Effect Of Seawater Chlorination On The Erosion Corrosion Behavior Of Copper-Nickel Alloy Cuni90/10

The influence of dissolved sodium hypochlorite on the flow resistance of UNS C70600 (CuNi90/10) in artificial ASTM D1141seawater at room temperature was investigated gravimetrically using the rotating cage and the electrochemically controlled submersed jet impingement tests. It appeared that even under unfavorable conditions (as-delivered surface, 5 ppm hypochlorite) the critical wall shear stress for initiation of flow induced localized corrosion (FILC) reached levels of 200 Pa. Six weeks pre-exposure in hypochlorite-free artificial seawater at room temperature yields flow resistant protective scales which resist wall shear stresses up to 370 Pa (even in the presence of 5 ppm hypochlorite) without initiation of FILC. The value of 43 Pa previously reported in the literature for the critical wall shear stress of CuNi90/10 in seawater is obviously much too conservative.