Effect of temperature on copper corrosion in high-level nuclear waste environment
(Corrosion and Protection Center, Key Laboratory for Corrosion and Protection, Ministry of Education, University of Science and Technology Beijing, Beijing 100083, China)
Abstract: The effect of temperature on the corrosion behavior of copper in simulated high-level nuclear waste environment was systematically studied. Electrochemical methods, including electrochemical impendence spectra, Mott–Schottky technology, cyclic polarization, and potentiostatic polarization, were employed to characterize the corrosion behavior of copper at different temperatures. Stereoscopic microscopy and scanning electron microscopy were used to examine the surface morphology, and X-ray photoelectron spectroscopy analysis was used to identify the composition of the passive film. The experimental results show that corrosion resistance of the passive film does not blindly decrease with the increase of temperature but increases at 60 °C owing to a compact outer layer; there is a potential for pitting corrosion, which decreases as the temperature increases. The main product of copper in an anaerobic aqueous sulfide solution is Cu2S but the content of CuS increases at higher temperatures. The whole passivation range shows p-type semiconductor characteristics and the magnitude of the acceptor density is 1023 cm-3, which increases with increasing temperature.
Key words: copper corrosion; sulfide; nuclear waste disposal; temperature; electrochemical performance