10237 Crevice Corrosion Repassivation of Alloy 22 in Chloride Solutions

Available for download

Product Number: 51300-10237-SG

ISBN: 10237 2010 CP

Author: Martin A. Rodriguez, Mauricio Rincón Ortiz, Ricardo M. Carranza and Raul B. Rebak

Publication Date: 2010

Member Price: $0.00

Non Member Price: $20.00

Price: $20.00

Qty:

Alloy 22 (UNS N06022) belongs to the Ni-Cr-Mo family and it is highly resistant to general and localized corrosion, but it may suffer crevice corrosion in aggressive environmental conditions, such as high chloride concentration, high applied potential and high temperature. Alloy 22 is one of the candidates to be considered for the outer corrosion-resistant shell of high-level nuclear waste containers. It is assumed that localized corrosion will only occur when the corrosion potential (E_CORR) is equal or higher than the crevice corrosion repassivation potential (E_{R, CREV}). The latter is measured by means of different electrochemical techniques using artificially creviced specimens. These techniques include cyclic potentiodynamic polarization (CPP) curves, Tsujikawa-Hisamatsu electrochemical (THE) method or other nonstandardized methods. Recently, as a variation of THE method, the PD-GS-PD technique was introduced.

The aim of the present work was to determine reliable critical or protection potentials for crevice corrosion of Alloy 22 in pure chloride solutions at 90ºC. Conservative methodologies (which include extended potentiostatic steps) were applied for determining protection potentials below which crevice corrosion cannot initiate and propagate. Results from PD-GS-PD technique were compared with those from these methodologies in order to assess their reliability. Results from the CPP and the THE methods were also considered for comparison. The repassivation potentials from the PD-GS-PD technique were conservative and reproducible, and they did not depend on the amount of previous crevice corrosion propagation in the studied conditions.

Keywords: N06022, chloride, crevice corrosion, repassivation potential, CPP, ASTM G 61, THE, ASTM G 192