Effect of Sulfide on the Corrosion of Cu‐9.4Ni‐1.7Fe Alloy in Aqueous NaCl Solution

Publisher Website
Google Scholar
Abstract
The effects of sulfide contamination (5 ppm) on the corrosion mechanism of Cu‐9.4Ni‐1.7Fe alloy were studied in solution at room temperature. Compared to the sulfide‐free solutions (i), the thickness of the corrosion products formed in the sulfide solution is much greater, and (ii) the anodic polarization curves measured in clean solution after immersion in the solution containing sulfide are somewhat less polarized but are otherwise similar, whereas (iii) the cathodic polarization curves are very much less polarized (100 times). This much increased cathodic rate is mainly responsible for the increased corrosion rate caused by prior exposure to a solution containing sulfide. After stripping the loosely adherent corrosion products containing sulfide, the corrosion rate fell to a negligible level comparable to that obtained for sulfide‐free corroded samples. These results show that sulfide increases the corrosion rate through its effect on the outer corrosion products, rather than on the thin inner layer next to the metal. Since the outer corrosion products are porous, it follows that sulfide's dominant role is that of a catalyst for the oxygen reduction reaction. This explanation is consistent with other results for sulfide‐free corroded samples.

This publication has 0 references indexed in Scilit: