Corrosion of Ti biomaterials

Abstract

The experimental investigation of corrosion stability of Ti-35.4Zr-28Nb in synthetic body fluid was conducted to aid in the development of a porous Ti alloy for use as a bone replacement material. The corrosion analysis was conducted using immersion testing for 28 days, Open Circuit Potential (OCP), Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarisation curves. The corrosion performance of the Ti alloy was compared to that of commercial purity (CP Ti) Grade 2 under in-vitro testing conditions in:1. Hanks' solution at 37 °C 2. 3.5% NaCl solution at 95 °C Immersion testing results of both the materials showed negligible weight loss and low concentration of Ti, Zr and Nb, which indicates a low corrosion rate. In addition, the electrochemical testing indicated passivation behaviour which was further supported by the partial stabilisation of current density and overall low current densities (in the order of 10 -6 A/cm 2 ). The OCP measurement also described a passivation behaviour with an increase in the corrosion potential and a stabilised curve over time.Overall, from the experimental results, no significant evidence of crevice corrosion was observed under the testing conditions indicating that both CP Ti and the Ti alloy are not sensitive to crevice corrosion.iii