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 5/37degreesC) 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 (E-corr), corrosion rate (I-corr), passive current density (I-pass), and polarization resistance (R-p) (p<0.01). The I-corr and I-pass 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. (C) 2002 Elsevier Science Ltd. All rights reserved.