Crevice Corrosion Penetration Rates of Alloy 22 in Chloride-Containing Waters

Effect of Oxide Film Properties on the Kinetics of O2Reduction on Alloy C-22

“…If these alloys are to suffer localized corrosion, the most likely form appears to be crevice corrosion, [14][15][16][17][18][19][20][21] and the accumulation of localized corrosion damage would require metal dissolution inside a creviced area to be supported by the cathodic reduction of O 2 on oxide-covered surfaces outside the crevice, although internal support by proton reduction has also recently been observed. 21 This makes knowledge of the kinetics for O 2 reduction essential for the development of corrosion models.…”

The crevice corrosion of Alloy 22 in the Yucca Mountain nuclear waste repository

“…On the other hand, neither stifling nor arrest was observed when PTFE creviced Alloy 22 was coupled to platinum and immersed for periods of 1 day to 51 days in 4 M MgCl 2 solution at 110°C, 84 which is contrary to that observed in 5 M NaCl at 95°C when PTFE creviced Alloy 22 was coupled to an Alloy 22 plate. 82,83 In the same work 84 the authors informed that in crevice corrosion tests using Alloy 22 or Ti G7 as metallic crevice formers in 4 M MgCl 2 at 95°C coupled either to Alloy 22 or to Ti G7, no stifling or repassivation was observed during the testing period (less than 40 days).…”

“…80,81 Stifling and repassivation in natural corrosion systems can arise from several causes, 82,83 including the inability to maintain a critical chemistry for stable crevice propagation due to anodic dissolution rate limitations brought about by a variety of causes such as the formation of a salt film or change in interface alloy composition due to incongruent dissolution, disruption in the geometric and physical conditions (e.g., corrosion product plugging) required to sustain the occluded site, evolution in alloy surface composition in the active crevice over time, and external cathode limitations and cathodic reaction starvation. 82,83 A. Yilmaz et al 42 studied the stifling process during potentiostatic tests, on PCA ASW Alloy 22 specimens immersed in pH 6 NaCl + KNO 3 solutions at 100°C. The crevice former used was a serrated PTFE tape covered ceramic with a torque of 7.9 N·m.…”

Corrosion of similar and dissimilar metal crevices in the engineered barrier system of a potential nuclear waste repository

“…In the current setup, positive current corresponds to anodic current from the crevice specimen. The galvanic coupling technique and the addition of CuCl 2 solution as an oxidant was previously used to measure the localized corrosion propagation rate of Alloy 22 [9,10].…”