Effect of temperature on corrosion behavior of alloy 690 in high temperature hydrogenated water

摘要

The influence of temperature on the corrosion behavior of Alloy 690 is evaluated using potentiodynamic polarization curves,electrochemical impedance spectra(EIS),scanning electron microscopy(SEM),Xray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM).The corrosion rate of Alloy 690 reaches a local maximum at 250?C.The kinetic control step of the growth of oxide film changes from the diffusion process of aqueous-phase ions to the growth of Cr-rich barrier layer in the temperature range of 200–300?C.A modified double-layer model is proposed to describe the effect of temperature on the structure and composition of the oxide film.