AVS 60th International Symposium and Exhibition
    Applied Surface Science Wednesday Sessions
       Session AS-WeA

Paper AS-WeA10
Quantitative Characterization of Corrosion Oxides on Metal Alloy Surfaces Exposed to High Temperature Water

Wednesday, October 30, 2013, 5:00 pm, Room 204

Session: Developments in Electron Spectroscopies for Non-Ideal Samples 2
Presenter: M.C. Burrell, Bechtel Marine Propulsion Corporation
Authors: M.C. Burrell, Bechtel Marine Propulsion Corporation
J.T. Orr, Bechtel Marine Propulsion Corporation
T.K. Nolan, Bechtel Marine Propulsion Corporation
M.J. LeClair, Bechtel Marine Propulsion Corporation
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Corrosion of metal alloys in high temperature (~500 oF) water results in the formation of a retained oxide film and the preferential release of metal ions into solution. Quantification of the composition and mass of the retained oxide is required to determine the amount of base alloy consumed, and the identity and quantity of released metal ions. We have characterized the oxide formed on a series of steels, nickel-based alloys, and a cobalt-chromium alloy (Stellite-6B) using a combination of surface analysis, microscopy, and gravimetric methods. These oxide films range from a few tens of angstroms up to several microns in thickness. Electron Spectroscopy for Chemical Analysis (ESCA) depth profiling provides a measure of the relative proportion of metal ions in the oxide film and changes in near-surface composition of the metal; oxide film mass is ideally determined gravimetrically using a chemical dissolution method. In the case of the thin, resistant oxide formed on Stellite, the gravimetric approach was not satisfactory, and the oxide thickness was determined using electron microscopy. This presentation will describe the challenges encountered in the characterization of these complex surfaces, and some general trends in the corrosion behavior as related to alloy composition and surface finish.