Corrosion behavior of C-276 alloy in supercritical water at 650 degree C/25 MPa

The corrosion behavior of nickel-base alloy Hastelloy C-276 was investigated in supercritical water (SCW) at 650 degree C/25 MPa. SEM, EDS, GIXRD and XPS were used to analyze the corrosion morphology, structure and element distribution of oxide film. The results show that the corrosion process of C-276 alloy at 650 degree C/25 MPa in SCW is mainly dissolution of Ni. Since it can not form a uniform and complete oxide film, the alloy in SCW is not well placed to corrosion resistance. The dual-layer oxide film structure which is formed on C-276 is rich in Cr but poor in Ni, Mo. The outer layer consisting of loose and large grains Ni(OH)2 and NiO agrees with dissolution and precipitation mechanism, while the growth of the Cr2O3 inner layer is the result of water through the porous oxides. (authors)