Electrochemical and Stress Corrosion Cracking Behavior of Alpha-Al Bronze in Sulfide-Polluted Salt Water: Effect of Environmentally-Friendly Additives

Elsayed A. Ashour, Lobna A. Khorshed, Gehan I. Youssef, Hossam M. Zakria, Tarek A. Khalifa

Electrochemistry Laboratory, Physical Chemistry Department, National Research Centre, Dokki, Cairo, Egypt.
Mechanical Engineering Department, Faculty of Engineering at Shoubra, Benha University, Cairo, Egypt.

DOI: 10.4236/msa.2014.51002                

Abstract

The stress corrosion cracking (SCC) behavior of α-Al bronze alloy (Cu₇Al) was investigated in 3.5% NaCl solution in the absence and in the presence of different concentrations of Na₂S under open circuit potentials using the constant slow strain rate technique. Also, the addition of different concentrations of cysteine (cys), and alanine (ala) to the test solution, as corrosion inhibitors, was studied. Increasing the sulfide ions concentration in polluted salt water resulted in a reduction in the maximum stress (σ_max) and an increase in the susceptibility of α-Al bronze towards SCC. The addition of ala and cys to the test electrolyte increased the time to failure by changing the mode of failure from brittle transgranular cracking to ductile failure. Electrochemical tests were performed to assist the interpretation of the SCC data. Electrochemical impedance spectroscopy (EIS) was used to investigate the mechanism of corrosion inhibition. The results support film rupture and anodic dissolution at slip steps as the operating mechanism of the SCC process. Therefore, cys and ala can be considered as potential environmentally-friendly corrosion inhibitors for the SCC of α-Al bronze in 3.5% NaCl solution containing sulfide ions.

Keywords

Bronze; Sulfide; Corrosion; SCC; Inhibitor; Amino Acids

Conflicts of Interest

The authors declare no conflicts of interest.

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