Effect of SO 2 and pH on the Anodic Behavior and Pitting Corrosion of Alloy 600
Effect of SO 2 and pH on the Anodic Behavior and Pitting Corrosion of Alloy 600
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DOI：
10.1149/1.2123474
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发表时间：
1982-10
影响因子：
3.9
通讯作者：
P. Berge;V. Jovancicevic;D. Noel;P. Saint-Paul
中科院分区：
文献类型：
--
作者：
P. Berge;V. Jovancicevic;D. Noel;P. Saint-Paul
The anodic behavior and pitting corrosion of Alloy 600 in solutions containing low concentrations of SO~ and H~ SO~ were studied by cyclic voltammetry near the activation peak. The results are presented in the form of an [H2SO4] vs.[SOztot] corrosion diagz'am for different sweep rates. A model based on the competitive adsorption of SO2 and HSO3 is proposed. The effect ofpH on the various adsorption states is discussed. The adsorption of HSO3-anions gives rise to the breakdown of the oxide film and that of SO2 provides a protective effect; the adsorption of SO2 depends very strongly on the pH. Two types of pitting were observed at different potentials in the activation range. Relatively few and deep pits occur at low HSO~-concentrations (-0.47 V/SSE) while numerous and shallow pits develop at higher concentrations (-0.52 V/SSE).Recently, pitting corrosion observed during storage of AHoy 600 tubes for steam generators of pressurized water reactors was attributed to the presence of oxidized sulfur species (SO2, SO42-, HSOa-,...) and humidity. The role of SO2 on atmospheric corrosion was recognized very early (1) and studied by several authors (2-5). Low alloyed steels rust in these atmospheres and the corrosion products contain mainly sulfates. On the other hand, stainless steels exposed for long times to industrial atmospheres can undergo pitting corrosion (6). The effect of SO2 on anodic behavior of Fe-Cr-Ni alloys was studied in sulfuric acid solutions and the increasing of the rate of active dissolu-
