Effect of Cr on the reduction behavior of corrosion product formed on low alloy steels in flowing thin electrolyte layer

摘要

The reduction behav ior of rust layer formed on carbon steel and on Cr - containing steels has been investigated in flowing thin electrolyte layer with 3.5% NaCl solution, via potentiodynamic polarization curve, EPMA, Raman spectroscopy, XRD, and XPS. The cathodic potentiodynam ic polarization curves of carbon steel and Cr - containing steels were carried out in flowing thin electrolyte layer with vacuum environment, for eliminating the reduction reaction of oxygen. Results show that the cathodic reaction of Cr -containing steels wa s inhibited by concentration of Cr in the inner rust layer, and the reduction of rust layer formed on Cr-containing steels was also inhibited. The constituent of rust layer formed on carbon steel was the same with that of Cr -containing steels. However, the amount of Fe 3O4 in the rust layer formed on carbon steel was higher than those formed on Cr -containing steels after cathodic potentiodynamic parization curves. It indicates that the reduction of Fe 3+ was suppressed for Cr -containing steels. Cr exited in the form of Cr 3+ in the corrosion product, participating in the transformation of corrosion product.