Enhanced self-lubricating and antibacterial activity by building hard-yet-tough Ta-Ag-N films on Ti-6Al-4V

The poor self-lubricating behavior and antibacterial activity of Ti-6Al-4V alloy hinder its medical applications in surgical instruments. And thus, Ag-based transition metal nitrides nanocomposite films on Ti-6Al-4V substrate where Ag existed in the form of nanoparticles have been commonly employed to improve the above properties. In this work, two kinds of Ag-based TaN films (similar to 3 at.% Ag) with solute Ag atoms and Ag nanoparticles are respectively fabricated on the surface of Ti-6Al-4V alloy by magnetron sputtering, aiming to insight into their self-lubricating behavior and antibacterial activity. It is revealed that as Ag resides in form of solute atoms rather than nanoparticles in Ta-Ag-N films, the enhanced antibacterial activity, lower coefficient of friction (CoF) coupled with raised hardness (similar to 39 GPa) and enhanced toughness can be achieved. Compared with the Ag nanoparticles, solute Ag atoms are considerably easier to form Ag2O in the atmosphere and to produce self-lubricating silver tantalate (AgTaO3) phase during the sliding, respectively contributed to the enhanced antibacterial activity and the drop in CoF. It suggests that the new strategy of incorporating solute Ag atoms into TaN can improve its self-lubricating ability and antibacterial activity for possibly extending the surgical instruments service life and reducing healthcare costs.