Corrosion performance of the biocompatible -Ti12Mo6Zr2Fe alloy submitted to laser and plasma-nitriding surface modifications

The corrosion behaviour of laser and plasma nitrided beta-Ti12Mo6Zr2Fe biomaterial was evaluated. Polarisation curves and electrochemical impedance spectroscopy were performed in simulated body fluid (SBF) at 37 degrees C. Both treatments formed titanium-nitride at the alloy's surface, and significantly improved the corrosion performance of the alloy. At anodic potentials of the order of 1.0 V, the titanium-nitride layer seems to oxidise, independent of the nitriding process. Nanometric fissures formed on the plasma titanium-nitride layer seems to govern the impedance response at low frequencies, exposing the substrate to the electrolyte. Laser titanium-nitride layer is thicker and lead to a better corrosion performance.