Corrosion performance of high damping alloys in 3.5% sodium chloride solution

Abstract

The electrochemical nature of corrosion provides a means of determining an almost instantaneous corrosion rate. Corrosion rate and the nature of corrosion attack were investigated for several high damping alloys based on the Cu-Mn, Fe-Cr-Al, Fe-Cr- Mo, and Cu-Zn systems in 3.5% NaCl solution. The results of Potentiodynamic polarization and polarization resistance measurements were compared with the results of actual sea exposures. A zero resistance ammeter technique was used to measure the galvanic currents between galvanically coupled metals. The magnitude of the galvanic current provide an indication of the severity of galvanic corrosion which occurs in a 3.5% NaCl environment. Scanning electron microscopy (SEM) was used to determine the nature of corrosive attack and the extent of film formation on the surface of each corroding alloy. Results from Laboratory and actual sea exposures showed that the Fe-Cr-Al and Fr-Cr- Mo high damping alloys experienced severe localized corrosion and pitting. 630 Bronze and Cu-Mn-Al based alloys indicate low to moderate corrosion rates.