Open AccessGeneral Corrosion and Passive Film Stability
Author(s) -
C Orme,
J Gray,
J Hayes,
L Wong,
R Rebak,
S Carroll,
J Harper,
G Gdowski
Publication year - 2005
Language(s) - English
Resource type - Reports
DOI - 10.2172/923096
Subject(s) - corrosion , oxide , alloy , materials science , metal , evaporation , metallurgy , weight change , electrochemistry , crevice corrosion , weight loss , chemistry , meteorology , medicine , physics , electrode , obesity
This report summarizes both general corrosion of Alloy 22 from 60 to 220 C and the stability of the passive (oxide) film from 60 to 90 C over a range of solution compositions that are relevant to the in-drift chemical environment at the waste package surface. The general corrosion rates were determined by weight-loss measurements in a range of complex solution compositions representing the products of both the evaporation of seepage water and also the deliquescence of dust previously deposited on the waste canisters. These data represent the first weight-loss measurements performed by the program at temperatures above 90 C. The low corrosion rates of Alloy 22 are attributed to the protective oxide film that forms at the metal surface. In this report, changes in the oxide film composition are correlated with weight loss at the higher temperatures (140-220 C) where film characterization had not been previously performed. The stability of the oxide film was further analyzed by conducting a series of electrochemical tests in progressively more acidic solutions to measure the general corrosion rates in solutions that mimic crevice or pit environments