Analysis of Dezincification Corrosion Behavior of Cu-30 mass%Zn Alloy by Electrochemical Impedance Spectroscopy

An electrochemical impedance spectroscopy was applied to the analysis of dezincification corrosion behavior of Cu-30 mass%Zn alloy. The impedance characteristics of Cu-30 mass%Zn alloy were different from those of Cu-30 mass%Zn alloy after dezincification corrosion susceptibility test (DCST). The impedance spectrum of Cu-30 mass%Zn alloy after DCST at arbitrary time showed the transmission line model type impedance in the high frequency range, indicating the current distribution on the copper rich layer formed on the alloy surface due to the selective dissolution of Zn. The maximum erosion depth of each sample after DCST was estimated from the cross-sectional images, demonstrating that these values were correlated to the low frequency impedance. These results imply that the selective dissolution rate of Zn from Cu-30 mass%Zn alloy can be evaluated by impedance measurement of Cu-30 mass%Zn alloy after DCST.