Binary nickel-chromium alloys (0 -45 mass-% Cr) were exposed to an aqueous solution which resulted from the oxidation of dichloromethane in the presence of hydrogen peroxide at 400 bar and temperatures between ~100° and 415°C; the composition of the reaction medium after complete oxidation of the chlorinated hydrocarbon and decomposition of hydrogen peroxide was 0.12 mol/kg-H2O hydrogen chloride, 0.06 mol/kg-H2O oxygen and 0.06 mol/kg-H2O carbon dioxide. Under these conditions, minimum corrosion of binary nickel-chromium alloys was found to occur for chromium contents in the range of 25 mass-% or, more precisely – when results of other investigations are included – between 10 and 25 mass-%. Aspects of the corrosion mechanisms and kinetics were derived from comparison with the predictions of a mathematical model. Some recommendations, how the operation conditions for the SCWO process can be optimized in regard to minimal chemical degradation of nickel-chromium-based reactor materials, are given.

Subject
Materials, Corrosion kinetics, Corrosion rate, Reactors, Nickel based alloys, Chromium, Corrosion reactions, Density, Corrosion products, Supercritical water oxidation, Chemical reactions, Hydrogen, Types of corrosion
Keywords:
supercritical water, oxidation, SCWO, dichloromethane, hydrogen chloride, corrosion, high temperature, high pressure, nickel, chromium
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2004
Association for Materials Protection and Performance (AMPP)
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