Research on the surface characterization, corrosion and bioactivity of nano-featured tantalum coating on selective electron beam melted Ti6Al4V alloy

A nano-featured tantalum coatings with an average thickness of 800 nm and grain size of 50 nm were successfully prepared by Selective Electron Beam Melted (SEBM) Ti6Al4V substrates by DC magnetron sputtering technology. The details of the physicochemical properties, corrosion resistance and in vitro biocompatibility of the coating were systematically investigated. Elastic modulus of the nano tantalum coatings was around 123.8 GPa and the hardness was 8.08 GPa. Compared with uncoated Ti6Al4V matrix, the corrosion potential of the Ta-Ti64 samples was positively shifted and the corrosion current density decreased from 2.07 × 10⁻⁷ to 2.85 × 10⁻⁸ A·cm⁻² (0.1 mV/s). EIS and PDP results show that the coating enhances the humoral corrosion resistance of Ti6Al4V, which can provide active protection for the substrate to prevent the release of toxic ions caused by long-term corrosion. The mouse osteoblast cell line (MC3T3-E1) is applied in this study for biological evaluation. The optical density at 450 nm results showed that the cell proliferation rate of tantalum coated surface was faster than that of Ti6Al4V sheet and pure tantalum sheet. The 5-day cell adhesion density is 1.26 and 1.32 times higher than uncoated Ti6Al4V and pure tantalum respectively. The nano-structured Ta layer significantly improved the initial adhesion of MC3T3-E1 cells and promoted cell proliferation. The corrosion resistance and biocompatibility of Ta coating are not only better than titanium matrix, but also better than pure tantalum. The results prove that tantalum coating is an effective method to modify titanium alloy and holds a great potential value on 3D printed personalized implants application.