Titanium alloys are candidate materials for the fabrication of high level nuclear waste containers but may be susceptible to crevice corrosion in the initial warm oxidizing conditions anticipated in a deep geological repository. The crevice corrosion of Grade-2 titanium has been studied in 1.0 mol/L NaCl at various temperatures (120 degrees C and 150 degrees C) and oxygen concentrations using a galvanic coupling technique. The current due to propagation supported by oxygen reduction on the surface external to the crevice was monitored electrochemically and the total propagation determined from weight change measurements. The redistribution of impurities (Fe, V, Mo) during corrosion was determined by dynamic secondary ion mass spectrometry. Propagation was dominantly driven by the reduction of protons created inside the crevice by cation hydrolysis. Damage accumulated at the locations of TixFe intermetallic particles, which are both anodically reactive and function as catalytic cathodes for proton reduction. The compact TiO2 center dot xH(2)O deposits at active sites led to stifling of corrosion when only between 9 and 56% of the available oxygen had been consumed. While propagation was more rapid at 150 degrees C than at 120 degrees C, it was more readily stifled at the higher temperature, leading to the accumulation of less damage. (c) The Author(s) 2017. Published by ECS. All rights reserved.
Standish, T. E., Yari, M., Shoesmith, D. W., & Noël, J. J. (2017). Crevice Corrosion of Grade-2 Titanium in Saline Solutions at Different Temperatures and Oxygen Concentrations. Journal of The Electrochemical Society, 164(13), C788–C795. https://doi.org/10.1149/2.0941713jes