Microstructure and Properties of Monolayer Ta and Multilayer Ta/Ti/Zr/Ta Coatings Deposited on Biomedical Ti-6Al-4V Alloy by Magnetron Sputtering

Two types of coatings, i.e., monolayer Ta and multilayer Ta/Ti/Zr/Ta coatings, were deposited on biomedical Ti6Al4V (TC4) alloy by magnetron sputtering to improve its performance. To evaluate the effect of the two coatings on the alloy properties, the microstructure, composition, mechanical and tribological properties, in vitro biocompatibility, and corrosion resistance were investigated. The results showed that α-Ta exists in the monolayer Ta coating, while α-Ta and β-Ta phases coexist in the multilayer Ta/Ti/Zr/Ta coating. The multilayer Ta/Ti/Zr/Ta coating possessed the highest hardness and the monolayer Ta coating had the lowest friction coefficient compared to the Ti6Al4V alloy. The friction and wear tests revealed that the anti-wear performance of the Ta coating is the best, followed by that of the Ta/Ti/Zr/Ta coating, while the anti-wear performance of TC4 alloy is relatively poor in comparison with the Ta and Ta/Ti/Zr/Ta coatings. The wear resistance of the multilayer Ta/Ti/Zr/Ta coating under low normal load is better than that under high load normal load. Finally, the in vitro and electrochemical corrosion tests showed that the Ta coating modification provides better biocompatibility and corrosion resistance than those of the uncoated Ti6Al4V alloy.