Effect of fluoride and albumin concentration on the corrosion behavior of Ti–6Al–4V alloy

The purpose of this study was to investigate the effect of fluoride and albumin concentration on the corrosion behavior of Ti–6Al–4V alloy in acid artificial saliva (pH 5/37°C) using potentiodynamic polarization and linear polarization test. Chemical analyses of the surface passive film were characterized using X-ray photoelectron spectroscopy. The results showed that either the NaF (0–0.5%) or the presence of albumin (0–0.2%) in 0.1% NaF-containing media had a significant influence on the corrosion potential (Ecorr), corrosion rate (Icorr), passive current density (Ipass), and polarization resistance (Rp) (p<0.01). The Icorr and Ipass values increased on increasing the NaF concentration, but decreased with the presence of albumin in NaF-containing media. The Rp value decreased on increasing the NaF concentration, but increased with the presence of albumin in NaF-containing media. When the NaF concentration was higher than 0.1%, the protectiveness of TiO2 passive film formed on Ti–6Al–4V alloy was destroyed by fluoride ions, leading to the formation of Na2TiF6. The presence of albumin, regardless of the concentration, in 0.1% NaF-containing acid media improved the corrosion resistance of Ti–6Al–4V alloy.