Surface Modification of the Ti-35Nb-7Zr-5Ta Bio Alloy by the PM-EDM Route

Abstract

One of the most attractive β-Ti alloys is Ti–35Nb–7Zr–5Ta wt% (TNZT) alloy, which has one of the minimal Young’s moduli among the β-Ti family (about 55 GPa) and contains no cytotoxic elements. On the other hand, β-type Ti alloys are susceptible to bacterial infection because they lack an antibacterial function and can get contaminated quickly after implantation, making surface modification a keyway to improve these alloys' antibacterial properties. A recently created technique called powder mixed-EDM can improve machining, mechanical, and biological properties at the same time. In this research, silver was added to the dielectric fluid during PM-EDM of Ti-35Nb-7Zr-5Ta wt% alloy prepared by powder metallurgy route. The surface composition, Brinell hardness, corrosion resistance, ion release, and antibacterial properties were evaluated for TNZT alloy before and after surface modification. The results show better hardness and corrosion resistance as well as lower ion release for the PM-EDMed specimen due to the presence of Ag, oxides, and carbides such as NbC, TiC, TiO2, ZrO2, and Nb2O5 that’s deposited and embedded as a hard phase in the recast layer of the machined surface. Also, the antibacterial property of the PM-EDMed specimen is effectively improved as silver is an antibiotic with a wide range, so it has favorable antibacterial properties for Gram-negative and Gram-positive bacteria.

Keywords

• tnzt
• biocompatibility
• surface modification
• pm-edm
• silver
• antibacterial property