Duplicate galvanic couples with aII area ratio were constructed from all combinations of the following materials: type 304L stainless steel, 90/10 copper-nickel, 70/30 copper-nickel, nickel-aluminum bronze, silicon bronze, and copper. In addition, duplicate panels of each of these materials were catholically protected with either anode grade zinc or iron. Exposures were conducted in natural seawater flowing at 5-ft/s for 375 days while monitoring galvanic current and couple potential. Major changes in galvanic currents tended to occur within the first 120-days exposure, although drift to lower currents was observed over the entire test period. Couple potentials were highly variable over the entire exposure period. but major potential drift tended to occur within the first 120 days. The highest current densities for couples not including zinc or iron were for all of the 304L couples, particularly those with silicon bronze and copper, nickel-aluminum bronze coupled to silicon bronze or copper, and 70/30 copper-nickel coupled to silicon bronze or copper. Current densities for all other couples were below I mA/ft2 and should result in low total currents for reasonable anode/cathode area ratios.
Keywords: galvanic corrosion, cathodic protection, current density, polarization, seawater, stainless steel, coppernickel, nickel-aluminum bronze, silicon bronze. copper, iron, zinc