Abstract:The corrosion behaviors of copper and copper/titanium galvanic couple (GC) in seawater were studied by electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) techniques in conjunction with scanning electron microscopy (SEM) method. The results show that the corrosion process of copper in seawater can be divided into two stages, in which corrosion resistance and S_E show the same evolution trend of initial increase and subsequent decrease, while S_G changes oppositely. However, the ensemble corrosion process of copper/ titanium GC in seawater includes three stages, in which corrosion resistance and S_E show the evolution features of initial decrease with a subsequently increase, and the final decrease again; while S_G changes oppositely. The potential difference between copper and titanium in their galvanic couple can accelerate the initiation of pitting corrosion of copper, and both the minimum and maximum corrosion potentials of copper/ titanium GC are much more positive than those of pure copper.

Key words: Cu/Ti galvanic couple; galvanic corrosion; electrochemical impedance spectroscopy; electrochemical noise