Characterization of laser surface-alloyed Ti-Ni-Ag coatings and evaluation of their corrosion and antibacterial performance

The novel antibacterial Ti-Ni-Ag coatings with various Ag contents (2.1 to 4.6 wt%) were successfully fabricated on TiNi substrate using laser surface alloying. Microstructure, hardness, corrosion and antibacterial properties of the laser surface-alloyed (LSAed) Ti-Ni-Ag coatings were investigated. In the alloyed layers, more Ti2Ni, beta-Ti, and Ag particles are formed with a higher Ag content. The hardness of coating with 4.6 wt% Ag is increased by 109 % as compared with the TiNi substrate mainly attributed to the high Ti2Ni content. Compared with TiNi, the corrosion resistance of LSAed Ti-Ni-Ag coatings was enhanced as evidenced by a noble shift in the corrosion potential and a lower passive current density owing to the thicker and denser passive films, which was further confirmed by scanning electrochemical microscopy (SECM), X-ray photoelectron (XPS) and Mott-Schottky an-alyses. Also, it was found that the released Ag+ ions and Ag particles are responsible for enhancing the anti-bacterial efficacy of the LSAed Ti-Ni-Ag against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).