Studies of Corrosion and Electrochemical Behavior of Cu-Zn Alloys in H_2SO_4 and HNO_3 Acid Solutions

Walaa A. Hussein ； Amal S. I. Ahmed ； Wafaa A. Ghanem ； Ghalia A. Gaber

《Journal of Metallurgical Engineering》 5卷 (2016/03) Pp. 27-37

https://doi.org/10.14355/me.2016.05.003

摘要

The electrochemical corrosion behavior of Cu-Zn alloys in different concentrations of H_2SO_4 and HNO_3 acid solutions was studied using open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Open-circuit measurements showed that both immersion potential (E_(im.)) and steady state potential (E_(s.s.)) for the Cu-Zn alloys decreased and shifted to more negative values as the concentration of H_2SO_4 and HNO_3 increased. The increase in acid concentration accompanied with increase in the corrosion current density, I_(corr), corrosion rate, C.R. Also, it is observed that the anodic Tafel slope values are almost increased as the concentration of acid increased. The impedance response consisted of characteristic depressed semicircles which clarifying that the corrosion process occurs under charge transfer control. The presence of 2.43 % aluminum in the Alloy II improves the corrosion resistance in H_2SO_4 and HNO_3 media as compared to Alloy I. The charge transfer resistance values, R_(ct), for the Cu-Zn alloys (I and II) in H_2SO_4 and HNO_3 acid solutions follow the order: Alloy II ＞ Alloy I. The results obtained from both methods were in good agreement. These results have also been confirmed through the SEM and EDX.

關鍵字

Corrosion ； Cu-Zn Alloys;Oxy-acid Solution ； Electrochemical Techniques;Spectroscopic Analysis