Oxidation Characteristics of Haynes 282 Nickel-Based Alloy in Supercritical Water at 600-700℃

Haynes 282 nickel-based alloy was oxidized in supercritical water at 600-700℃ and 25 MPa, and then oxidation kinetics curves of the alloy and the surface morphology, microstructure and phase composition of the oxide film were investigated. The results show that the oxidation mass gain per unit area increased with the increase of the temperature and time. The oxidation kinetics curves followed parabolic law at 600℃ while obeyed the law between straight law and parabolic law at 650, 700℃. A double-layered oxide film was formed on the surface of the alloy. The outer layer consisted of scattered oxide particles in micrometer size with the loose polyhedral shape. The inner layer was a compact oxide film composed of tiny grains. The inner layer mainly composed of Cr₂O₃ and the outer layer composed of TiO₂ were formed on the surface of the alloy at 600℃. The outer layer of the oxide film at 650℃ was composed of MnCr₂O₄ and TiO₂, and the inner layer consisted of Cr₂O₃ and a small amount of MnCr₂O₄. The outer layer of the oxide film at 700℃ was composed of NiCr₂O₄ and MnCr₂O₄, and the inner layer consisted of Cr₂O₃ and a small amount of MnCr₂O₄.