Aspects of the Corrosion Kinetics for Binary Nickel-Chromium Alloys Under Conditions Found in Supercritical Water Oxidation Plants Processing Chlorinated Substances Available to Purchase

Binary Ni-Cr alloys (0 to 45 mass% Cr) were exposed to an aqueous solution resulting from the oxidation of dichloromethane (CH₂Cl₂) in the presence of hydrogen peroxide (H₂O₂) at 40 MPa and temperatures between ~100°C and 415°C. The composition of the reaction medium after complete oxidation of the chlorinated hydrocarbon was 0.12 m hydrochloric acid (HCl), 0.06 m oxygen (O₂), and 0.06 m carbon dioxide (CO₂). Of the alloys investigated, NiCr25 performed best in experiments for 120 h under these conditions. Aspects of the complex corrosion kinetics for binary Ni-Cr alloys are compared with the predictions of a mathematical model. Results from other investigations that cover temperatures up to 500°C at a comparable pressure are reviewed in light of the new findings.