CORROSION BEHAVIOR OF 70Cu-30Ni ALLOY IN 0. 5M NaCl AND IN SYNTHETIC SEAWATER.

Electrochemical corrosion rates of 70Cu-30Ni alloy have been measured in oxygenated 0. 5M NaCl and in synthetic seawater by the Tafel extrapolation procedure using a rotating disk electrode system. Corrosion rate measurements of freshly polished 70Cu-30Ni alloy in 0. 5M NaCl and in synthetic seawater indicated that the alloy corrodes differently in the two media and that the corrosion rate is much higher in 0. 5M NaCl than in SSW. In the former electrolyte, the alloy corrodes via the formation of a soluble corrosion product, and in the latter, via a passivation process. The corrosion current and corrosion potential in 0. 5M NaCl were dependent on the rotation rate of the electrode, as expected, while in SSW, both quantities were independent of rotation rates because a surface kinetic process rather than a diffusion process controls the corrosion mechanism.