Corrosion behaviour of porous Ti intended for biomedical applications

Porous Ti implants are being developed in order to reduce the biomechanical mismatch between the implant and the bone, as well as increasing the osseointegration by improving the bone in-growth. Most of the focus in the literature has been on the structural, biological and mechanical characterization of porous Ti whereas there is limited information on the electrochemical characterization. Therefore, the present work aims to study the corrosion behaviour of porous Ti having 30 and 50 % of nominal porosity, produced by powder metallurgy route using the space holder technique. The percentage, size and distribution of the pores were determined by image analysis. Electrochemical tests consisting of potentiodynamic polarization and electrochemical impedance spectroscopy were performed in 9 g/L NaCl solution at body temperature. Electrochemical studies revealed that samples presented a less stable oxide film at increased porosity, more specifically, the complex geometry and the interconnectivity of the pores resulted in formation of less protective oxide film in the pores.