Corrosion behavior of Alloy 690 in aerated supercritical water

The oxidation behavior of Alloy 690 exposed to aerated supercritical water at different temperatures was investigated using gravimetry, scanning electron microscopy/energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and electron probe micro-analyzer. The oxide films showed a duplex layer structure with Ni and Fe rich in the outer layer, and Cr rich in the inner layer. Some pits and nodules observed in the oxide films could be related to TiN inclusions in the alloy matrix. The oxidation mechanism and effects of TiN inclusions are discussed. (C) 2012 Elsevier Ltd. All rights reserved.