The influence of passivation type on corrosion resistance of Ti15Mo alloy in simulated body fluids

Abstract

This work reports on determination of the influence of passivation type of Ti15wt.%Mo implant alloy surface on its corrosion resistance in simulated body fluids. The alloy under investigation was subjected to natural self-passivation in air, and forced passivation by autoclaving in steam, boiling in 30 % solution of H2O2, and electrochemical passivation in 0.9 % NaCl solution. Resistance of the passivated Ti15Mo alloy to pitting corrosion was studied at 37°C in 0.9 % NaCl solution using open circuit potential method, anodic polarization curves, and electrochemical impedance spectroscopy (EIS). Comparative estimation of the determined parameters of corrosion resistance revealed that the obtained passive layers improve anticorrosive properties of the tested alloy. Surface of the alloy subjected to passivation in steam autoclave reveals the highest protection against pitting corrosion. Anodic potentiodynamic curves showed that the Ti15Mo alloy after different passivation types of the surface is characterized by a lack of susceptibility to pitting corrosion up to potential of 9 V. Based on the EIS investigations, the thickness of the formed oxide layers (TiO2, anatase) was determined to be in the range from 2.0 to 7.8 nm in dependence on the applied type of passivation. It was ascertained that electrochemical properties of the Ti15Mo alloy and possibility of its surface passivation using simple methods, make it an attractive material for use in biomedicine for long-term implants.