Abstract
Titanium alloys are frequently chosen for many internal autoclave parts subjected to extremely corrosive environments, such as those prevalent in hydrometallurgical pressure leaching. We present the kinetics of the ferric/ferrous couple on Ti-G5 (Ti-6Al-4V) and the resulting corrosion behaviour of this alloy in H2SO4-H2O from 25–150°C. The presence of Fe2+ and Fe3+ enhanced the anodic passivity of Ti-G5 in sulfuric acid, with a small addition of Fe3+ increasing the polarization resistance the most. The results clearly show that when the Fe3+ to Fe2+ ratio is increased, the passive film is more stable.