Growth and characterization of tantalum multilayer thin films on CoCrMo alloy for orthopedic implant applications

In this study, tantalum (Ta) thin films deposited (by magnetron sputtering) on CoCrMo alloy substrates were studied using X-Ray Diffraction, Scanning Electron Microscopy and Rockwell C indentation tests. The results show that α-Ta single phase thin films, the desired phase for orthopedic implant applications, with low adhesion forms at substrate temperature of 400 °C or above while a mixture of α-Ta and β-Ta forms at substrate temperature lower than 400 °C. A negative bias of 78 V applied to substrate results in development of adherent β-Ta thin film at room temperature. Based on the results, a multilayered gradient Ta thin film, β-Ta/β-Ta + α-Ta/α-Ta, with controlled structure has been developed on biomedical CoCrMo alloy sheets. The film shows high adhesion, which is promising for biomedical applications.