In vitro corrosion and mineralization of novel Ti–Si–C alloy

Abstract

The in vitro electrochemical behaviour of a new titanium based α-alloy (Ti–0.5 wt% Si–0.65 wt% C), fabricated via casting and rapid cooling route, was determined using linear, Tafel, potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS), complemented with ex situ SEM-EDS analysis to evaluate the corrosion mechanism. The experimental results revealed that silicon and carbon, in addition to titanium, resulted in the enhancement of mechanical properties. The polarization tests confirmed that Ti–Si–C alloy possessed excellent corrosion resistance (a low corrosion current density of 0.033 μA cm −2), comparable to cp Ti and better than Ti6Al4V in phosphate buffered saline (PBS). The mechanism of corrosion was identified as selective dissolution of titanium solid solution matrix. EIS studies indicated the formation of a stable, passive oxide film on the alloy. Further, in vitro bioactivity was evaluated using mineralization tests i.e. by immersing the pre-treated alloy in a concentrated simulated body fluid (10× SBF). Chemical and microstructural characterization of the mineral layer, formed during immersion, revealed the deposition of fine, porous micron-sized globules of a phase rich in calcium-phosphate (Ca-P). In summary, the bulk properties and excellent in vitro electrochemical and mineralization behaviour of the as-cast Ti–Si–C alloy reveal a high potential for its application as load bearing metallic implants.