Corrosion Behavior of Ti-6Al-4V Implant Coated with a Tantalum Nanolayer for Medical Applications

In this study, Ti-6A1-4V alloy was coated with a 200 nm thick tantalum nanolayer using physical vapor deposition method with electron beam in order to improve its surface and corrosion properties. The surface hardness and roughness of the control sample (Ti-6A1-4V) and those with tantalum coating (Ti-6Al-4V/Ta) were assessed. After coating, the surface hardness and roughness of the samples increased from 345 HV to 371 HV and from 0.055 µm to 0.107 µm, respectively. Moreover, the corrosion test in Hank's solution revealed that the corrosion current density of Ti-6Al-4V/Ta decreased from 1.9 µA/cm2 vs. 0.7 µA/cm2 for control sample. Following the corrosion test, the release rate of V, Al and Ti ions was examined. The results showed that the concentration of the released elements was halved after coating. Finally, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDS) were conducted to determine the phases, microstructures, and percentage of elements in the samples, respectively. The test results indicated that tantalum-coated Ti-6A1-4V alloy has desirable corrosion resistance and excellent mechanical properties and can thus be employed in dental and orthopedic implants.