 |
Wednesday, March 19, 2008 - 9:35 AM
Convention Center, Second Level, 210 (Ernest N. Morial Convention Center)
08579
Anodic and Cathodic Behavior of Mill Annealed and Topologically Closed Packed Alloy 22, in Chloride Solutions
Alloy 22 (N06022) belongs to the Ni-Cr-Mo family and it is highly resistant to localized corrosion. Anodic and cathodic behavior of mill annealed (MA) and thermally aged (10 hours at 760ºC) samples (TCP) of Alloy 22 was studied in chloride solutions of different pH values at 90ºC . Thermal aging leads to a microstructure of full grain boundary precipitation of topologically closed packed phases. Electrochemical tests included monitoring of open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. Assessment of general and localized (crevice) corrosion was performed as well as determination of Tafel slopes in the studied environments. Repassivation potentials were obtained from cyclic potentiodynamic polarization tests. Results indicated that MA and TCP samples show similar general corrosion rates and crevice corrosion resistance in the tested environments. MA and TCP samples suffered general corrosion in an active state when tested in low pH chloride solutions. In this case the grain structure of the alloy was revealed for MA samples, while TCP samples suffered a preferential attack at grain boundaries. The passive film behaved as an n-type semiconductor in the passivity potential range, showing the same 1/C2 vs. E response for MA and TCP samples.
See more of Corrosion in Nuclear Systems - Session 1
See more of Technical Symposium
See more of The CORROSION 2008 Conference and Expo (March 16-20, 2008)
See more of Technical Symposium
See more of The CORROSION 2008 Conference and Expo (March 16-20, 2008)