order to examine the microstructure of the coatings SEM, EDX and XRD analysis were performed. Scratch, Pin-on-disk wear testing and hardness measurements were performed for investigate the tribological properties of the coatings. Results showed that the coatings have excellent adhesion properties. Also, very low coefficient of friction values were obtained as a result of multilayer coating. Keywords: Biomaterial, Thin Film Coating, Physical Vapor Deposition (PVD), Wear, Tribology