[Effect of pH value and fluoride ions on corrosion resistance of pure Ti and Ni-Cr-Ti alloy in artificial saliva].

To investigate the effect of pH value and fluoride ions on the corrosion resistance of pure Ti and Ni-Cr-Ti alloy in the artificial saliva.Electrochemical technique was used to measure the electric potential of corrosion (Ecorr), current density of corrosion (Icorr) and polarization resistance (Rp) of pure titanium and Ti-Ni-Cr alloy in the artificial saliva with different pH value and fluoride concentrations. After electrochemical analysis, microstructure and phase diffraction were examined by FSEM.With the lower pH value, the Ecorr and Icorr of pure titanium and Ti-Ni-Cr alloy increased, the Rp decreased, there was a significant difference (P<0.05). The Ecorr and Icorr increased markedly, the Rp significantly reduced in the artificial saliva containing 0.2% NaF (P<0.01). FSEM showed that pure titanium and Ti-Ni-Cr alloy surface corrosion, pure titanium in the artificial saliva containing 0.2% NaF was most serious.Lower pH value decreases the corrosion resistance of pure titanium and Ti-Ni-Cr alloy and the artificial saliva containing fluoride ions decreases the corrosion resistance of pure titanium.