Effect of Buffering on Electrochemical Corrosion Behavior of Alloy 800 in Sulfate Solutions Containing Hydrogen Peroxide

摘要

Corrosion behavior of Alloy 800 (UNS N08800) in the presence of hydrogen peroxide is important because of its potential application in the future power plants. The aim of this study is to evaluate how local variation of pH alters both the electrochemical reduction of hydrogen peroxide and electrochemical corrosion behavior of Alloy 800 in sulfate solutions. Cathodic polarization test was used to evaluate the kinetics of reduction of hydrogen peroxide. Linear polarization resistance, electrochemical impedance spectroscopy and potentiodynamic polarization tests were used to study the corrosion behavior in presence and absence of buffering agent. The results show that the reduction of hydrogen peroxide in the presence of KH_2PO_4 as the buffering agent show two cathodic waves while only one cathodic wave is observed in the unbuffered solutions. The polarization resistance obtained by linear polarization resistance method was decreased from 50 kΩ cm~2 to 7 kΩ cm~2 by introduction of the buffering agent. These results were consistent with the impedance spectra trend.