Anodic Polarization Behavior of Titanium and Titanium Alloys in Sulfuric Acid Solutions

摘要

The study was made to investigate the anodic polarization behavior of commercially-available titanium alloys in sulfuric acid solutions. Six materials were investigated at 22 plus or minus 1C using the potentiostatic technique. The electrolyte was 1, 5, and 10 normal concentrations of hydrogen-saturated, sulfuric acid. Anodic polarization curves (potential versus log current density) were obtained for all specimens in each of the three acid solutions. In addition, corrosion potential runs were determined for a 0.1N H2SO4 solution. All specimens display an active-to-passive transition. The alloy containing 13V-11Cr-3A1 was the only specimen investigated which exhibited transpassive behavior in the normal range of interest (E sub corr to +3.0 volts). None of the specimens exhibited Tafel behavior for anodic dissolution in the active region or in the transpassive region. The passive current density, ip, was less than 20 microamps/sq cm for all specimens, indicating the presence of a stable passive film on the specimen surface. The magnitude of the passive current density, ip, did not vary significantly with acid concentration. The passivation potential, Ep, became more noble (positive) with increasing acid concentration. The magnitude of the critical current density, icr, increased with increasing acid concentration. The corrosion potential was essentially constant for the 1, 5, and 10 normal environments. It was more noble by 0.2 to 0.4 volts in 0.1N acid concentrations for all specimens except the Ti-8A1-1Mo-1V alloy, for which it is more noble by almost 0.7 volts. (Author)