잔류 염소가 포함된 해수에서의 Cu-Ni 합금의 부식 거동 연구

Abstract

Corrosion of the Cu alloy with 10wt% Ni in stagnant seawater with residual free chlorine was investigated. Despite that fact that Cu alloys are widely used for seawater applications due to their stubborn resistanceto chloride attack, not much is known as to how the residual free chlorine in seawater affects corrosionof Cu and its alloys. In this work, immersion tests were conducted in the presence of different levelsof chlorine for 90-10 Cu-Ni samples, one of the most frequently used Cu alloys for seawater application,mostly in shipbuilding. The results revealed no evidence for accelerated corrosion of the Cu-Ni alloyeven in the presence of 5 ppm residual chlorine in seawater, signifying that the Cu-Ni alloy can bemore tolerant to residual chlorine that has been commonly cited by the shipbuilding industry. However,comparison of polarization behavior of the alloy samples in the presence of different electrolytes withdifferent concentrations of residual chlorine suggests that higher concentration of chlorine could increasethe corrosion rate of the Cu-Ni alloy. Furthermore, it is suggested that microorganisms in the seawatercould increase the corrosion rate of the Cu-Ni alloy by encouraging exfoliation of the corrosion productoff the metal surface.