10197 Oxidation of Stainless Steels and Nickel-Base Alloys in Supercritical Water Containing H2O2 Environments

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Product Number: 51300-10197-SG

ISBN: 10197 2010 CP

Author: Xinqiang Wu, Mingcheng Sun, En-Hou Han

Publication Date: 2010

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Corrosion behaviors of stainless steels and nickel-base alloys were investigated in H₂O₂-containing SCW environments. The effects of temperature, exposure time and H₂O₂ concentration were examined. The mass gain and the morphologies, microstructures, compositions and structures of the oxide scales were investigated using weight measurement, X-ray photoelectron spectroscopy, grazing incidence X-ray diffractometry, scanning electron microscopy and transmission electron microscopy. Duplex layers of the oxide scales were observed for both the stainless steel and nickel-base alloy after exposure in SCWO environments, consisting of an outer layer of large-grain oxides and an inner layer of fine-grain oxides. The duplex-layer structure was identified to be Ni(OH)₂/NiO/NiCr₂O₄/Cr₂O₃/alloy matrix from outer to inner layer for the nickel-base alloy, and to be FeOOH/(Fe,Cr)₂O₃/ (Fe,Cr)₃O₄/Cr₂O₃/Ni-rich layer/steel matrix for the stainless steel. A nickel enrichment was observed at the oxide/matrix interface for the stainless steel, especially at higher temperatures. The growth mechanisms of the oxide scales on the stainless steel and nickel-base alloy are discussed.

Keywords: Supercritical water oxidation, stainless steels, nickel-base alloys, oxide scales