2001 Volume 50 Issue 7 Pages 323-329
We investigated the relation between the noise form and the corrosion form by means of the potential noise measurement for the crevice corrosion, SCC and SCC in crevice of type 304 SS in 3.5% NaCl solution at 80°C. The generation mechanism of potential noise is discussed through the scratch test, where corrosion current and potential were measured simultaneously at various corrosion potential, paying attention to the noise direction which changed depending on the corrosion potential. The potential noise took place in the less noble direction at the higher corrosion potential and at the higher pH, while it took place in the noble direction at the lower corrosion potential. It was found that the form of potential noise depends on the corrosion potential and pH, instead of corrosion form. Experimental results indicated that this dependency was resulted from the increased current on the bare surface, which current could be anodic or cathodic depending on the corrosion potential and pH of test solution.