论文部分内容阅读
为阐明铬和钼对钢的局部腐蚀发展过程的影响,在类似于钢的闭塞腐蚀电池(OCC)内部溶液的条件下,研究了纯铬、纯铝和某些不锈钢的电化学行为。实验所用的溶液为无氧FeCl_2和/或CrCl_3。当pH高于约1.8时,Cr是钝化的,因此,在局部腐蚀发展的早期阶段,铬可起阻滞作用,但是,Cr~(3+)的水解可使pH降至更低值,在这种低pH和高Cl~-浓度条件下,在与钢的局部腐蚀对应的电位区,Cr是活化的。而在同样条件下,Mo是钝化的,而且在此电位区Mo的钝性归因于MoO_2膜的生成,这种氧化膜非常稳定,且保护性很好,因此,在局部腐蚀的深入发展阶段,Mo可有效地抑制腐蚀的发展。
To clarify the effect of chromium and molybdenum on the development of localized corrosion of steel, the electrochemical behavior of pure chromium, pure aluminum and some stainless steels was investigated in an internal solution similar to that of steel OCC. The solution used in the experiment is anaerobic FeCl 2 and / or CrCl 3. Cr is passivated when the pH is above about 1.8, so chromium can act as a retardation in the early stages of local corrosion development, however, hydrolysis of Cr ~ (3+) can lower the pH to a lower value, At this low pH and high Cl ~ - concentration, Cr is activated in the potential region corresponding to localized corrosion of the steel. Under the same conditions, Mo is passivated, and the passivation of Mo in the potential region is attributed to the formation of MoO 2 film. The oxide film is very stable and well-protected. Therefore, in-depth development of localized corrosion Phase, Mo can effectively inhibit the development of corrosion.